Original Article
Alveolar bone changes after asymmetric rapid maxillary expansion Mehmet Akina; Zeliha Muge Bakaa; Zehra Ileria; Faruk Ayhan Basciftcib ABSTRACT Objective: To quantitatively evaluate the effects of asymmetric rapid maxillary expansion (ARME) on cortical bone thickness and buccal alveolar bone height (BABH), and to determine the formation of dehiscence and fenestration in the alveolar bone surrounding the posterior teeth, using conebeam computed tomography (CBCT). Materials and Methods: The CBCT records of 23 patients with true unilateral posterior skeletal crossbite (10 boys, 14.06 6 1.08 years old, and 13 girls, 13.64 6 1.32 years old) who had undergone ARME were selected from our clinic archives. The bonded acrylic ARME appliance, including an occlusal stopper, was used on all patients. CBCT records had been taken before ARME (T1) and after the 3-month retention period (T2). Axial slices of the CBCT images at 3 vertical levels were used to evaluate the buccal and palatal aspects of the canines, first and second premolars, and first molars. Paired samples and independent sample t-tests were used for statistical comparison. Results: The results suggest that buccal cortical bone thickness of the affected side was significantly more affected by the expansion than was the unaffected side (P , .05). ARME significantly reduced the BABH of the canines (P , .01) and the first and second premolars (P , .05) on the affected side. ARME also increased the incidence of dehiscence and fenestration on the affected side. Conclusions: ARME may quantitatively decrease buccal cortical bone thickness and height on the affected side. (Angle Orthod. 2015;85:799–805.) KEY WORDS: Asymmetric rapid maxillary expansion; Alveolar bone; Cone-beam computed tomography
patients, only the affected side should be expanded.1–3 If conventional bilateral rapid maxillary expansion (RME) is used in the true unilateral posterior crossbite, undesirable overexpansion and buccal nonocclusion occur on the unaffected side.4 To avoid these undesirable effects, Marshall et al.3 and Toroglu et al.4 recommended that the mandible be supported on the unaffected side. RME, in which heavy orthodontic force is transmitted to the maxilla through the teeth, is commonly used to correct maxillary posterior crossbite and constriction.5,6 Orthopedic expansion is achieved through RME not only by separating the midpalatal suture but also by the bending effect on dentoalveolar supporting tissues. These negative effects include buccal crown tipping, root resorption, decrease in alveolar bone thickness, and marginal bone loss.7,8 RME has also been reported to cause the loss of quality and amount of alveolar bone.9,10 Although the effects of RME on alveolar bone thickness and alveolar bone height have been investigated in previous studies using 3-D with cone-beam computed tomography (CBCT),9–11 to our knowledge no study evaluating the
INTRODUCTION Unilateral posterior crossbite is not an uncommon malocclusion in the orthodontic population. The reported prevalence of this malocclusion varies between 5.9% and 23%; functional cases dominate in different studies.1,2 Treatment of true unilateral posterior crossbite differs from treating functional unilateral or bilateral posterior crossbite. The aim in treating the functional unilateral and bilateral posterior crossbite should be expanding both sides. However, in true unilateral posterior crossbite a Assistant Professor, Department of Orthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey. b Professor, Department of Orthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey. Corresponding author: Dr Mehmet Akin, Selcuk Universitesi, Dishekimligi Faku¨ltesi Ortodonti AD, Selc¸uklu- 42079, Kampus, Konya, Turkey (e-mail: [email protected])
Accepted: October 2014. Submitted: September 2014. Published Online: December 5, 2014 G 2015 by The EH Angle Education and Research Foundation, Inc. DOI: 10.2319/090214.1
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effects of asymmetric rapid maxillary expansion (ARME) on alveolar bone in 3-D has been published. Therefore, the aim of this study was to evaluate the effects of ARME on alveolar bone thickness, buccal alveolar bone height (BABH), and the incidence of dehiscence and fenestration. MATERIALS AND METHODS This study was approved by the Ethical Committee on Research of the Faculty of Dentistry, Selcuk University. The CBCT records of 23 patients (10 boys, 14.06 6 1.08 years old, and 13 girls, 13.64 6 1.32 years old) who had undergone ARME were selected from the archives of the Orthodontic Department of Selcuk University in Konya, Turkey. Patients who participated in the study met the inclusion criteria shown in Table 1. All patients had been treated with modified acrylic bonded appliances, which were built by adding an occlusal-lock mechanism on the unaffected side (Figure 1). A hyrax screw (Dentaurum, Pforzheim, Germany) was placed in the acrylic plate parallel to the second premolars and as near to the palate as possible. This appliance was a type of splint-tooth–tissue-borne appliance. On the vestibular surfaces of the mandibular teeth, the acrylic part of the appliances extended over the occlusal and middle thirds of the teeth on the unaffected side. An acrylic part was formed that extended vertically from the palatal part of the maxillary posterior teeth to the lingual of the mandibular posterior teeth on the unaffected side. In this way, the mandibular posterior teeth acted as an acrylic lock mechanism on the unaffected side, avoiding expansion of the maxilla on this side. After occlusal adjustments were made, the appliance was cemented. In our department, the following protocol is used in maxillary expansion. Starting the day after cementation, the screw is turned twice a day (once each in the morning and evening) for the first week. After the palatal halves have been separated, the screw is turned once a day. The expansion process continues until the crossbite has been corrected and 2 mm–3 mm overexpansion obtained. During the retention period, the expansion appliance is left in the mouth for 3 months. All CBCT images were taken with a Kodak system (Model CS 9300; Carestream Health, Inc, Rochester, NY) at 8.0 mA and 70 kV for 6.15 seconds and with an
Figure 1. ARME expander appliances.
axial slice thickness of 0.18 mm. The patients were asked to place their head in the Frankfort horizontal position for the CBCT scans. The digital imaging and communications in medicine images were imported, and cross-sectional slices were made with Mimics software (version 14.01, Materialise, Leuven, Belgium). With this program, the 3-D image reconstructions were standardized by using the Frankfort horizontal plane (represented by a line on the image) as the x-axis, the transporionic plane as the y-axis, and the midsagittal plane as the z-axis. The reference plane was similar to that proposed by Baysal et al.11 and Sanders et al.12 Alveolar bone thickness and BABH were measured for each scan before ARME (T1) and after ARME (T2) by one investigator who was blinded to the patient time points.
Table 1. Inclusion Criteria 1 2 3 4 5
True unilateral posterior crossbite—not functional type—with coincident midlines related to a maxillary transverse deficiency, mandibular shift was performed clinically. In functional-type posterior crossbite, symmetrical expansion had been done. All maxillary permanent teeth erupted except the third molars. No previous orthodontic treatment or systemic disease. Skeletal Class I (ANB 5 0u–4u), normal overbite (1 mm–3 mm), normal growth direction (SN-GoGn 5 26u–38u). No amalgam filling or veneer crown. In 10 patients, the crossbite was on the left side; in 13, it was on the right side.
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Figure 4. Buccal alveolar bone height (BABH), distance between alveolar crest and cusp tip.
Figure 2. Measuring alveolar bone thickness levels.
