The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
665
Influence of Periodontal Biotype on Root Surface Exposure During Orthodontic Treatment: A Preliminary Study Giulio Rasperini, DDS1 Raffaele Acunzo, DDS2 Paola Cannalire, DDS3 Giampietro Farronato, MD, DDS4
The aim of this study was to investigate the role of periodontal biotype in the development of gingival recession in patients who have undergone orthodontic treatment. A total of 60 mandibular incisors were analyzed. The qualitative assessment of periodontal biotype was performed with the use of a new biotype probe. A strong correlation was found between thin biotype and proinclination in terms of recession depth and keratinized tissue width. Patients with thin periodontal biotype are more prone to gingival margin instability, irrespective of the type of orthodontic movements. Thin periodontal biotype and proinclination orthodontic movement were related to loss of keratinized tissue width. (Int J Periodontics Restorative Dent 2015;35:665–675. doi: 10.11607/prd.2239)
Professor, Unit of Periodontology, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 2Research Fellow, Unit of Periodontology, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 3Graduate Resident, Unit of Periodontology, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 4Professor of Orthodontics, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 1
Correspondence to: Dr Raffaele Acunzo, Via Monte Grappa 12, 20126 Novate, Milan, Italy. Fax +39-02-3512986. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
According to the International Workshop for a Classification of Periodontal Diseases and Conditions, the gingival/soft tissue recessions on the vestibular or lingual surfaces or interproximal (papillary) areas are classified in the group of “development or acquired mucogingival deformities and conditions around teeth”1 and are defined as the displacement of the marginal tissue apical to the cementoenamel junction. The resulting root exposure is not esthetically pleasing and may lead to dentinal sensitivity and root caries. The occurrence of gingival recessions is age-dependent and their development begins relatively early in life.2 Gingival recessions were noticed in more than 60% of Norwegian 20-year-olds and in more than 90% of the older population (> 50 years);2 in populations deprived of dental care, the occurrence of root exposures was even higher.2 Although its etiology is unclear, periodontal disease and mechanical trauma are considered the primary factors in the pathogenesis of gingival recession defects. Traumatic tooth brushing,3 intra- and perioral piercings,4 bruxism,5 and microbiologically induced inflammation in periodontal connective tissue6 have been proposed as the most important factors. Consanguinity between orthodontic
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
666 Fig 1 Periodontal biotype probes from different views.
a
b
c
Figs 1a and 1b A qualitative assessment of the gingival thickness can be performed to evaluate the visibility of the colored tip of the probe through the gingival tissue.
Thin
tooth movement and gingival recession has also been a common anecdotal observation in the periodontic and orthodontic literature.7 However, experimental evidence suggests that orthodontic tooth movement does not actually cause gingival recession but might create an environment that predisposes some people to the condition. Orthodontic tooth movement can result in root positions near or outside the labial or lingual alveolar bone plate; this can lead to bone dehiscence and consequently the marginal gingiva can migrate apically, leading to root exposure.8,9 Moreover, orthodontic patients are strongly advised to prevent plaque
Medium
Thick
Very thick
accumulation around orthodontic appliances. Intensive tooth brushing, however, may contribute to mechanical destruction of gingival tissue, particularly if a habit of vigorous tooth cleaning continues indefinitely. On the other hand, in case of inadequate plaque removal around a fixed orthodontic appliance, gingival inflammation could lead to periodontal breakdown. Subjects with thin periodontal biotype were considered more susceptible to gingival recessions than patients with thick biotype.10 The thick tissue biotype has been considered an important factor for a successful outcome in root coverage procedures,11,12 implant restoration,13
Fig 1c The tip of the periodontal biotype probe is thin so as to not damage the marginal periodontal tissues and for better patient comfort.
Fig 2 Thin: The white color of the probe is clearly visible through the tissue. Medium: The green portion of the probe is clearly visible through the tissue, and the white tip is not visible. Thick: The blue is clearly visible through the tissue, but neither the white nor the green is visible. Very thick: The blue, and consequently the other two colors, also are not visible through the tissue. • = colored tip is visible through the gingival tissue; x = colored tip is not visible through the gingival tissue.
and orthodontic treatment.14,15 Thus, a careful pretreatment evaluation of the buccolingual thickness of gingival tissue should be suggested to avoid such mucogingival defects. To the best of the authors’ knowledge, no studies have explained the possible correlation between soft tissue thickness and the occurrence of gingival recessions during active orthodontic treatment. The aim of this preliminary investigation was to assess the effect of periodontal biotype on root surface exposure during orthodontic treatment, and to test the clinical usefulness of a new device in making a qualitative assessment of the gingival thickness.
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
667 Method and materials Patient and site selection
Sixteen subjects waiting for orthodontic treatment with fixed appliances were selected to participate in this study at the Department of Orthodontics of the University of Milan. A screening examination revealed that all patients had an unremarkable medical history, and none had gingival recessions or restorations at the mandibular incisors. To be included in the present investigation, patients had to be nonsmokers, and female subjects could not be pregnant or breastfeeding. Patients who had been previously treated with orthodontic fixed appliances and/or surgical or nonsurgical periodontal treatment were excluded, as well as subjects taking medications associated with gingival enlargement (ie, cyclosporine A, phenytoin, or calcium channel blockers).
Clinical examination of the study sample
The clinical examination was focused on the four mandibular incisors (64 incisor-type teeth, 32 lateral incisors, and 32 central incisors), because these teeth are more prone to developing gingival recessions.14–16 The baseline clinical evaluation was performed the day of banding just before the orthodontic appliance was placed. The following clinical periodontal parameters were considered: probing pocket depth (PPD), recession depth (RD), clinical attachment level (CAL), keratin-
a
b
c
d
e
f
Fig 3 Periodontal biotype evaluation using the biotype probe. All three colored tips are visible through the gingival margin. The periodontal biotype can be classified as thin.
ized tissue width (KTW), full-mouth bleeding score (FMBS; bleeding on probing, evaluated as six sites per tooth on all maxillary and mandibular teeth),17 and full-mouth plaque score (FMPS).18 All these clinical periodontal parameters were reevaluated 9 months after orthodontic treatment was instituted.
probe (Hu-Friedy) (Figs 1 and 2), to differentiate the thickness of gingival tissue in four categories: •
•
Periodontal biotype qualitative assessment
• The baseline estimation of soft tissue biotype was established through the use of the biotype
Thin biotype: Once inserted into the sulcus, the white color of the probe is clearly visible through the tissue (Fig 3). Medium biotype: The green portion of the probe is clearly visible through the tissue, and the white one is not visible (Fig 4). Thick biotype: The blue is clearly visible through the tissue, but neither the white nor the green part is visible (Fig 5).
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
668
a
b
c
d
e
f
Fig 4 Periodontal biotype evaluation using the biotype probe. The white tip is not visible through the gingival margin (a,b) while the green (c,d) and blue (e,f) parts are visible. The periodontal biotype can be classified as medium.
•
Very thick biotype: The blue, and consequently also the other two colors, are not visible through the tissue (Fig 6).
Oral hygiene instructions and maintenance care program
All patients enrolled in the present study underwent full-mouth etiologic therapy, including supragingival tooth cleaning with ultrasonic devices, tooth polishing with a rubber cup, and oral hygiene instructions on brushing and flossing
teeth in the presence of orthodontic appliances. No orthodontic fixed appliance was placed until the patient showed FMPS and FMBS values less than 25%. During the orthodontic treatment, patients were recalled every month to check and correct any mistakes in the brushing and flossing technique, until the final 9-month follow-up examination.