The alveolar bone thickness of the maxillary canine, first and second premolars, and mesial and distal roots of the first molar for the affected and unaffected sides were measured using the axial clipping function of the software, measuring at 3 levels, the furcation, middle, and apical levels as proposed by Baysal et al.11 (Figure 2). These levels were measured in cross-section parallel to the Frankfort horizontal plane at the trifurcation, the middle, and the apex of the distobuccal root of the first molar tooth on the affected side, both buccally and palatally (Figure 3). The BABH was determined by measuring the distance between the cusp tips of the tooth and the buccal alveolar crest (Figure 4). Dehiscence and fenestration was evaluated using a method described by Evangelista.13 The total root length of each tooth was determined from axial and crosssectional images at the buccal and palatal surfaces. If the images showed no cortical bone around the root in at least three sequential views, the defects were recorded as dehiscence and fenestration (Figure 5). Statistical Analysis All statistical analyses were performed by using the Statistical Package for the Social Sciences (version
Figure 3. Buccal alveolar bone thickness and palatal alveolar bone thickness.
17.0; SPSS Inc, Chicago, Ill), and a P-value of , 0.05 was considered statistically significant. Four weeks after the first measurements, 15 randomly selected CBCT records were remeasured, and a paired samples t-test was applied to the measurements. The differences between the first and second measurements of the 15 CBCT records were insignificant. When intraclass correlation coefficients were performed to assess the reliability of the measurements as described by Houston14 in the same images, the coefficients of reliability for the measurements were shown to be above 0.921, indicating that the reliability of all measurements was acceptable. The Shapiro-Wilks normality test and Levene’s variance homogeneity were applied to the data. To compare the mean values of the affected and the unaffected side in T1 and T2 and the treatment effect, an independent sample t-test and a paired sample t-test, respectively, were used. RESULTS The descriptive statistical values and comparisons of the buccal alveolar bone thickness (BABT) measurements between the affected and the unaffected side and before and after ARME treatment are presented in Table 2. There were significant differences in the BABT of the furcation region of the canine, the first and second premolar, and the middle and the apical region of the first premolar between the affected and the unaffected side before treatment. After
Figure 5. The presence of fenestration. Angle Orthodontist, Vol 85, No 5, 2015
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Table 2. Buccal Alveolar Bone Thickness (BABT) Measurements and Statistical Comparison Between Affected and Unaffected Sides Before and After Treatmenta T1
Canine Furcation Middle Apical First premolar Furcation Middle Apical Second premolar Furcation Middle Apical First molar-mesial Furcation Middle Apical First molar-distal Furcation Middle Apical a
Treatment Comparison
N
Unaffected Affected Side Side Affected Side Side Side Mean 6 SD Mean 6 SD Comparison Mean 6 SD Mean 6 SD Comparison T1–T2
23 23 23
0.41 6 0.21 0.23 6 0.25 0.54 6 0.35 0.46 6 0.28 1.86 6 0.61 1.84 6 0.72
0.042 NS NS
0.16 6 0.22 0.18 6 0.28 0.40 6 0.56 0.44 6 0.39 1.72 6 0.90 1.77 6 0.82
NS NS NS
0.037* NS NS
NS NS NS
23 23 23
1.09 6 0.35 0.88 6 0.40 1.26 6 0.41 1.13 6 0.46 1.18 6 0.45 1.03 6 0.51
0.046 0.047 0.045
0.78 6 0.52 0.86 6 0.47 1.10 6 0.73 1.20 6 0.54 1.12 6 0.82 1.00 6 0.47
NS NS NS
0.041* NS NS
NS NS NS
23 23 23
1.98 6 0.55 1.7 6 0.61 2.32 6 0.58 2.29 6 0.60 2.06 6 0.62 2.11 6 0.58
0.039 NS NS
1.72 6 1.03 1.65 6 0.70 2.2 6 0.93 2.16 6 0.71 1.96 6 0.80 2.04 6 0.87
NS NS NS
NS NS NS
NS NS NS
23 23 23
1.34 6 0.57 1.26 6 0.49 2.02 6 0.70 2.10 6 0.75 2.21 6 0.84 2.30 6 0.97
NS NS NS
1.02 6 0.94 1.17 6 0.83 1.78 6 0.97 1.93 6 0.94 2.16 6 0.97 2.27 6 0.89
NS NS NS
0.033* 0.041* NS
NS NS NS
23 23 23
1.56 6 0.72 1.53 6 0.63 2.24 6 0.92 2.22 6 1.04 3.11 6 1.24 3.06 6 1.18
NS NS NS
1.21 6 0.85 1.39 6 0.67 2.20 6 1.05 2.13 6 0.97 3.00 6 1.36 2.97 6 1.08
NS NS NS
0.043* NS NS
NS NS NS
Affected Side Measurement Region
T2 Unaffected Side
Unaffected Side T1–T2
SD indicates standard deviation; T1, before treatment; T2, after retention; NS, not significant; * P , .05.
treatment, there were significant differences in the furcation region of the first premolar between the affected and unaffected sides. ARME did not significantly affect BABT on the unaffected side; however, the furcation regions of the canine, first and second premolar, mesial and distal segment of the molar, and middle region of the mesial segment of the molar were significantly affected. Descriptive statistical values and comparisons of the palatal alveolar bone thickness (PABT) between the affected and the unaffected side and before and after ARME treatment are presented in Table 3. There were no significant differences in PABT in the side comparison before treatment. However, there was a significant difference in the apical region of the canine: the PABT was decreased after treatment. The descriptive statistical values and comparisons of the BABH measurement between the affected and the unaffected side and before and after ARME treatment are presented in Table 4. The BABH increased significantly for the canine and both premolars on the affected side after treatment. The incidence and prevalence of alveolar defects (dehiscence and fenestration) on the affected and unaffected sides before and after ARME are presented in Table 5. In general, the prevalence of dehiscence was greater on the unaffected side than on the affected side in the same way the prevalence of Angle Orthodontist, Vol 85, No 5, 2015
fenestration was greater on the unaffected side than on the affected side in the first premolar buccal region. The percentage of dehiscence and fenestration increased after ARME treatment, especially on the affected side, and the buccal alveolar bone was also affected. DISCUSSION The characteristics of the unilateral posterior crossbite should be determined and separated from functional unilateral and bilateral posterior crossbite by careful diagnosis because the appliances and biomechanics used in treating a true unilateral posterior crossbite must differ from those of the bilateral posterior crossbite. RME is a common clinical procedure for correcting maxillary constriction,15 producing bilateral effects. However, clinicians want to produce only unilateral effects in treating true unilateral posterior crossbites. To obtain this unilateral expansion, several designs, modifications, and surgical procedures have been suggested.4,16,17 In this study, the ARME appliance was designed to strengthen the anchorage of the unaffected side by including, with the aid of an occlusal locking mechanism, the mandibular posterior teeth. Ekstro¨m et al., finding that bone mineralization of the midpalatal suture was completed at 3 months,
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Table 3. Palatal Alveolar Bone Thickness (PABT) Measurements and Statistical Comparison Between Affected and Unaffected Sides Before and After Treatmenta T1
Measurement Region Canine Furcation Middle Apical First premolar Furcation Middle Apical Second premolar Furcation Middle Apical First molar Furcation Middle Apical a
T2
Treatment Comparison
N
Unaffected Affected Side Side Affected Side Side Side Mean 6 SD Mean 6 SD Comparison Mean 6 SD Mean 6 SD Comparison T1-T2
23 23 23
2.16 6 0.74 2.24 6 0.83 2.33 6 0.82 2.41 6 0.97 4.19 6 1.19 4.08 6 1.30
NS NS NS
2.21 6 0.88 2.25 6 0.59 2.35 6 0.83 2.45 6 0.90 3.40 6 1.05 4.13 6 1.32
NS NS 0.038*
NS NS 0.041*
NS NS NS
23 23 23
1.12 6 0.64 1.17 6 0.73 1.62 6 0.90 1.58 6 0.82 3.26 6 2.02 3.35 6 1.87
NS NS NS
1.15 6 0.68 1.16 6 0.80 1.65 6 0.87 1.55 6 1.03 3.05 6 1.92 3.32 6 2.07
NS NS NS
NS NS NS
NS NS NS
23 23 23
1.69 6 0.67 1.63 6 0.81 2.00 6 0.78 2.08 6 0.83 4.15 6 1.67 4.22 6 1.31
NS NS NS
1.70 6 0.61 1.62 6 0.72 2.02 6 0.77 2.05 6 0.69 3.97 6 1.61 4.20 6 1.42
NS NS NS
NS NS NS
NS NS NS
23 23 23
1.51 6 0.61 1.45 6 0.70 1.61 6 0.54 1.57 6 0.47 2.32 6 0.92 2.17 6 1.05
NS NS NS
1.50 6 0.73 1.44 6 0.81 1.52 6 0.64 1.60 6 0.69 1.85 6 0.87 2.12 6 1.07
NS NS NS
NS NS 0.037*
NS NS NS
Affected Side
Unaffected Side
Unaffected Side T1–T2
SD indicates standard deviation; T1, before treatment; T2, after retention; NS, not significant; * P , .05.