Statistical analysis
The characteristics of the sample at baseline were presented in terms of
mean value and standard deviation; clinical parameters were expressed in millimeters, except for FMBS and FMPS values, which were expressed as percentages. The quantitative variation of clinical parameters was performed with the Student t test, and the chi-square test was used to compare the changes between percentage values. Analysis of variance, followed by the use of the Tukey post hoc test, was performed to investigate the changes in clinical parameters in relation to periodontal biotype and orthodontic movement (α = .05). Multiple linear regression analysis was performed to evaluate the correlation between periodontal biotype and orthodontic movement. The strength of the correlation was determined by R value: a value greater than 0.70 was considered a strong correlation; values between 0.40 and 0.70 were considered moderate; and less than 0.40 was considered mild. Statistical analysis was conducted using the software JMP (version 5.0.1a, SAS). Statistical significance was set at a value of α < .05.
Results Baseline patient characteristics
Demographic characteristics of the subject population at baseline are presented in Table 1. The mean age of patients enrolled in the study was 21 ± 8.20 years, with a range of 14 to 38 years old; 10 subjects were male and 6 female. Regarding the type of orthodontic movement, six patients were characterized as
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
669 undergoing proinclination of the mandibular incisors, five as undergoing retroinclination, and five as undergoing alignment.
Clinical periodontal parameters
Table 2 shows baseline and 9-month mean data for the clinical periodontal parameters assessed. All patients showed an acceptable standard of supragingival plaque control both at first (FMPS, 9.71% ± 14.90%; FMBS, 9.72% ± 6.99%) and final (FMPS, 9.43% ± 11.18%; FMBS, 16.61% ± 14.09%) examinations. The probing pocket depth remained shallow (1.45 ± 0.14 mm vs 1.96 ± 0.24 mm), and no statistical differences were noticed between the baseline and the 9-month follow-up examination values (P = .38). The CAL changed from 1.45 ± 0.14 mm to 2.03 ± 0.36 mm. The mean increase in CAL value, 0.06 ± 0.25, was not statistically significant (P = .43). The KTW changed from 4.23 ± 1.83 mm to 4.14 ± 1.96 mm, with a mean variation of –0.09 ± 1.75 mm (P < .001). No gingival recessions were detected during the baseline evaluation of the patients enrolled in the study. At the 9-month follow-up visit, only one patient showed a gingival recession of 1.5 mm on a mandibular left central incisor.
Periodontal biotype qualitative assessment
Using the biotype probes, the sample study was equally divided into the four periodontal biotype cat-
a
b
c
d
e
f
Fig 5 Periodontal biotype evaluation using the biotype probe. The white (a,b) and green (c,d) tips are not visible through the gingival margin, and the blue parts are visible (e,f). The periodontal biotype can be classified as thick.
egories (four each of thin, medium, thick, and very thick types). The distribution of periodontal biotype categories in relation to orthodontic movement is presented in Fig 7.
Periodontal biotype influence on clinical variables
PPD and CAL Changes in PPD and CAL values in relation to periodontal biotype are summed up in Table 3. An increase in the PPD value was observed in all biotype categories; these differ-
ences were not statistically significant (F = 1.66, P = .23). As well as PPD, no statistically significant differences were found among the four biotype groups, both at baseline (F = 0.22, P = 0.88) and 9-month follow-up visit (F = 1.50, P = 0.26) in terms of CAL. An increase in the CAL value was observed in all biotype categories, but these differences were not statistically significant (F = 1.25, P = 0.33). RD and KTW Changes in RD and KTW values in relation to periodontal biotype are summed up in Table 3. Only one
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
670
Table 1 Baseline patient characteristics Parameters Mean ± SD age (y)
21 ± 8.20
Sex (%) a
Male Female
b
10 (66.67) 6 (33.33)
Canine class (%) Class I Class II Class III
5 (31.25) 6 (37.50) 5 (31.25)
Skeletal class (%)
c
Class I Class II Class III
d
5 (31.25) 6 (37.50) 5 (31.25)
Orthodontic movement Alignment Proinclination Retroinclination
5 (31.25) 6 (37.50) 5 (31.25)
SD = standard deviation.
e
f
Fig 6 Periodontal biotype evaluation using the biotype probe. All three colored tips are not visible through the gingival margin. The periodontal biotype can be classified as very thick.
Table 2 Changes in clinical periodontal parameters Parameters
Baseline*
9-month*
𝚫*
P
FMPS (%) FMBS (%) PPD (mm) CAL (mm)
9.71 ± 14.90 9.72 ± 6.99 1.45 ± 0.14 1.45 ± 0.14
9.43 ± 11.18 16.61 ± 14.09 1.96 ± 0.24 2.03 ± 0.36
–0.28 ± 10.1 6.89 ± 9.20 0.51 ± 0.17 0.06 ± 0.25
.41 .38 .45 .43
RD (mm) KTW (mm)
0.00 4.23 ± 1.83
0.06 ± 0.26 4.14 ± 1.96
0.57 ± 0.26 –0.09 ± 1.75
NSS < .001**
*Mean ± standard deviation. **Statistically significant difference (P < .05). FMPS = full mouth plaque score; FMBS = full mouth bleeding score; PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; NSS = not statistically significant.
patient experienced a root surface exposure of 1 mm during the orthodontic treatment (F = 1.00, P = 0.43). No statistically significant differences
were found in KTW values among the four biotype groups, either at baseline (F = 0.44, P = .73) or at the 9-month follow-up visit (F = 0.08,
P = .97). A statistically significant loss of KTW was observed in patients with thin biotype (F = 2.57, P = .03).
Orthodontic movement influence on clinical variables
PPD and CAL Changes in PPD and CAL values in relation to orthodontic movement are summed up in Table 4. An increase in the PPD value was observed in all orthodontic movement categories but these differences were not statistically significant (F = 0.71, P = .51). As well as PPD, no statistical differences were found
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
671
Thin Medium Thick Very thick
a
Thin Medium Thick Very thick
b
Thin Medium Thick Very thick
c
Fig 7 Periodontal biotype distribution: (a) Alignment; (b) Pro-inclination; (c) Retro-inclination.
Table 3 Periodontal biotype impact on periodontal clinical indexes PPD (mm) Baseline 9-month ∆ CAL (mm) Baseline 9-month ∆ RD (mm) Baseline 9-month ∆ KTW (mm) Baseline 9-month ∆
Thin*
Medium*
Thick*
Very thick*
F ratio (P)*
1.44 (0.14) 2.15 (0.31) 0.71 (0.32)
1.48 (0.16) 1.93 (0.14) 0.45 (0.26)
1.41 (0.15) 1.76 (0.23) 0.36 (0.14)
1.47 (0.13) 1.95 (0.14) 0.48 (0.17)
0.22 (.88) 2.11 (.15) 1.66 (.23)
1.44 (0.14) 2.15 (0.31) 0.71 (0.32)
1.48 (0.16) 1.93 (0.14) 0.45 (0.26)
1.41 (0.15) 1.76 (0.23) 0.36 (0.14)
1.47 (0.13) 2.20 (0.52) 0.73 (0.52)
0.22 (.88) 1.50 (.26) 1.25 (.33)
0.00 (0.00) 0.25 (0.50 0.25 (0.50
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
NSS 1.00 (.43) 1.00 (.43)
4.81 (2.53) 4.31 (3.21) –0.50 (0.71)
4.56 (2.75) 4.31 (2.63) –0.25 (0.46)
3.75 (0.35) 3.69 (0.24) –0.06 (0.31)
3.50 (0.61) 3.96 (0.68) 0.46 (0.47)
0.44 (.73) 0.08 (.97) 2.57 (.03)**
*Mean ± standard deviation. **Statistically significant difference (P < .05). PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; NSS = not statisticaly significant.
in CAL values among the three orthodontic movements both at baseline (F = 0.08, P = .92) and 9-month follow-up visit (F = 1.07, P = .37). The increase in the CAL value observed during orthodontic treatment was not statistically significant (F = 1.42, P = .28). RD and KTW Changes in RD and KTW values in relation to orthodontic movement are summed up in Table 4. Only
one patient experienced a root surface exposure after a proinclination of the mandibular incisors (F = .81, P = .47). No statistically significant differences were found in KTW values in relation to the type of orthodontic movement, either at baseline (F = 0.13, P = .88) or at the 9-month follow-up visit (F = 0.91, P = .43). A statistically significant loss of KTW was observed in subjects treated with proinclination of the mandibular incisors (F = 16.52, P = .003).
Correlation between periodontal biotype and orthodontic movement
No significant relationship was observed between periodontal biotype and orthodontic movement regarding variations of PPD and CAL values (Figs 8a and 8b). A strong correlation was found between thin biotype and proinclination orthodontic movement in terms of RD (R = 0.83; P = .001) (Fig 8c) and KTW (R = 0.87;
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
672
Table 4 Orthodontic movement impact on periodontal clinical indexes Alignment* PPD (mm) Baseline 9-month ∆ CAL (mm) Baseline 9-month ∆ RD (mm) Baseline 9-month ∆ KTW (mm) Baseline 9-month ∆
Proinclination* Retroinclination*
F ratio (P)*
1.45 (0.13) 1.98 (0.30) 0.53 (0.23)
1.43 (1.42) 1.99 (0.10) 0.56 (0.24)
1.47 (0.15) 1.85 (0.11) 0.39 (0.11)
0.08 (.92) 0.50 (.62) 0.71 (.51)
1.45 (0.13) 1.98 (0.30) 0.53 (0.25)
1.43 (0.14) 2.16 (0.43) 0.73 (0.43)
1.47 (0.15) 1.85 (0.28) 0.39 (0.28)
0.08 (.92) 1.07 (.37) 1.42 (.28)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
0.00 (0.00) 0.17 (0.41) 0.17 (0.40)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
NSS 0.81 (.47) 0.81 (.47)
3.90 (0.85) 3.95 (0.87) 0.05 (0.43)
4.08 (0.78) 3.42 (0.78) –0.67 (0.30)
4.50 (0.85) 4.97 (0.87) 0.46 (0.21)
0.13 (.88) 0.91 (.43) 16.52 (.003)**
*Mean ± standard deviation. **Statistically significant difference (P < .05). PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; NSS= not statistically significant.
P = .001) (Fig 8d). A moderate correlation existed between thin and medium biotype with orthodontic alignment (R = 0.60, P < .05 and R = .48, P < .05, respectively) and between medium biotype and proinclination (R = 0.54; P < .05) (Fig 8d).
Discussion An understanding of the association between orthodontic treatment and the development of gingival recessions is important because more and more children, teenagers, and adults are being treated orthodontically.19 For example, data show that the proportion of US children who received orthodontic therapy increased from about 15% in the 1950s to more than 30% in the 1970s.19 Furthermore, most patients
desire orthodontic treatment for esthetic reasons.20 This motivation is independent of the geographic location or the affluence of the country.21 However, gingival recessions can negatively affect the esthetics of the dentition and compromise treatment results. Orthodontic appliances are a potential factor of mechanical and chemical irritation for periodontal tissues, creating retention areas for dental plaque; even when oral hygiene is excellent in the visible part of the tooth, the device causes a change in the intraoral microflora, leading to a bacterial array similar to that present in sites affected by periodontal disease.22 The present findings show that even when patients were engaged in optimal plaque control (FMPS, –0.28% ± 10.1%; P = .31), an increase in FMBS (6.89%
± 9.20%; P = .48) and PPD (0.51 ± 0.17 mm; P = .45) was observed 9 months after the orthodontic treatment was initiated. Although these differences were not statistically significant, they may support the clinical effect of fixed orthodontic appliance on periodontal status. In contrast to patients with a clear thick gingiva, those with a thin-scalloped biotype are considered at risk; an accurate identification of these high-risk subjects is warranted. Usually, simple visual inspection is used in clinical practice and even in research to identify these high-risk patients; however, the precision of this method has never been documented. Egbhali et al23 observed that, by means of a visual evaluation of gingival thickness, the biotype was accurately identified in only about half of the cases irrespective of the clinician’s experience. Experienced clinicians mostly recognized the thick flat biotype while nearly half of the thin scalloped cases were misclassified. As a result, simple visual inspection may not be considered a valuable method to identify the gingival biotype. In contrast to visual inspection, many instrumental methods were proposed to measure tissue thickness: direct measurements,24 probe transparency,13 ultrasonic devices,25 and, most recently, cone beam computed tomography (CBCT).26 In the direct method, the tissue thickness was measured using a periodontal probe.24 When the thickness was 1.5 mm or more, it was categorized as a thick biotype. When the thickness was less than 1.5 mm, it was considered a thin
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
673
0.4 Thin
0.7
0.4
0.7
AL
P = .48
P = .23
AL
PI
P = .97
P = .86
PI
RI
P = .28
P = .48
RI
Thick
∆ PPD
Medium
AL
P = .17
P = .43
AL
PI
P = .57
P = .89
PI
P = .43
P = .41
RI Mild
a
Moderate
0.4 Thin
Strong
Very thick
RI Mild
0.7
Moderate
0.4
Strong
0.7
AL
P = .82
P = .48
AL
PI
P = .72
P = .36
PI
RI
P = .12
P = .95
RI
Thick
∆ CAL
Medium
AL
P = .25
P = .44
AL
PI
P = .61
P = .36
PI
P = .18
P = .16
RI Mild
b
Moderate
0.4 Thin
Strong
Very thick
RI Mild
0.7
Moderate
0.4
Strong
0.7
AL
P = NSS
P = NSS
AL
PI
P = .001
P = NSS
PI
RI
P = NSS
P = NSS
RI
Thick
∆ RD
Medium
AL
P = NSS
P = NSS
AL
PI
P = NSS
P = NSS
PI
P = NSS
P = NSS
RI Mild
c
Moderate
0.4 Thin
Strong
Very thick
RI Mild
0.7
Moderate
0.4
Strong
0.7
AL
P = < .05
P = .41
AL
PI
P = .001
P = .16
PI
RI
P = .28
P = .85
RI
Thick
∆ KTW
Medium
AL
P = < .05
P = .38
AL
PI
P = < .05
P = .16
PI
P = .48
P = .43
RI d
Mild
Moderate
Strong
Very thick
RI Mild
Moderate
Strong
Fig 8 Regression analysis. PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; AL = alignment; PI = proinclination; RI = retroinclination. Statistically significant values are reported in red type.