recommended at least a 3-month retention period after RME for long-term stability.18 In our clinic, RME appliances are generally kept in the mouth for 3 months after RME. In addition, 3-month retention records were obtained from the clinic archive and used for our study. Therefore, this period was thought to be adequate for adaptation of the hard and soft tissues. The BABT of the furcation region of the canine, first and second premolar, and middle and apical region of the first premolar on the affected side was greater than on the unaffected side. After the ARME and retention period, these regions were almost balanced. The BABT of the affected side became thinner, especially the furcation region of the canine and first premolar, during the treatment period. PABT was not affected— as was BABT—by ARME; only the apical region of the canine and first molar were decreased. Hicks19 found that the molars on the affected side had greater palatal
inclination than did those on the unaffected side. Toroglu et al.4 found that the affected buccal teeth were more vertical than on the unaffected side, and during asymmetric maxillary expansion, the angulation of the posterior teeth was balanced on both sides in a true unilateral posterior crossbite malocclusion. The molars had greater tipping (7.3u) on the affected side than on the unaffected side (2.5u). Baysal et al.11 showed that RME had a detrimental effect on the BABT of both sides. These changes in the current study might be attributed to tipping of the maxillary posterior teeth, leading to resorption of the crestal, buccal, and palatal alveolar bone. Furcation measurement took place near the cervical region of the tooth and cervical edge of the alveolar bone crest; thus, the furcation region of the tooth was more directly influenced by tooth tipping than the normal position and reduced vertical alveolar bone height. Otherwise,
Table 4. Buccal Alveolar Bone Height (BABH) Measurements and Statistical Comparison Between Affected and Unaffected Sides Before and After Treatmenta
Measurement Region Canine First premolar Second premolar First molar Distobuccal Midfurcation Mesiobuccal a
T1
T2
Unaffected Affected Side Side
Unaffected Affected Side Side
Treatment Comparison Affected Side
Unaffected Side
N
Side Side Mean 6 SD Mean 6 SD Comparison Mean 6 SD Mean 6 SD Comparison
T1–T2
T1–T2
23 23 23
10.16 6 0.92 10.94 6 0.83 8.45 6 0.82 8.69 6 1.05 8.31 6 0.76 8.44 6 0.87
0.047 NS NS
11.96 6 1.07 11.21 6 1.07 10.09 6 0.92 9.02 6 1.12 9.75 6 0.81 8.78 6 1.00
0.044* 0.041* 0.038*
0.009** 0.011* 0.013*
NS NS NS
23 23 23
8.80 6 1.07 8.73 6 0.72 7.89 6 1.24 7.94 6 0.79 8.48 6 1.03 8.57 6 0.80
NS NS NS
9.91 6 1.13 9.02 6 1.15 8.14 6 0.97 8.04 6 1.08 9.72 6 0.88 8.78 6 1.07
0.045* NS 0.031*
0.017* NS 0.013*
NS NS NS
SD indicates standard deviation; T1, before treatment; T2, after retention; NS, not significant; * P , .05; ** P , .01. Angle Orthodontist, Vol 85, No 5, 2015
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Table 5. Incidence of Dehiscence and Fenestration Before and After Treatmenta Before Treatment Measurement Region Canine Labial Palatal First premolar Buccal Palatal Second premolar Buccal Palatal First molar Buccal Palatal a
Affected Side N
After Treatment
Unaffected Side
Affected Side
Unaffected Side
Dehiscence Fenestration Dehiscence Fenestration Dehiscence Fenestration Dehiscence Fenestration
23 23
5 (21.7) 2 (8.7)
1 (4.3) 0 (0.0)
9 (39.1) 0 (0.0)
1 (4.3) 0 (0.0)
14 (60.9) 3 (13.0)
2 (8.7) 0 (0.0)
10 (43.5) 0 (0.0)
1 (4.3) 0 (0.0)
23 23
1 (4.3) 1 (4.3)
3 (13.0) 0 (0.0)
2 (8.7) 0 (0.0)
7 (30.4) 0 (0.0)
11 (47.8) 0 (0.0)
5 (21.7) 0 (0.0)
3 (13.0) 0 (0.0)
7 (30.4) 0 (0.0)
23 23
0 (0.0) 0 (0.0)
0 (0.0) 0 (0.0)
1 (4.3) 0 (0.0)
0 (0.0) 0 (0.0)
2 (8.7) 2 (8.7)
1 (4.3) 0 (0.0)
2 (8.7) 1 (4.3)
0 (0.0) 0 (0.0)
23 23
0 (0.0) 2 (8.7)
4 (17.4) 1 (4.3)
2 (8.7) 1 (4.3)
4 (17.4) 0 (0.0)
9 (39.1) 3 (13.0)
5 (21.7) 1 (4.3)
4 (17.4) 2 (8.7)
5 (21.7) 1 (4.3)
Values are presented as number or number (%).