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
674
tissue biotype. However, this method of measurement had several inherent limitations, such as the precision of the probe, which is to the nearest 0.5 mm; the angulation of the probe during the transgingival probing; and the distortion of the tissue during probing. In the probe transparency technique, the gingival biotype was considered thin when the outline of the periodontal probe showed through the gingival margin from inside the sulcus.13 The biotype was considered thick if the probe did not show through the gingival margin. Müller et al25 applied a noninvasive ultrasonic device to measure gingival thickness. This method had several limitations; most importantly, it was difficult to determine the correct position and attain reproducible measurements. Recently, CBCT scans were used to visualize and measure the thickness of both hard and soft tissues.26 Although a recent study demonstrated that CBCT measurements were an accurate representation of the clinical thickness of the labial gingiva,27 the cost and benefit ratio should be careful evaluated. The biotype probes used in the present study represent a new way to objectively assess the quality of the periodontal tissues with an easy-touse, biologically noninvasive, and low-cost device. Dorfman28 reported that, in his study, 16 patients with decreased KTW demonstrated marked gingival recession. Their incisors moved either negligibly or somewhat proinclinated during treatment. However, the eight patients with increase in
KTW exhibited a relevant amount of retroinclination tooth movement. The results of the present investigation showed a statistically significant reduction in the KTW value in the thin-biotype group (–0.50 ± 0.71 mm; F = 2.57; P = .03), and the proinclination orthodontic movement was significantly associated with a reduction in the KTW (–0.67 ± 0.30 mm; F = 16.52; P = .003). Melsen and Allais9 compared the gingival situation of their patients before and after treatment with a fixed appliance and proinclination of mandibular incisors. They demonstrated that the increase in the prevalence of gingival recession during treatment was significant, but the increase in the mean gingival recession was not significant. Moreover, four variables were significantly related with the development or increase in the gingival recession during orthodontic treatment: baseline recession presence, KTW, periodontal biotype, and visual gingival inflammation.9 Although no statistical significance was observed, only one of the 16 subjects enrolled in that study who experienced the development of a gingival recession had a thin periodontal biotype and was orthodontically treated with proinclination of the mandibular incisors. KTW values in relation to the type of orthodontic movement were in agreement with those found by Andlin-Sobocki.29 When teeth were retroinclined, the KTW increased (0.46 ± 0.21 mm), whereas a loss of KTW was observed when the mandibular incisors were proinclined (–0.67 ± 0.30 mm).
A recent review failed to clarify the effect of orthodontic changes in incisor inclination on the occurrence of gingival recession.16 However, a strong and positive correlation was found between proinclination and thin biotype, both in terms of RD (R = 0.83; P = .001) and KTW (R = 0.87; P = 0.001).
Conclusions Within the limits of the present study, the periodontal biotype should be properly identified before orthodontic treatment to avoid the development of gingival recession. When gingival biotype is thin, all types of orthodontic movements seem to be unfavorable, leading to a loss of KTW and increasing the risk of gingival recession. Among the different types of movements, proinclination was always related to a loss of soft gingival tissue; the thinner the biotype, the higher the KTW loss. The use of the biotype probe is a reliable, friendly, and noninvasive way to classify the periodontal biotype.
Acknowledgment We are grateful to Hu-Friedy Company (Chicago, IL) for providing the biotype probes used in the study. Dr Giulio Rasperini did not participate in the data collection and data analysis, and does declare a financial interest with the biotype probe produced by Hu-Friedy. No other author declares any conflict of interest.
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
675
References 1. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol 1999;4:1–6. 2. Löe H, Anerud A, Boysen H. The natural history of periodontal disease in man: Prevalence, severity, and extent of gingival recession. J Periodontol 1992; 63:489–495. 3. Khocht A, Simon G, Person P, Denepitiya JL. Gingival recession in relation to history of hard toothbrush use. J Periodontol 1993;64:900–905. 4. Sardella A, Pedrinazzi M, Bez C, Lodi G, Carrassi A. Labial piercing resulting in gingival recession. A case series. J Clin Periodontol 2002;29:961–963. 5. Levin L, Zadik Y, Becker T. Oral and dental complications of intraoral piercing. Dent Traumatol 2005;21:341–343. 6. Abboud M, Grüner M, Koeck B. Anterior crowding-just an esthetic problem? J Orofac Orthop 2002;63:264–273. 7. Trossello VK, Gianelly AA. Orthodontic treatment and periodontal status. J Periodontol 1979;50:665–671. 8. Renkema AM, Fudalej PS, Renkema AAP, Abbas F, Bronkhorst E, Katsaros C. Gingival labial recessions in orthodontically treated and untreated individuals: A pilot case–control study. J Clin Periodontol 2013;40:631–637. 9. Melsen B, Allais D. Factors of importance for the development of dehiscences during labial movement of mandibular incisors: A retrospective study of adult orthodontic patients. Am J Orthod Dentofacial Orthop 2005;127: 552–561. 10. Olsson M, Lindhe J. Periodontal characteristics in individuals with varying form of the upper central incisors. J Clin Periodontol 1991;18:78–82.
11. Baldi C, Pini-Prato G, Pagliaro U, et al. Coronally advanced flap procedure for root coverage. Is flap thickness a relevant predictor to achieve root coverage? A 19-case series. J Periodontol 1999;70: 1077–1784. 12. Cairo F, Pagliaro U, Nieri M. Treatment of gingival recession with coronally advanced flap procedures: A systematic review. J Clin Periodontol 2008;35(suppl 8): 136–162. 13. Kan JY, Rungcharassaeng K, Umezu K, Kois JC. Dimensions of peri-implant mucosa: An evaluation of maxillary anterior single implants in humans. J Periodontol 2003;74:557–562. 14. Aziz T, Flores-Mir C. A systematic review of the association between applianceinduced labial movement of mandibular incisors and gingival recession. Aust Orthod J 2011;27:33–39. 15. Vasconcelos G, Kjellsen K, Preus H, Vandevska-Radunovic V, Hansen BF. Prevalence and severity of vestibular recession in mandibular incisors after orthodontic treatment. Angle Orthod 2012; 82:42–47. 16. Joss-Vassalli I, Grebenstein C, Topouzelis N, Sculean A, Katsaros C. Orthodontic therapy and gingival recession: A systematic review. Orthod Craniofac Res 2010;13:127–141. 17. Ainamo J, Bay I. Problems and proposal for recording gingivitis and plaque. Int Dent J 1975;25:229–235. 18. O’Leary TJ, Drake RB, Naylor JE. The plaque control record. J Periodontol 1972;43:38. 19. Bollen AM, Cunha-Cruz J, Hujoel PP. Secular trends in preadult orthodontic care in the United States: 1942–2002. Am J Orthod Dentofacial Orthop 2007; 132:579–585.
20. Wedrychowska-Szulc B, Syrynska M. Patient and parent motivation for orthodontic treatment: A questionnaire study. Eur J Orthod 2010;32:447–452. 21. Khan M, Fida M. Assessment of psychosocial impact of dental aesthetics. J Coll Physicians Surg Pak 2008;18:559–564. 22. Reichert C, Hagner M, Jepsen S, Jäger A. Interfaces between orthodontic and periodontal treatment. J Orofac Orthop 2011;72:165–186. 23. Eghbali A, De Rouck T, De Bruyn H, Cosyn J. The gingival biotype assessed by experienced and inexperienced clinicians. J Clin Periodontol 2009;36: 958–963. 24. Greenberg J, Laster L, Listgarten MA. Transgingival probing as a potential estimator of alveolar bone level. J Periodontol 1976;47:514–517. 25. Müller HP, Heinecke A, Schaller N, Eger T. Masticatory mucosa in subjects with different periodontal phenotypes. J Clin Periodontol 2000;27:621–626. 26. Barriviera M, Duarte WR, Januário AL, Faber J, Bezerra AC. A new method to assess and measure palatal masticatory mucosa by cone-beam computerized tomography. J Clin Periodontol 2009; 36:564–568. 27. Fu JH, Yeh CY, Chan HL, Tatarakis N, Leong DJ, Wang HL. Tissue biotype and its relation to the underlying bone morphology. J Periodontol. 2010;81:569–574. 28. Dorfman HS. Mucogingival changes resulting from mandibular incisor tooth movement. Am J Orthod 1978;74: 286–297. 29. Andlin-Sobocki A. Changes of facial gingival dimensions in children: A 2-year longitudinal study. J Clin Periodontol 1993; 20:212–218.
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
665
Influence of Periodontal Biotype on Root Surface Exposure During Orthodontic Treatment: A Preliminary Study Giulio Rasperini, DDS1 Raffaele Acunzo, DDS2 Paola Cannalire, DDS3 Giampietro Farronato, MD, DDS4
The aim of this study was to investigate the role of periodontal biotype in the development of gingival recession in patients who have undergone orthodontic treatment. A total of 60 mandibular incisors were analyzed. The qualitative assessment of periodontal biotype was performed with the use of a new biotype probe. A strong correlation was found between thin biotype and proinclination in terms of recession depth and keratinized tissue width. Patients with thin periodontal biotype are more prone to gingival margin instability, irrespective of the type of orthodontic movements. Thin periodontal biotype and proinclination orthodontic movement were related to loss of keratinized tissue width. (Int J Periodontics Restorative Dent 2015;35:665–675. doi: 10.11607/prd.2239)
Professor, Unit of Periodontology, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 2Research Fellow, Unit of Periodontology, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 3Graduate Resident, Unit of Periodontology, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 4Professor of Orthodontics, Department of Biomedical, Surgical and Dental Sciences, University of Milan, Fundation IRCCS Ca’ Granda Policlinic, Milan, Italy. 1
Correspondence to: Dr Raffaele Acunzo, Via Monte Grappa 12, 20126 Novate, Milan, Italy. Fax +39-02-3512986. Email: [email protected] ©2015 by Quintessence Publishing Co Inc.
According to the International Workshop for a Classification of Periodontal Diseases and Conditions, the gingival/soft tissue recessions on the vestibular or lingual surfaces or interproximal (papillary) areas are classified in the group of “development or acquired mucogingival deformities and conditions around teeth”1 and are defined as the displacement of the marginal tissue apical to the cementoenamel junction. The resulting root exposure is not esthetically pleasing and may lead to dentinal sensitivity and root caries. The occurrence of gingival recessions is age-dependent and their development begins relatively early in life.2 Gingival recessions were noticed in more than 60% of Norwegian 20-year-olds and in more than 90% of the older population (> 50 years);2 in populations deprived of dental care, the occurrence of root exposures was even higher.2 Although its etiology is unclear, periodontal disease and mechanical trauma are considered the primary factors in the pathogenesis of gingival recession defects. Traumatic tooth brushing,3 intra- and perioral piercings,4 bruxism,5 and microbiologically induced inflammation in periodontal connective tissue6 have been proposed as the most important factors. Consanguinity between orthodontic
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
666 Fig 1 Periodontal biotype probes from different views.
a
b
c
Figs 1a and 1b A qualitative assessment of the gingival thickness can be performed to evaluate the visibility of the colored tip of the probe through the gingival tissue.
Thin
tooth movement and gingival recession has also been a common anecdotal observation in the periodontic and orthodontic literature.7 However, experimental evidence suggests that orthodontic tooth movement does not actually cause gingival recession but might create an environment that predisposes some people to the condition. Orthodontic tooth movement can result in root positions near or outside the labial or lingual alveolar bone plate; this can lead to bone dehiscence and consequently the marginal gingiva can migrate apically, leading to root exposure.8,9 Moreover, orthodontic patients are strongly advised to prevent plaque
Medium
Thick
Very thick
accumulation around orthodontic appliances. Intensive tooth brushing, however, may contribute to mechanical destruction of gingival tissue, particularly if a habit of vigorous tooth cleaning continues indefinitely. On the other hand, in case of inadequate plaque removal around a fixed orthodontic appliance, gingival inflammation could lead to periodontal breakdown. Subjects with thin periodontal biotype were considered more susceptible to gingival recessions than patients with thick biotype.10 The thick tissue biotype has been considered an important factor for a successful outcome in root coverage procedures,11,12 implant restoration,13
Fig 1c The tip of the periodontal biotype probe is thin so as to not damage the marginal periodontal tissues and for better patient comfort.
Fig 2 Thin: The white color of the probe is clearly visible through the tissue. Medium: The green portion of the probe is clearly visible through the tissue, and the white tip is not visible. Thick: The blue is clearly visible through the tissue, but neither the white nor the green is visible. Very thick: The blue, and consequently the other two colors, also are not visible through the tissue. • = colored tip is visible through the gingival tissue; x = colored tip is not visible through the gingival tissue.
and orthodontic treatment.14,15 Thus, a careful pretreatment evaluation of the buccolingual thickness of gingival tissue should be suggested to avoid such mucogingival defects. To the best of the authors’ knowledge, no studies have explained the possible correlation between soft tissue thickness and the occurrence of gingival recessions during active orthodontic treatment. The aim of this preliminary investigation was to assess the effect of periodontal biotype on root surface exposure during orthodontic treatment, and to test the clinical usefulness of a new device in making a qualitative assessment of the gingival thickness.
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
667 Method and materials Patient and site selection
Sixteen subjects waiting for orthodontic treatment with fixed appliances were selected to participate in this study at the Department of Orthodontics of the University of Milan. A screening examination revealed that all patients had an unremarkable medical history, and none had gingival recessions or restorations at the mandibular incisors. To be included in the present investigation, patients had to be nonsmokers, and female subjects could not be pregnant or breastfeeding. Patients who had been previously treated with orthodontic fixed appliances and/or surgical or nonsurgical periodontal treatment were excluded, as well as subjects taking medications associated with gingival enlargement (ie, cyclosporine A, phenytoin, or calcium channel blockers).
Clinical examination of the study sample
The clinical examination was focused on the four mandibular incisors (64 incisor-type teeth, 32 lateral incisors, and 32 central incisors), because these teeth are more prone to developing gingival recessions.14–16 The baseline clinical evaluation was performed the day of banding just before the orthodontic appliance was placed. The following clinical periodontal parameters were considered: probing pocket depth (PPD), recession depth (RD), clinical attachment level (CAL), keratin-
a
b
c
d
e
f
Fig 3 Periodontal biotype evaluation using the biotype probe. All three colored tips are visible through the gingival margin. The periodontal biotype can be classified as thin.
ized tissue width (KTW), full-mouth bleeding score (FMBS; bleeding on probing, evaluated as six sites per tooth on all maxillary and mandibular teeth),17 and full-mouth plaque score (FMPS).18 All these clinical periodontal parameters were reevaluated 9 months after orthodontic treatment was instituted.
probe (Hu-Friedy) (Figs 1 and 2), to differentiate the thickness of gingival tissue in four categories: •
•
Periodontal biotype qualitative assessment
• The baseline estimation of soft tissue biotype was established through the use of the biotype
Thin biotype: Once inserted into the sulcus, the white color of the probe is clearly visible through the tissue (Fig 3). Medium biotype: The green portion of the probe is clearly visible through the tissue, and the white one is not visible (Fig 4). Thick biotype: The blue is clearly visible through the tissue, but neither the white nor the green part is visible (Fig 5).
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
668
a
b
c
d
e
f
Fig 4 Periodontal biotype evaluation using the biotype probe. The white tip is not visible through the gingival margin (a,b) while the green (c,d) and blue (e,f) parts are visible. The periodontal biotype can be classified as medium.
•
Very thick biotype: The blue, and consequently also the other two colors, are not visible through the tissue (Fig 6).
Oral hygiene instructions and maintenance care program
All patients enrolled in the present study underwent full-mouth etiologic therapy, including supragingival tooth cleaning with ultrasonic devices, tooth polishing with a rubber cup, and oral hygiene instructions on brushing and flossing
teeth in the presence of orthodontic appliances. No orthodontic fixed appliance was placed until the patient showed FMPS and FMBS values less than 25%. During the orthodontic treatment, patients were recalled every month to check and correct any mistakes in the brushing and flossing technique, until the final 9-month follow-up examination.