the apical region is located as far as the cervical region of the tooth; therefore, the apical region was associated with total transversal movement of the tooth. Brunetto et al.17 investigated changes in buccal alveolar bone after rapid and slow maxillary expansion, and found that both protocols caused vertical and horizontal bone loss and that BABH decreased during maxillary expansion. Baysal et al.11 found that banded RME caused decreases in the BABH on both sides. In the current ARME, the BABH of the canine and first and second premolars on the affected side decreased. This bone loss may be explained by crestal alveolar bone resorption during tooth tipping. However, there is significant disagreement about the means of analyzing RME reduction of vertical and horizontal bone. Variations might be attributed to methodologies, types of computerized tomography, device settings, and image voxels.11,18,19 Most studies showed that RME procedures reduce the amount of alveolar bone at different levels.20,21 Garib et al.10 found a 3.8-mm decrease in the BABH of the first molar and observed that tooth-borne RME appliances decreased bone levels more than did tooth-tissue–borne appliances. To our knowledge, no studies have been published about the buccal alveolar bone effects of asymmetric RME. Therefore, we tried to compare our results with those of RME. In the current study, the maximum BABH was observed in the canine (1.80 mm). This result was almost half what Garib et al.10 observed. We attribute this result to the our use of tooth-and-tissue–borne expansion appliances. Due to the considerable force needed to split the midpalatal suture during RME, patients suffer major periodontal problems such as dehiscence and fenestration.22 The signs of dehiscence increased from 4.3% to 47.8% on the buccal aspect of the first premolars and from 21.7% to 60.9% on the labial of the canines. Angle Orthodontist, Vol 85, No 5, 2015
In accordance with the current study, Baysal et al.11 found the incidence of dehiscence to be 55% after RME. Evangelista et al.13 found that maxillary canines and first premolars showed a high prevalence of dehiscence when they compared the presence of periodontal defects in different malocclusions. Our results showed that, at first the maxillary canine and first premolar suffered from periodontal consequences because of malocclusion and skeletal differences. We should not forget that CBCT cannot determine a thin bone segment clearly.23 However, these results cause suspicion. In the current study, CBCT images were used to evaluate the effects of ARME on alveolar bone. CBCT technology has many advantages compared with tomography, especially conventional radiographic imaging.17,24,25 Leung et al.26 showed that alveolar bone height and thickness can be measured quantitatively with great accuracy, with more than 0.870 correlations. Sun et al.23 observed that decreasing the voxel size from 0.40 mm to 0.25 mm could improve the accuracy of alveolar bone linear measurement from the CBCT images. Molen27 recommended that a voxel size less than 0.30 mm could provide better average spatial resolution for adequately visualizing alveolar bone. In the current study, the voxel size was set at 0.18 mm to obtain accurate alveolar bone linear measurement. Another factor that directly influences spatial resolution is metal artifacts.27 In the current study, the CBCT images were taken after the retention period when the ARME appliances had been removed and there were no amalgam restorations in the patients’ CBCT records. Further studies for evaluating the periodontal effects of ARME should be designed by comparing toothborne and tooth-and-tissue–borne appliances and including a control group. Another limitation of this
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study is the small sample size. The same author (M.A.) performed all measurements to overcome this limitation, and the high accuracy (a coefficient of more than 0.921) of the quantitative measurements supports the reliability of the results. CONCLUSIONS Within the limitations of this study, N ARME has detrimental effects on the supporting alveolar bone of the maxilla on the affected side. Alveolar bone height and thickness were decreased during the expansion and retention periods. N Dehiscence and fenestration were increased, especially on the maxillary canine and the first premolar of the affected side. REFERENCES 1. Kutin G, Hawes RR. Posterior cross-bites in the deciduous and mixed dentitions. Am J Orthod. 1969;56:491–504. 2. Proffit WR. Contemporary Orthodontics. 2nd ed. St Louis, Mo:Mosby; 1993. 3. Marshall SD, Southard KA, Southard TE. Early transverse treatment. Semin Orthod. 2005;11:130–119. 4. Toroglu MS, Uzel E, Kayalioglu M, Uzel I. Asymmetric maxillary expansion (AMEX) appliance for treatment of true unilateral posterior crossbite. Am J Orthod Dentofacial Orthop. 2002;122:164–173. 5. Langford SR, Sims MR. Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man. Am J Orthod. 1982;81:108–115. 6. Haas AJ. The treatment of maxillary deficiency by opening the mid-palatal suture. Angle Orthod. 1965;65:200–217. 7. Starnbach H, Bayne D, Cleall J, Subtelny JD. Facioskeletal and dental changes resulting from rapid maxillary expansion. Angle Orthod. 1966;36:152–164. 8. Odenrick L, Karlander EL, Pierce A, Kretschmar U. Surface resorption following two forms of rapid maxillary expansion. Eur J Orthod. 1991;13:264–270. 9. Kartalian A, Gohl E, Adamian M, Enciso R. Cone-beam computerized tomography evaluation of the maxillary dentoskeletal complex after rapid palatal expansion. Am J Orthod Dentofacial Orthop. 2010;138:486–492. 10. Garib DG, Henriques JF, Janson G, Freitas MR, Coelho RA. Rapid maxillary expansion—tooth tissue-borne versus tooth-borne expanders: a computed tomography evaluation of dentoskeletal effects. Angle Orthod. 2005;75:548–557. 11. Baysal A, Uysal T, Veli I, Ozer T, Karadede I, Hekimoglu S. Evaluation of alveolar bone loss following rapid maxillary expansion using cone-beam computed tomography. Korean J Orthod. 2013;43:83–95. 12. Sanders DA, Rigali PH, Neace WP, Uribe F, Nanda R. Skeletal and dental asymmetries in Class II subdivision
13.
14. 15.
16.
17.
18.
19.
20.
21.
22.
23.
24. 25.
26.
27.
malocclusions using cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2010;138:542.e1–e20. Evangelista K, Vasconcelos Kde F, Bumann A, Hirsch E, Nitka M, Silva MA. Dehiscence and fenestration in patients with Class I and Class II division 1 malocclusion assessed with cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2010;138:133.e1–e7. Houston WJB. The analysis of errors in orthodontic measurements. Am J Orthod. 1983;83:382–390. Krebs A. Midpalatal suture expansion studies by the implant method over a seven-year period. Rep Congr Eur Orthod Soc. 1964;40:131–142. Hassan AH, AlGhamdi AT, Al-Fraidi AA, Al-Hubail A, Hajrassy MK. Unilateral cross bite treated by corticotomyassisted expansion: two case reports. Head Face Med. 2010;19:6. Brunetto M, Andriani Jda S, Ribeiro GL, Locks A, Correa M, Correa LR. Three-dimensional assessment of buccal alveolar bone after rapid and slow maxillary expansion: a clinical trial study. Am J Orthod Dentofacial Orthop. 2013 May;143:633–644. Ekstro¨m C, Henrikson CO, Jensen R. Mineralization in the midpalatal suture after orthodontic expansion. Am J Orthod. 1977;71:449–455. Hicks EP. Slow maxillary expansion: a clinical study of the skeletal versus dental response to low magnitude force. Am J Orthod. 1978;73:121–141. Ballanti F, Lione R, Fanucci E, Franchi L, Baccetti T, Cozza P. Immediate and post-retention effects of rapid maxillary expansion investigated by computed tomography in growing patients. Angle Orthod. 2009;79:24–29. Gauthier C, Voyer R, Paquette M, Rompree P, Papadakis A. Periodontal effects of surgically assisted rapid palatal expansion evaluated clinically and with cone-beam computerized tomography: 6-month preliminary results. Am J Orthod Dentofacial Orthop. 2011;139:117–128. Akkaya S, Lorenzon S, Ucem TT. A comparison of sagittal and vertical effects between bonded rapid and slow maxillary expansion procedures. Eur J Orthod. 1999;21: 175–180. Sun Z, Smith T, Kortam S, Kim DG, Tee BC, Fields H. Effect of bone thickness on alveolar bone-height measurements from cone-beam computed tomography images. Am J Orthod Dentofacial Orthop. 2011 Feb;139:e117–e127. Hatcher DC, Aboudara CL. Diagnosis goes digital. Am J Orthod Dentofacial Orthop. 2004;125:512–515. Ribeiro G, Locks A, Pereira J, Brunetto M. Analysis of rapid maxillary expansion using cone-beam computed tomography. Dent Press J Orthod. 2010;15:107–112. Leung CC, Palomo L, Griffith R, Hans MG. Accuracy and reliability of cone-beam computed tomography for measuring alveolar bone height and detecting bony dehiscences and fenestrations. Am J Orthod Dentofacial Orthop. 2010; 137:109–119. Molen AD. Considerations in the use of cone-beam computed tomography for buccal bone measurements. Am J Orthod Dentofacial Orthop. 2010;137:130–135.