Statistical analysis
The characteristics of the sample at baseline were presented in terms of
mean value and standard deviation; clinical parameters were expressed in millimeters, except for FMBS and FMPS values, which were expressed as percentages. The quantitative variation of clinical parameters was performed with the Student t test, and the chi-square test was used to compare the changes between percentage values. Analysis of variance, followed by the use of the Tukey post hoc test, was performed to investigate the changes in clinical parameters in relation to periodontal biotype and orthodontic movement (α = .05). Multiple linear regression analysis was performed to evaluate the correlation between periodontal biotype and orthodontic movement. The strength of the correlation was determined by R value: a value greater than 0.70 was considered a strong correlation; values between 0.40 and 0.70 were considered moderate; and less than 0.40 was considered mild. Statistical analysis was conducted using the software JMP (version 5.0.1a, SAS). Statistical significance was set at a value of α < .05.
Results Baseline patient characteristics
Demographic characteristics of the subject population at baseline are presented in Table 1. The mean age of patients enrolled in the study was 21 ± 8.20 years, with a range of 14 to 38 years old; 10 subjects were male and 6 female. Regarding the type of orthodontic movement, six patients were characterized as
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
669 undergoing proinclination of the mandibular incisors, five as undergoing retroinclination, and five as undergoing alignment.
Clinical periodontal parameters
Table 2 shows baseline and 9-month mean data for the clinical periodontal parameters assessed. All patients showed an acceptable standard of supragingival plaque control both at first (FMPS, 9.71% ± 14.90%; FMBS, 9.72% ± 6.99%) and final (FMPS, 9.43% ± 11.18%; FMBS, 16.61% ± 14.09%) examinations. The probing pocket depth remained shallow (1.45 ± 0.14 mm vs 1.96 ± 0.24 mm), and no statistical differences were noticed between the baseline and the 9-month follow-up examination values (P = .38). The CAL changed from 1.45 ± 0.14 mm to 2.03 ± 0.36 mm. The mean increase in CAL value, 0.06 ± 0.25, was not statistically significant (P = .43). The KTW changed from 4.23 ± 1.83 mm to 4.14 ± 1.96 mm, with a mean variation of –0.09 ± 1.75 mm (P < .001). No gingival recessions were detected during the baseline evaluation of the patients enrolled in the study. At the 9-month follow-up visit, only one patient showed a gingival recession of 1.5 mm on a mandibular left central incisor.
Periodontal biotype qualitative assessment
Using the biotype probes, the sample study was equally divided into the four periodontal biotype cat-
a
b
c
d
e
f
Fig 5 Periodontal biotype evaluation using the biotype probe. The white (a,b) and green (c,d) tips are not visible through the gingival margin, and the blue parts are visible (e,f). The periodontal biotype can be classified as thick.
egories (four each of thin, medium, thick, and very thick types). The distribution of periodontal biotype categories in relation to orthodontic movement is presented in Fig 7.
Periodontal biotype influence on clinical variables
PPD and CAL Changes in PPD and CAL values in relation to periodontal biotype are summed up in Table 3. An increase in the PPD value was observed in all biotype categories; these differ-
ences were not statistically significant (F = 1.66, P = .23). As well as PPD, no statistically significant differences were found among the four biotype groups, both at baseline (F = 0.22, P = 0.88) and 9-month follow-up visit (F = 1.50, P = 0.26) in terms of CAL. An increase in the CAL value was observed in all biotype categories, but these differences were not statistically significant (F = 1.25, P = 0.33). RD and KTW Changes in RD and KTW values in relation to periodontal biotype are summed up in Table 3. Only one
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
670
Table 1 Baseline patient characteristics Parameters Mean ± SD age (y)
21 ± 8.20
Sex (%) a
Male Female
b
10 (66.67) 6 (33.33)
Canine class (%) Class I Class II Class III
5 (31.25) 6 (37.50) 5 (31.25)
Skeletal class (%)
c
Class I Class II Class III
d
5 (31.25) 6 (37.50) 5 (31.25)
Orthodontic movement Alignment Proinclination Retroinclination
5 (31.25) 6 (37.50) 5 (31.25)
SD = standard deviation.
e
f
Fig 6 Periodontal biotype evaluation using the biotype probe. All three colored tips are not visible through the gingival margin. The periodontal biotype can be classified as very thick.
Table 2 Changes in clinical periodontal parameters Parameters
Baseline*
9-month*
𝚫*
P
FMPS (%) FMBS (%) PPD (mm) CAL (mm)
9.71 ± 14.90 9.72 ± 6.99 1.45 ± 0.14 1.45 ± 0.14
9.43 ± 11.18 16.61 ± 14.09 1.96 ± 0.24 2.03 ± 0.36
–0.28 ± 10.1 6.89 ± 9.20 0.51 ± 0.17 0.06 ± 0.25
.41 .38 .45 .43
RD (mm) KTW (mm)
0.00 4.23 ± 1.83
0.06 ± 0.26 4.14 ± 1.96
0.57 ± 0.26 –0.09 ± 1.75
NSS < .001**
*Mean ± standard deviation. **Statistically significant difference (P < .05). FMPS = full mouth plaque score; FMBS = full mouth bleeding score; PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; NSS = not statistically significant.
patient experienced a root surface exposure of 1 mm during the orthodontic treatment (F = 1.00, P = 0.43). No statistically significant differences
were found in KTW values among the four biotype groups, either at baseline (F = 0.44, P = .73) or at the 9-month follow-up visit (F = 0.08,
P = .97). A statistically significant loss of KTW was observed in patients with thin biotype (F = 2.57, P = .03).
Orthodontic movement influence on clinical variables
PPD and CAL Changes in PPD and CAL values in relation to orthodontic movement are summed up in Table 4. An increase in the PPD value was observed in all orthodontic movement categories but these differences were not statistically significant (F = 0.71, P = .51). As well as PPD, no statistical differences were found
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
671
Thin Medium Thick Very thick
a
Thin Medium Thick Very thick
b
Thin Medium Thick Very thick
c
Fig 7 Periodontal biotype distribution: (a) Alignment; (b) Pro-inclination; (c) Retro-inclination.
Table 3 Periodontal biotype impact on periodontal clinical indexes PPD (mm) Baseline 9-month ∆ CAL (mm) Baseline 9-month ∆ RD (mm) Baseline 9-month ∆ KTW (mm) Baseline 9-month ∆
Thin*
Medium*
Thick*
Very thick*
F ratio (P)*
1.44 (0.14) 2.15 (0.31) 0.71 (0.32)
1.48 (0.16) 1.93 (0.14) 0.45 (0.26)
1.41 (0.15) 1.76 (0.23) 0.36 (0.14)
1.47 (0.13) 1.95 (0.14) 0.48 (0.17)
0.22 (.88) 2.11 (.15) 1.66 (.23)
1.44 (0.14) 2.15 (0.31) 0.71 (0.32)
1.48 (0.16) 1.93 (0.14) 0.45 (0.26)
1.41 (0.15) 1.76 (0.23) 0.36 (0.14)
1.47 (0.13) 2.20 (0.52) 0.73 (0.52)
0.22 (.88) 1.50 (.26) 1.25 (.33)
0.00 (0.00) 0.25 (0.50 0.25 (0.50
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
NSS 1.00 (.43) 1.00 (.43)
4.81 (2.53) 4.31 (3.21) –0.50 (0.71)
4.56 (2.75) 4.31 (2.63) –0.25 (0.46)
3.75 (0.35) 3.69 (0.24) –0.06 (0.31)
3.50 (0.61) 3.96 (0.68) 0.46 (0.47)
0.44 (.73) 0.08 (.97) 2.57 (.03)**
*Mean ± standard deviation. **Statistically significant difference (P < .05). PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; NSS = not statisticaly significant.
in CAL values among the three orthodontic movements both at baseline (F = 0.08, P = .92) and 9-month follow-up visit (F = 1.07, P = .37). The increase in the CAL value observed during orthodontic treatment was not statistically significant (F = 1.42, P = .28). RD and KTW Changes in RD and KTW values in relation to orthodontic movement are summed up in Table 4. Only
one patient experienced a root surface exposure after a proinclination of the mandibular incisors (F = .81, P = .47). No statistically significant differences were found in KTW values in relation to the type of orthodontic movement, either at baseline (F = 0.13, P = .88) or at the 9-month follow-up visit (F = 0.91, P = .43). A statistically significant loss of KTW was observed in subjects treated with proinclination of the mandibular incisors (F = 16.52, P = .003).
Correlation between periodontal biotype and orthodontic movement
No significant relationship was observed between periodontal biotype and orthodontic movement regarding variations of PPD and CAL values (Figs 8a and 8b). A strong correlation was found between thin biotype and proinclination orthodontic movement in terms of RD (R = 0.83; P = .001) (Fig 8c) and KTW (R = 0.87;
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
672
Table 4 Orthodontic movement impact on periodontal clinical indexes Alignment* PPD (mm) Baseline 9-month ∆ CAL (mm) Baseline 9-month ∆ RD (mm) Baseline 9-month ∆ KTW (mm) Baseline 9-month ∆
Proinclination* Retroinclination*
F ratio (P)*
1.45 (0.13) 1.98 (0.30) 0.53 (0.23)
1.43 (1.42) 1.99 (0.10) 0.56 (0.24)
1.47 (0.15) 1.85 (0.11) 0.39 (0.11)
0.08 (.92) 0.50 (.62) 0.71 (.51)
1.45 (0.13) 1.98 (0.30) 0.53 (0.25)
1.43 (0.14) 2.16 (0.43) 0.73 (0.43)
1.47 (0.15) 1.85 (0.28) 0.39 (0.28)
0.08 (.92) 1.07 (.37) 1.42 (.28)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
0.00 (0.00) 0.17 (0.41) 0.17 (0.40)
0.00 (0.00) 0.00 (0.00) 0.00 (0.00)
NSS 0.81 (.47) 0.81 (.47)
3.90 (0.85) 3.95 (0.87) 0.05 (0.43)
4.08 (0.78) 3.42 (0.78) –0.67 (0.30)
4.50 (0.85) 4.97 (0.87) 0.46 (0.21)
0.13 (.88) 0.91 (.43) 16.52 (.003)**
*Mean ± standard deviation. **Statistically significant difference (P < .05). PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; NSS= not statistically significant.
P = .001) (Fig 8d). A moderate correlation existed between thin and medium biotype with orthodontic alignment (R = 0.60, P < .05 and R = .48, P < .05, respectively) and between medium biotype and proinclination (R = 0.54; P < .05) (Fig 8d).
Discussion An understanding of the association between orthodontic treatment and the development of gingival recessions is important because more and more children, teenagers, and adults are being treated orthodontically.19 For example, data show that the proportion of US children who received orthodontic therapy increased from about 15% in the 1950s to more than 30% in the 1970s.19 Furthermore, most patients
desire orthodontic treatment for esthetic reasons.20 This motivation is independent of the geographic location or the affluence of the country.21 However, gingival recessions can negatively affect the esthetics of the dentition and compromise treatment results. Orthodontic appliances are a potential factor of mechanical and chemical irritation for periodontal tissues, creating retention areas for dental plaque; even when oral hygiene is excellent in the visible part of the tooth, the device causes a change in the intraoral microflora, leading to a bacterial array similar to that present in sites affected by periodontal disease.22 The present findings show that even when patients were engaged in optimal plaque control (FMPS, –0.28% ± 10.1%; P = .31), an increase in FMBS (6.89%
± 9.20%; P = .48) and PPD (0.51 ± 0.17 mm; P = .45) was observed 9 months after the orthodontic treatment was initiated. Although these differences were not statistically significant, they may support the clinical effect of fixed orthodontic appliance on periodontal status. In contrast to patients with a clear thick gingiva, those with a thin-scalloped biotype are considered at risk; an accurate identification of these high-risk subjects is warranted. Usually, simple visual inspection is used in clinical practice and even in research to identify these high-risk patients; however, the precision of this method has never been documented. Egbhali et al23 observed that, by means of a visual evaluation of gingival thickness, the biotype was accurately identified in only about half of the cases irrespective of the clinician’s experience. Experienced clinicians mostly recognized the thick flat biotype while nearly half of the thin scalloped cases were misclassified. As a result, simple visual inspection may not be considered a valuable method to identify the gingival biotype. In contrast to visual inspection, many instrumental methods were proposed to measure tissue thickness: direct measurements,24 probe transparency,13 ultrasonic devices,25 and, most recently, cone beam computed tomography (CBCT).26 In the direct method, the tissue thickness was measured using a periodontal probe.24 When the thickness was 1.5 mm or more, it was categorized as a thick biotype. When the thickness was less than 1.5 mm, it was considered a thin
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
673
0.4 Thin
0.7
0.4
0.7
AL
P = .48
P = .23
AL
PI
P = .97
P = .86
PI
RI
P = .28
P = .48
RI
Thick
∆ PPD
Medium
AL
P = .17
P = .43
AL
PI
P = .57
P = .89
PI
P = .43
P = .41
RI Mild
a
Moderate
0.4 Thin
Strong
Very thick
RI Mild
0.7
Moderate
0.4
Strong
0.7
AL
P = .82
P = .48
AL
PI
P = .72
P = .36
PI
RI
P = .12
P = .95
RI
Thick
∆ CAL
Medium
AL
P = .25
P = .44
AL
PI
P = .61
P = .36
PI
P = .18
P = .16
RI Mild
b
Moderate
0.4 Thin
Strong
Very thick
RI Mild
0.7
Moderate
0.4
Strong
0.7
AL
P = NSS
P = NSS
AL
PI
P = .001
P = NSS
PI
RI
P = NSS
P = NSS
RI
Thick
∆ RD
Medium
AL
P = NSS
P = NSS
AL
PI
P = NSS
P = NSS
PI
P = NSS
P = NSS
RI Mild
c
Moderate
0.4 Thin
Strong
Very thick
RI Mild
0.7
Moderate
0.4
Strong
0.7
AL
P = < .05
P = .41
AL
PI
P = .001
P = .16
PI
RI
P = .28
P = .85
RI
Thick
∆ KTW
Medium
AL
P = < .05
P = .38
AL
PI
P = < .05
P = .16
PI
P = .48
P = .43
RI d
Mild
Moderate
Strong
Very thick
RI Mild
Moderate
Strong
Fig 8 Regression analysis. PPD = probing pocket depth; CAL = clinical attachment level; RD = recession depth; KTW = keratinized tissue width; AL = alignment; PI = proinclination; RI = retroinclination. Statistically significant values are reported in red type.