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Alveolar bone changes after asymmetric rapid maxillary expansion Mehmet Akina; Zeliha Muge Bakaa; Zehra Ileria; Faruk Ayhan Basciftcib ABSTRACT Objective: To quantitatively evaluate the effects of asymmetric rapid maxillary expansion (ARME) on cortical bone thickness and buccal alveolar bone height (BABH), and to determine the formation of dehiscence and fenestration in the alveolar bone surrounding the posterior teeth, using conebeam computed tomography (CBCT). Materials and Methods: The CBCT records of 23 patients with true unilateral posterior skeletal crossbite (10 boys, 14.06 6 1.08 years old, and 13 girls, 13.64 6 1.32 years old) who had undergone ARME were selected from our clinic archives. The bonded acrylic ARME appliance, including an occlusal stopper, was used on all patients. CBCT records had been taken before ARME (T1) and after the 3-month retention period (T2). Axial slices of the CBCT images at 3 vertical levels were used to evaluate the buccal and palatal aspects of the canines, first and second premolars, and first molars. Paired samples and independent sample t-tests were used for statistical comparison. Results: The results suggest that buccal cortical bone thickness of the affected side was significantly more affected by the expansion than was the unaffected side (P , .05). ARME significantly reduced the BABH of the canines (P , .01) and the first and second premolars (P , .05) on the affected side. ARME also increased the incidence of dehiscence and fenestration on the affected side. Conclusions: ARME may quantitatively decrease buccal cortical bone thickness and height on the affected side. (Angle Orthod. 2015;85:799–805.) KEY WORDS: Asymmetric rapid maxillary expansion; Alveolar bone; Cone-beam computed tomography
patients, only the affected side should be expanded.1–3 If conventional bilateral rapid maxillary expansion (RME) is used in the true unilateral posterior crossbite, undesirable overexpansion and buccal nonocclusion occur on the unaffected side.4 To avoid these undesirable effects, Marshall et al.3 and Toroglu et al.4 recommended that the mandible be supported on the unaffected side. RME, in which heavy orthodontic force is transmitted to the maxilla through the teeth, is commonly used to correct maxillary posterior crossbite and constriction.5,6 Orthopedic expansion is achieved through RME not only by separating the midpalatal suture but also by the bending effect on dentoalveolar supporting tissues. These negative effects include buccal crown tipping, root resorption, decrease in alveolar bone thickness, and marginal bone loss.7,8 RME has also been reported to cause the loss of quality and amount of alveolar bone.9,10 Although the effects of RME on alveolar bone thickness and alveolar bone height have been investigated in previous studies using 3-D with cone-beam computed tomography (CBCT),9–11 to our knowledge no study evaluating the
INTRODUCTION Unilateral posterior crossbite is not an uncommon malocclusion in the orthodontic population. The reported prevalence of this malocclusion varies between 5.9% and 23%; functional cases dominate in different studies.1,2 Treatment of true unilateral posterior crossbite differs from treating functional unilateral or bilateral posterior crossbite. The aim in treating the functional unilateral and bilateral posterior crossbite should be expanding both sides. However, in true unilateral posterior crossbite a Assistant Professor, Department of Orthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey. b Professor, Department of Orthodontics, Faculty of Dentistry, Selcuk University, Konya, Turkey. Corresponding author: Dr Mehmet Akin, Selcuk Universitesi, Dishekimligi Faku¨ltesi Ortodonti AD, Selc¸uklu- 42079, Kampus, Konya, Turkey (e-mail: [email protected])
Accepted: October 2014. Submitted: September 2014. Published Online: December 5, 2014 G 2015 by The EH Angle Education and Research Foundation, Inc. DOI: 10.2319/090214.1
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effects of asymmetric rapid maxillary expansion (ARME) on alveolar bone in 3-D has been published. Therefore, the aim of this study was to evaluate the effects of ARME on alveolar bone thickness, buccal alveolar bone height (BABH), and the incidence of dehiscence and fenestration. MATERIALS AND METHODS This study was approved by the Ethical Committee on Research of the Faculty of Dentistry, Selcuk University. The CBCT records of 23 patients (10 boys, 14.06 6 1.08 years old, and 13 girls, 13.64 6 1.32 years old) who had undergone ARME were selected from the archives of the Orthodontic Department of Selcuk University in Konya, Turkey. Patients who participated in the study met the inclusion criteria shown in Table 1. All patients had been treated with modified acrylic bonded appliances, which were built by adding an occlusal-lock mechanism on the unaffected side (Figure 1). A hyrax screw (Dentaurum, Pforzheim, Germany) was placed in the acrylic plate parallel to the second premolars and as near to the palate as possible. This appliance was a type of splint-tooth–tissue-borne appliance. On the vestibular surfaces of the mandibular teeth, the acrylic part of the appliances extended over the occlusal and middle thirds of the teeth on the unaffected side. An acrylic part was formed that extended vertically from the palatal part of the maxillary posterior teeth to the lingual of the mandibular posterior teeth on the unaffected side. In this way, the mandibular posterior teeth acted as an acrylic lock mechanism on the unaffected side, avoiding expansion of the maxilla on this side. After occlusal adjustments were made, the appliance was cemented. In our department, the following protocol is used in maxillary expansion. Starting the day after cementation, the screw is turned twice a day (once each in the morning and evening) for the first week. After the palatal halves have been separated, the screw is turned once a day. The expansion process continues until the crossbite has been corrected and 2 mm–3 mm overexpansion obtained. During the retention period, the expansion appliance is left in the mouth for 3 months. All CBCT images were taken with a Kodak system (Model CS 9300; Carestream Health, Inc, Rochester, NY) at 8.0 mA and 70 kV for 6.15 seconds and with an
Figure 1. ARME expander appliances.
axial slice thickness of 0.18 mm. The patients were asked to place their head in the Frankfort horizontal position for the CBCT scans. The digital imaging and communications in medicine images were imported, and cross-sectional slices were made with Mimics software (version 14.01, Materialise, Leuven, Belgium). With this program, the 3-D image reconstructions were standardized by using the Frankfort horizontal plane (represented by a line on the image) as the x-axis, the transporionic plane as the y-axis, and the midsagittal plane as the z-axis. The reference plane was similar to that proposed by Baysal et al.11 and Sanders et al.12 Alveolar bone thickness and BABH were measured for each scan before ARME (T1) and after ARME (T2) by one investigator who was blinded to the patient time points.
Table 1. Inclusion Criteria 1 2 3 4 5
True unilateral posterior crossbite—not functional type—with coincident midlines related to a maxillary transverse deficiency, mandibular shift was performed clinically. In functional-type posterior crossbite, symmetrical expansion had been done. All maxillary permanent teeth erupted except the third molars. No previous orthodontic treatment or systemic disease. Skeletal Class I (ANB 5 0u–4u), normal overbite (1 mm–3 mm), normal growth direction (SN-GoGn 5 26u–38u). No amalgam filling or veneer crown. In 10 patients, the crossbite was on the left side; in 13, it was on the right side.
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Figure 4. Buccal alveolar bone height (BABH), distance between alveolar crest and cusp tip.
Figure 2. Measuring alveolar bone thickness levels.