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
674
tissue biotype. However, this method of measurement had several inherent limitations, such as the precision of the probe, which is to the nearest 0.5 mm; the angulation of the probe during the transgingival probing; and the distortion of the tissue during probing. In the probe transparency technique, the gingival biotype was considered thin when the outline of the periodontal probe showed through the gingival margin from inside the sulcus.13 The biotype was considered thick if the probe did not show through the gingival margin. Müller et al25 applied a noninvasive ultrasonic device to measure gingival thickness. This method had several limitations; most importantly, it was difficult to determine the correct position and attain reproducible measurements. Recently, CBCT scans were used to visualize and measure the thickness of both hard and soft tissues.26 Although a recent study demonstrated that CBCT measurements were an accurate representation of the clinical thickness of the labial gingiva,27 the cost and benefit ratio should be careful evaluated. The biotype probes used in the present study represent a new way to objectively assess the quality of the periodontal tissues with an easy-touse, biologically noninvasive, and low-cost device. Dorfman28 reported that, in his study, 16 patients with decreased KTW demonstrated marked gingival recession. Their incisors moved either negligibly or somewhat proinclinated during treatment. However, the eight patients with increase in
KTW exhibited a relevant amount of retroinclination tooth movement. The results of the present investigation showed a statistically significant reduction in the KTW value in the thin-biotype group (–0.50 ± 0.71 mm; F = 2.57; P = .03), and the proinclination orthodontic movement was significantly associated with a reduction in the KTW (–0.67 ± 0.30 mm; F = 16.52; P = .003). Melsen and Allais9 compared the gingival situation of their patients before and after treatment with a fixed appliance and proinclination of mandibular incisors. They demonstrated that the increase in the prevalence of gingival recession during treatment was significant, but the increase in the mean gingival recession was not significant. Moreover, four variables were significantly related with the development or increase in the gingival recession during orthodontic treatment: baseline recession presence, KTW, periodontal biotype, and visual gingival inflammation.9 Although no statistical significance was observed, only one of the 16 subjects enrolled in that study who experienced the development of a gingival recession had a thin periodontal biotype and was orthodontically treated with proinclination of the mandibular incisors. KTW values in relation to the type of orthodontic movement were in agreement with those found by Andlin-Sobocki.29 When teeth were retroinclined, the KTW increased (0.46 ± 0.21 mm), whereas a loss of KTW was observed when the mandibular incisors were proinclined (–0.67 ± 0.30 mm).
A recent review failed to clarify the effect of orthodontic changes in incisor inclination on the occurrence of gingival recession.16 However, a strong and positive correlation was found between proinclination and thin biotype, both in terms of RD (R = 0.83; P = .001) and KTW (R = 0.87; P = 0.001).
Conclusions Within the limits of the present study, the periodontal biotype should be properly identified before orthodontic treatment to avoid the development of gingival recession. When gingival biotype is thin, all types of orthodontic movements seem to be unfavorable, leading to a loss of KTW and increasing the risk of gingival recession. Among the different types of movements, proinclination was always related to a loss of soft gingival tissue; the thinner the biotype, the higher the KTW loss. The use of the biotype probe is a reliable, friendly, and noninvasive way to classify the periodontal biotype.
Acknowledgment We are grateful to Hu-Friedy Company (Chicago, IL) for providing the biotype probes used in the study. Dr Giulio Rasperini did not participate in the data collection and data analysis, and does declare a financial interest with the biotype probe produced by Hu-Friedy. No other author declares any conflict of interest.
The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
675
References 1. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol 1999;4:1–6. 2. Löe H, Anerud A, Boysen H. The natural history of periodontal disease in man: Prevalence, severity, and extent of gingival recession. J Periodontol 1992; 63:489–495. 3. Khocht A, Simon G, Person P, Denepitiya JL. Gingival recession in relation to history of hard toothbrush use. J Periodontol 1993;64:900–905. 4. Sardella A, Pedrinazzi M, Bez C, Lodi G, Carrassi A. Labial piercing resulting in gingival recession. A case series. J Clin Periodontol 2002;29:961–963. 5. Levin L, Zadik Y, Becker T. Oral and dental complications of intraoral piercing. Dent Traumatol 2005;21:341–343. 6. Abboud M, Grüner M, Koeck B. Anterior crowding-just an esthetic problem? J Orofac Orthop 2002;63:264–273. 7. Trossello VK, Gianelly AA. Orthodontic treatment and periodontal status. J Periodontol 1979;50:665–671. 8. Renkema AM, Fudalej PS, Renkema AAP, Abbas F, Bronkhorst E, Katsaros C. Gingival labial recessions in orthodontically treated and untreated individuals: A pilot case–control study. J Clin Periodontol 2013;40:631–637. 9. Melsen B, Allais D. Factors of importance for the development of dehiscences during labial movement of mandibular incisors: A retrospective study of adult orthodontic patients. Am J Orthod Dentofacial Orthop 2005;127: 552–561. 10. Olsson M, Lindhe J. Periodontal characteristics in individuals with varying form of the upper central incisors. J Clin Periodontol 1991;18:78–82.
11. Baldi C, Pini-Prato G, Pagliaro U, et al. Coronally advanced flap procedure for root coverage. Is flap thickness a relevant predictor to achieve root coverage? A 19-case series. J Periodontol 1999;70: 1077–1784. 12. Cairo F, Pagliaro U, Nieri M. Treatment of gingival recession with coronally advanced flap procedures: A systematic review. J Clin Periodontol 2008;35(suppl 8): 136–162. 13. Kan JY, Rungcharassaeng K, Umezu K, Kois JC. Dimensions of peri-implant mucosa: An evaluation of maxillary anterior single implants in humans. J Periodontol 2003;74:557–562. 14. Aziz T, Flores-Mir C. A systematic review of the association between applianceinduced labial movement of mandibular incisors and gingival recession. Aust Orthod J 2011;27:33–39. 15. Vasconcelos G, Kjellsen K, Preus H, Vandevska-Radunovic V, Hansen BF. Prevalence and severity of vestibular recession in mandibular incisors after orthodontic treatment. Angle Orthod 2012; 82:42–47. 16. Joss-Vassalli I, Grebenstein C, Topouzelis N, Sculean A, Katsaros C. Orthodontic therapy and gingival recession: A systematic review. Orthod Craniofac Res 2010;13:127–141. 17. Ainamo J, Bay I. Problems and proposal for recording gingivitis and plaque. Int Dent J 1975;25:229–235. 18. O’Leary TJ, Drake RB, Naylor JE. The plaque control record. J Periodontol 1972;43:38. 19. Bollen AM, Cunha-Cruz J, Hujoel PP. Secular trends in preadult orthodontic care in the United States: 1942–2002. Am J Orthod Dentofacial Orthop 2007; 132:579–585.
20. Wedrychowska-Szulc B, Syrynska M. Patient and parent motivation for orthodontic treatment: A questionnaire study. Eur J Orthod 2010;32:447–452. 21. Khan M, Fida M. Assessment of psychosocial impact of dental aesthetics. J Coll Physicians Surg Pak 2008;18:559–564. 22. Reichert C, Hagner M, Jepsen S, Jäger A. Interfaces between orthodontic and periodontal treatment. J Orofac Orthop 2011;72:165–186. 23. Eghbali A, De Rouck T, De Bruyn H, Cosyn J. The gingival biotype assessed by experienced and inexperienced clinicians. J Clin Periodontol 2009;36: 958–963. 24. Greenberg J, Laster L, Listgarten MA. Transgingival probing as a potential estimator of alveolar bone level. J Periodontol 1976;47:514–517. 25. Müller HP, Heinecke A, Schaller N, Eger T. Masticatory mucosa in subjects with different periodontal phenotypes. J Clin Periodontol 2000;27:621–626. 26. Barriviera M, Duarte WR, Januário AL, Faber J, Bezerra AC. A new method to assess and measure palatal masticatory mucosa by cone-beam computerized tomography. J Clin Periodontol 2009; 36:564–568. 27. Fu JH, Yeh CY, Chan HL, Tatarakis N, Leong DJ, Wang HL. Tissue biotype and its relation to the underlying bone morphology. J Periodontol. 2010;81:569–574. 28. Dorfman HS. Mucogingival changes resulting from mandibular incisor tooth movement. Am J Orthod 1978;74: 286–297. 29. Andlin-Sobocki A. Changes of facial gingival dimensions in children: A 2-year longitudinal study. J Clin Periodontol 1993; 20:212–218.
Volume 35, Number 5, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