The alveolar bone thickness of the maxillary canine, first and second premolars, and mesial and distal roots of the first molar for the affected and unaffected sides were measured using the axial clipping function of the software, measuring at 3 levels, the furcation, middle, and apical levels as proposed by Baysal et al.11 (Figure 2). These levels were measured in cross-section parallel to the Frankfort horizontal plane at the trifurcation, the middle, and the apex of the distobuccal root of the first molar tooth on the affected side, both buccally and palatally (Figure 3). The BABH was determined by measuring the distance between the cusp tips of the tooth and the buccal alveolar crest (Figure 4). Dehiscence and fenestration was evaluated using a method described by Evangelista.13 The total root length of each tooth was determined from axial and crosssectional images at the buccal and palatal surfaces. If the images showed no cortical bone around the root in at least three sequential views, the defects were recorded as dehiscence and fenestration (Figure 5). Statistical Analysis All statistical analyses were performed by using the Statistical Package for the Social Sciences (version
Figure 3. Buccal alveolar bone thickness and palatal alveolar bone thickness.
17.0; SPSS Inc, Chicago, Ill), and a P-value of , 0.05 was considered statistically significant. Four weeks after the first measurements, 15 randomly selected CBCT records were remeasured, and a paired samples t-test was applied to the measurements. The differences between the first and second measurements of the 15 CBCT records were insignificant. When intraclass correlation coefficients were performed to assess the reliability of the measurements as described by Houston14 in the same images, the coefficients of reliability for the measurements were shown to be above 0.921, indicating that the reliability of all measurements was acceptable. The Shapiro-Wilks normality test and Levene’s variance homogeneity were applied to the data. To compare the mean values of the affected and the unaffected side in T1 and T2 and the treatment effect, an independent sample t-test and a paired sample t-test, respectively, were used. RESULTS The descriptive statistical values and comparisons of the buccal alveolar bone thickness (BABT) measurements between the affected and the unaffected side and before and after ARME treatment are presented in Table 2. There were significant differences in the BABT of the furcation region of the canine, the first and second premolar, and the middle and the apical region of the first premolar between the affected and the unaffected side before treatment. After
Figure 5. The presence of fenestration. Angle Orthodontist, Vol 85, No 5, 2015
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Table 2. Buccal Alveolar Bone Thickness (BABT) Measurements and Statistical Comparison Between Affected and Unaffected Sides Before and After Treatmenta T1
Canine Furcation Middle Apical First premolar Furcation Middle Apical Second premolar Furcation Middle Apical First molar-mesial Furcation Middle Apical First molar-distal Furcation Middle Apical a
Treatment Comparison
N
Unaffected Affected Side Side Affected Side Side Side Mean 6 SD Mean 6 SD Comparison Mean 6 SD Mean 6 SD Comparison T1–T2
23 23 23
0.41 6 0.21 0.23 6 0.25 0.54 6 0.35 0.46 6 0.28 1.86 6 0.61 1.84 6 0.72
0.042 NS NS
0.16 6 0.22 0.18 6 0.28 0.40 6 0.56 0.44 6 0.39 1.72 6 0.90 1.77 6 0.82
NS NS NS
0.037* NS NS
NS NS NS
23 23 23
1.09 6 0.35 0.88 6 0.40 1.26 6 0.41 1.13 6 0.46 1.18 6 0.45 1.03 6 0.51
0.046 0.047 0.045
0.78 6 0.52 0.86 6 0.47 1.10 6 0.73 1.20 6 0.54 1.12 6 0.82 1.00 6 0.47
NS NS NS
0.041* NS NS
NS NS NS
23 23 23
1.98 6 0.55 1.7 6 0.61 2.32 6 0.58 2.29 6 0.60 2.06 6 0.62 2.11 6 0.58
0.039 NS NS
1.72 6 1.03 1.65 6 0.70 2.2 6 0.93 2.16 6 0.71 1.96 6 0.80 2.04 6 0.87
NS NS NS
NS NS NS
NS NS NS
23 23 23
1.34 6 0.57 1.26 6 0.49 2.02 6 0.70 2.10 6 0.75 2.21 6 0.84 2.30 6 0.97
NS NS NS
1.02 6 0.94 1.17 6 0.83 1.78 6 0.97 1.93 6 0.94 2.16 6 0.97 2.27 6 0.89
NS NS NS
0.033* 0.041* NS
NS NS NS
23 23 23
1.56 6 0.72 1.53 6 0.63 2.24 6 0.92 2.22 6 1.04 3.11 6 1.24 3.06 6 1.18
NS NS NS
1.21 6 0.85 1.39 6 0.67 2.20 6 1.05 2.13 6 0.97 3.00 6 1.36 2.97 6 1.08
NS NS NS
0.043* NS NS
NS NS NS
Affected Side Measurement Region
T2 Unaffected Side
Unaffected Side T1–T2
SD indicates standard deviation; T1, before treatment; T2, after retention; NS, not significant; * P , .05.
treatment, there were significant differences in the furcation region of the first premolar between the affected and unaffected sides. ARME did not significantly affect BABT on the unaffected side; however, the furcation regions of the canine, first and second premolar, mesial and distal segment of the molar, and middle region of the mesial segment of the molar were significantly affected. Descriptive statistical values and comparisons of the palatal alveolar bone thickness (PABT) between the affected and the unaffected side and before and after ARME treatment are presented in Table 3. There were no significant differences in PABT in the side comparison before treatment. However, there was a significant difference in the apical region of the canine: the PABT was decreased after treatment. The descriptive statistical values and comparisons of the BABH measurement between the affected and the unaffected side and before and after ARME treatment are presented in Table 4. The BABH increased significantly for the canine and both premolars on the affected side after treatment. The incidence and prevalence of alveolar defects (dehiscence and fenestration) on the affected and unaffected sides before and after ARME are presented in Table 5. In general, the prevalence of dehiscence was greater on the unaffected side than on the affected side in the same way the prevalence of Angle Orthodontist, Vol 85, No 5, 2015
fenestration was greater on the unaffected side than on the affected side in the first premolar buccal region. The percentage of dehiscence and fenestration increased after ARME treatment, especially on the affected side, and the buccal alveolar bone was also affected. DISCUSSION The characteristics of the unilateral posterior crossbite should be determined and separated from functional unilateral and bilateral posterior crossbite by careful diagnosis because the appliances and biomechanics used in treating a true unilateral posterior crossbite must differ from those of the bilateral posterior crossbite. RME is a common clinical procedure for correcting maxillary constriction,15 producing bilateral effects. However, clinicians want to produce only unilateral effects in treating true unilateral posterior crossbites. To obtain this unilateral expansion, several designs, modifications, and surgical procedures have been suggested.4,16,17 In this study, the ARME appliance was designed to strengthen the anchorage of the unaffected side by including, with the aid of an occlusal locking mechanism, the mandibular posterior teeth. Ekstro¨m et al., finding that bone mineralization of the midpalatal suture was completed at 3 months,
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Table 3. Palatal Alveolar Bone Thickness (PABT) Measurements and Statistical Comparison Between Affected and Unaffected Sides Before and After Treatmenta T1
Measurement Region Canine Furcation Middle Apical First premolar Furcation Middle Apical Second premolar Furcation Middle Apical First molar Furcation Middle Apical a
T2
Treatment Comparison
N
Unaffected Affected Side Side Affected Side Side Side Mean 6 SD Mean 6 SD Comparison Mean 6 SD Mean 6 SD Comparison T1-T2
23 23 23
2.16 6 0.74 2.24 6 0.83 2.33 6 0.82 2.41 6 0.97 4.19 6 1.19 4.08 6 1.30
NS NS NS
2.21 6 0.88 2.25 6 0.59 2.35 6 0.83 2.45 6 0.90 3.40 6 1.05 4.13 6 1.32
NS NS 0.038*
NS NS 0.041*
NS NS NS
23 23 23
1.12 6 0.64 1.17 6 0.73 1.62 6 0.90 1.58 6 0.82 3.26 6 2.02 3.35 6 1.87
NS NS NS
1.15 6 0.68 1.16 6 0.80 1.65 6 0.87 1.55 6 1.03 3.05 6 1.92 3.32 6 2.07
NS NS NS
NS NS NS
NS NS NS
23 23 23
1.69 6 0.67 1.63 6 0.81 2.00 6 0.78 2.08 6 0.83 4.15 6 1.67 4.22 6 1.31
NS NS NS
1.70 6 0.61 1.62 6 0.72 2.02 6 0.77 2.05 6 0.69 3.97 6 1.61 4.20 6 1.42
NS NS NS
NS NS NS
NS NS NS
23 23 23
1.51 6 0.61 1.45 6 0.70 1.61 6 0.54 1.57 6 0.47 2.32 6 0.92 2.17 6 1.05
NS NS NS
1.50 6 0.73 1.44 6 0.81 1.52 6 0.64 1.60 6 0.69 1.85 6 0.87 2.12 6 1.07
NS NS NS
NS NS 0.037*
NS NS NS
Affected Side
Unaffected Side
Unaffected Side T1–T2
SD indicates standard deviation; T1, before treatment; T2, after retention; NS, not significant; * P , .05.
recommended at least a 3-month retention period after RME for long-term stability.18 In our clinic, RME appliances are generally kept in the mouth for 3 months after RME. In addition, 3-month retention records were obtained from the clinic archive and used for our study. Therefore, this period was thought to be adequate for adaptation of the hard and soft tissues. The BABT of the furcation region of the canine, first and second premolar, and middle and apical region of the first premolar on the affected side was greater than on the unaffected side. After the ARME and retention period, these regions were almost balanced. The BABT of the affected side became thinner, especially the furcation region of the canine and first premolar, during the treatment period. PABT was not affected— as was BABT—by ARME; only the apical region of the canine and first molar were decreased. Hicks19 found that the molars on the affected side had greater palatal
inclination than did those on the unaffected side. Toroglu et al.4 found that the affected buccal teeth were more vertical than on the unaffected side, and during asymmetric maxillary expansion, the angulation of the posterior teeth was balanced on both sides in a true unilateral posterior crossbite malocclusion. The molars had greater tipping (7.3u) on the affected side than on the unaffected side (2.5u). Baysal et al.11 showed that RME had a detrimental effect on the BABT of both sides. These changes in the current study might be attributed to tipping of the maxillary posterior teeth, leading to resorption of the crestal, buccal, and palatal alveolar bone. Furcation measurement took place near the cervical region of the tooth and cervical edge of the alveolar bone crest; thus, the furcation region of the tooth was more directly influenced by tooth tipping than the normal position and reduced vertical alveolar bone height. Otherwise,
Table 4. Buccal Alveolar Bone Height (BABH) Measurements and Statistical Comparison Between Affected and Unaffected Sides Before and After Treatmenta
Measurement Region Canine First premolar Second premolar First molar Distobuccal Midfurcation Mesiobuccal a
T1
T2
Unaffected Affected Side Side
Unaffected Affected Side Side
Treatment Comparison Affected Side
Unaffected Side
N
Side Side Mean 6 SD Mean 6 SD Comparison Mean 6 SD Mean 6 SD Comparison
T1–T2
T1–T2
23 23 23
10.16 6 0.92 10.94 6 0.83 8.45 6 0.82 8.69 6 1.05 8.31 6 0.76 8.44 6 0.87
0.047 NS NS
11.96 6 1.07 11.21 6 1.07 10.09 6 0.92 9.02 6 1.12 9.75 6 0.81 8.78 6 1.00
0.044* 0.041* 0.038*
0.009** 0.011* 0.013*
NS NS NS
23 23 23
8.80 6 1.07 8.73 6 0.72 7.89 6 1.24 7.94 6 0.79 8.48 6 1.03 8.57 6 0.80
NS NS NS
9.91 6 1.13 9.02 6 1.15 8.14 6 0.97 8.04 6 1.08 9.72 6 0.88 8.78 6 1.07
0.045* NS 0.031*
0.017* NS 0.013*
NS NS NS
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Table 5. Incidence of Dehiscence and Fenestration Before and After Treatmenta Before Treatment Measurement Region Canine Labial Palatal First premolar Buccal Palatal Second premolar Buccal Palatal First molar Buccal Palatal a
Affected Side N
After Treatment
Unaffected Side
Affected Side
Unaffected Side
Dehiscence Fenestration Dehiscence Fenestration Dehiscence Fenestration Dehiscence Fenestration
23 23
5 (21.7) 2 (8.7)
1 (4.3) 0 (0.0)
9 (39.1) 0 (0.0)
1 (4.3) 0 (0.0)
14 (60.9) 3 (13.0)
2 (8.7) 0 (0.0)
10 (43.5) 0 (0.0)
1 (4.3) 0 (0.0)
23 23
1 (4.3) 1 (4.3)
3 (13.0) 0 (0.0)
2 (8.7) 0 (0.0)
7 (30.4) 0 (0.0)
11 (47.8) 0 (0.0)
5 (21.7) 0 (0.0)
3 (13.0) 0 (0.0)
7 (30.4) 0 (0.0)
23 23
0 (0.0) 0 (0.0)
0 (0.0) 0 (0.0)
1 (4.3) 0 (0.0)
0 (0.0) 0 (0.0)
2 (8.7) 2 (8.7)
1 (4.3) 0 (0.0)
2 (8.7) 1 (4.3)
0 (0.0) 0 (0.0)
23 23
0 (0.0) 2 (8.7)
4 (17.4) 1 (4.3)
2 (8.7) 1 (4.3)
4 (17.4) 0 (0.0)
9 (39.1) 3 (13.0)
5 (21.7) 1 (4.3)
4 (17.4) 2 (8.7)
5 (21.7) 1 (4.3)
Values are presented as number or number (%).
the apical region is located as far as the cervical region of the tooth; therefore, the apical region was associated with total transversal movement of the tooth. Brunetto et al.17 investigated changes in buccal alveolar bone after rapid and slow maxillary expansion, and found that both protocols caused vertical and horizontal bone loss and that BABH decreased during maxillary expansion. Baysal et al.11 found that banded RME caused decreases in the BABH on both sides. In the current ARME, the BABH of the canine and first and second premolars on the affected side decreased. This bone loss may be explained by crestal alveolar bone resorption during tooth tipping. However, there is significant disagreement about the means of analyzing RME reduction of vertical and horizontal bone. Variations might be attributed to methodologies, types of computerized tomography, device settings, and image voxels.11,18,19 Most studies showed that RME procedures reduce the amount of alveolar bone at different levels.20,21 Garib et al.10 found a 3.8-mm decrease in the BABH of the first molar and observed that tooth-borne RME appliances decreased bone levels more than did tooth-tissue–borne appliances. To our knowledge, no studies have been published about the buccal alveolar bone effects of asymmetric RME. Therefore, we tried to compare our results with those of RME. In the current study, the maximum BABH was observed in the canine (1.80 mm). This result was almost half what Garib et al.10 observed. We attribute this result to the our use of tooth-and-tissue–borne expansion appliances. Due to the considerable force needed to split the midpalatal suture during RME, patients suffer major periodontal problems such as dehiscence and fenestration.22 The signs of dehiscence increased from 4.3% to 47.8% on the buccal aspect of the first premolars and from 21.7% to 60.9% on the labial of the canines. Angle Orthodontist, Vol 85, No 5, 2015
In accordance with the current study, Baysal et al.11 found the incidence of dehiscence to be 55% after RME. Evangelista et al.13 found that maxillary canines and first premolars showed a high prevalence of dehiscence when they compared the presence of periodontal defects in different malocclusions. Our results showed that, at first the maxillary canine and first premolar suffered from periodontal consequences because of malocclusion and skeletal differences. We should not forget that CBCT cannot determine a thin bone segment clearly.23 However, these results cause suspicion. In the current study, CBCT images were used to evaluate the effects of ARME on alveolar bone. CBCT technology has many advantages compared with tomography, especially conventional radiographic imaging.17,24,25 Leung et al.26 showed that alveolar bone height and thickness can be measured quantitatively with great accuracy, with more than 0.870 correlations. Sun et al.23 observed that decreasing the voxel size from 0.40 mm to 0.25 mm could improve the accuracy of alveolar bone linear measurement from the CBCT images. Molen27 recommended that a voxel size less than 0.30 mm could provide better average spatial resolution for adequately visualizing alveolar bone. In the current study, the voxel size was set at 0.18 mm to obtain accurate alveolar bone linear measurement. Another factor that directly influences spatial resolution is metal artifacts.27 In the current study, the CBCT images were taken after the retention period when the ARME appliances had been removed and there were no amalgam restorations in the patients’ CBCT records. Further studies for evaluating the periodontal effects of ARME should be designed by comparing toothborne and tooth-and-tissue–borne appliances and including a control group. Another limitation of this
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study is the small sample size. The same author (M.A.) performed all measurements to overcome this limitation, and the high accuracy (a coefficient of more than 0.921) of the quantitative measurements supports the reliability of the results. CONCLUSIONS Within the limitations of this study, N ARME has detrimental effects on the supporting alveolar bone of the maxilla on the affected side. Alveolar bone height and thickness were decreased during the expansion and retention periods. N Dehiscence and fenestration were increased, especially on the maxillary canine and the first premolar of the affected side. REFERENCES 1. Kutin G, Hawes RR. Posterior cross-bites in the deciduous and mixed dentitions. Am J Orthod. 1969;56:491–504. 2. Proffit WR. Contemporary Orthodontics. 2nd ed. St Louis, Mo:Mosby; 1993. 3. Marshall SD, Southard KA, Southard TE. Early transverse treatment. Semin Orthod. 2005;11:130–119. 4. Toroglu MS, Uzel E, Kayalioglu M, Uzel I. Asymmetric maxillary expansion (AMEX) appliance for treatment of true unilateral posterior crossbite. Am J Orthod Dentofacial Orthop. 2002;122:164–173. 5. Langford SR, Sims MR. Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man. Am J Orthod. 1982;81:108–115. 6. Haas AJ. The treatment of maxillary deficiency by opening the mid-palatal suture. Angle Orthod. 1965;65:200–217. 7. Starnbach H, Bayne D, Cleall J, Subtelny JD. Facioskeletal and dental changes resulting from rapid maxillary expansion. Angle Orthod. 1966;36:152–164. 8. Odenrick L, Karlander EL, Pierce A, Kretschmar U. Surface resorption following two forms of rapid maxillary expansion. Eur J Orthod. 1991;13:264–270. 9. Kartalian A, Gohl E, Adamian M, Enciso R. Cone-beam computerized tomography evaluation of the maxillary dentoskeletal complex after rapid palatal expansion. Am J Orthod Dentofacial Orthop. 2010;138:486–492. 10. Garib DG, Henriques JF, Janson G, Freitas MR, Coelho RA. Rapid maxillary expansion—tooth tissue-borne versus tooth-borne expanders: a computed tomography evaluation of dentoskeletal effects. Angle Orthod. 2005;75:548–557. 11. Baysal A, Uysal T, Veli I, Ozer T, Karadede I, Hekimoglu S. Evaluation of alveolar bone loss following rapid maxillary expansion using cone-beam computed tomography. Korean J Orthod. 2013;43:83–95. 12. Sanders DA, Rigali PH, Neace WP, Uribe F, Nanda R. Skeletal and dental asymmetries in Class II subdivision
13.
14. 15.
16.
17.
18.
19.
20.
21.
22.
23.
24. 25.
26.
27.
malocclusions using cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2010;138:542.e1–e20. Evangelista K, Vasconcelos Kde F, Bumann A, Hirsch E, Nitka M, Silva MA. Dehiscence and fenestration in patients with Class I and Class II division 1 malocclusion assessed with cone-beam computed tomography. Am J Orthod Dentofacial Orthop. 2010;138:133.e1–e7. Houston WJB. The analysis of errors in orthodontic measurements. Am J Orthod. 1983;83:382–390. Krebs A. Midpalatal suture expansion studies by the implant method over a seven-year period. Rep Congr Eur Orthod Soc. 1964;40:131–142. Hassan AH, AlGhamdi AT, Al-Fraidi AA, Al-Hubail A, Hajrassy MK. Unilateral cross bite treated by corticotomyassisted expansion: two case reports. Head Face Med. 2010;19:6. Brunetto M, Andriani Jda S, Ribeiro GL, Locks A, Correa M, Correa LR. Three-dimensional assessment of buccal alveolar bone after rapid and slow maxillary expansion: a clinical trial study. Am J Orthod Dentofacial Orthop. 2013 May;143:633–644. Ekstro¨m C, Henrikson CO, Jensen R. Mineralization in the midpalatal suture after orthodontic expansion. Am J Orthod. 1977;71:449–455. Hicks EP. Slow maxillary expansion: a clinical study of the skeletal versus dental response to low magnitude force. Am J Orthod. 1978;73:121–141. Ballanti F, Lione R, Fanucci E, Franchi L, Baccetti T, Cozza P. Immediate and post-retention effects of rapid maxillary expansion investigated by computed tomography in growing patients. Angle Orthod. 2009;79:24–29. Gauthier C, Voyer R, Paquette M, Rompree P, Papadakis A. Periodontal effects of surgically assisted rapid palatal expansion evaluated clinically and with cone-beam computerized tomography: 6-month preliminary results. Am J Orthod Dentofacial Orthop. 2011;139:117–128. Akkaya S, Lorenzon S, Ucem TT. A comparison of sagittal and vertical effects between bonded rapid and slow maxillary expansion procedures. Eur J Orthod. 1999;21: 175–180. Sun Z, Smith T, Kortam S, Kim DG, Tee BC, Fields H. Effect of bone thickness on alveolar bone-height measurements from cone-beam computed tomography images. Am J Orthod Dentofacial Orthop. 2011 Feb;139:e117–e127. Hatcher DC, Aboudara CL. Diagnosis goes digital. Am J Orthod Dentofacial Orthop. 2004;125:512–515. Ribeiro G, Locks A, Pereira J, Brunetto M. Analysis of rapid maxillary expansion using cone-beam computed tomography. Dent Press J Orthod. 2010;15:107–112. Leung CC, Palomo L, Griffith R, Hans MG. Accuracy and reliability of cone-beam computed tomography for measuring alveolar bone height and detecting bony dehiscences and fenestrations. Am J Orthod Dentofacial Orthop. 2010; 137:109–119. Molen AD. Considerations in the use of cone-beam computed tomography for buccal bone measurements. Am J Orthod Dentofacial Orthop. 2010;137:130–135.
Angle Orthodontist, Vol 85, No 5, 2015
