Original Article

Outcome assessment of lingual and labial appliances compared with cephalometric analysis, peer assessment rating, and objective grading system in Angle Class II extraction cases Toru Deguchia; Fumie Teraob; Tomo Aonumac; Tomoki Kataokad; Yasuyo Sugawarad; Takashi Yamashiroe; Teruko Takano-Yamamotof ABSTRACT Objective: To validate our hypothesis that there would be significant differences in treatment outcomes, including cephalometric values, degree of root resorption, occlusal indices, and functional aspect, between cases treated with labial and lingual appliances. Materials and Methods: Twenty-four consecutively treated Class II cases with extractions and lingual appliance were compared with 25 matched cases treated with extraction and labial appliance. Orthodontic treatment outcomes were evaluated by cephalometric analysis, peer assessment rating, and an objective grading system (OGS). Additionally, functional analysis was also performed in both groups after orthodontic treatment. Statistical comparison was performed using the Wilcoxon signed rank test within the groups, and the Mann-Whitney U-test was used to compare between the labial and lingual groups. Results: The only significant difference between the groups was that the interincisal angle was larger in the lingual group than in the labial group. OGS evaluation showed that control over root angulation was significantly worse in the lingual group than in the labial group. There was no significant difference between groups in the amount of root resorption or in functional evaluation. Conclusions: Generally, lingual appliances offer comparable treatment results to those obtained with labial appliances. However, care should be taken with lingual appliances because they are more prone to produce uprighted incisors and root angulation. (Angle Orthod. 2015;85:400–407.) KEY WORDS: Lingual appliance; Clinical outcome; Peer assessment rating; Objective grading system INTRODUCTION

Associate Professor, Division of Orthodontics, The Ohio State University College of Dentistry, Columbus, Ohio; and Adjunct Instructor, Division of Orthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan. b Assistant Professor, Department of Orthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan. c Graduate Student, Division of Orthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan. d Assistant Professor, Department of Orthodontics and Dentofacial Orthopedics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. e Professor and Chair, Division of Orthodontics, Department of Orthodontics and Dentofacial Orthopedics, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. f Professor and Chair, Division of Orthodontics, Tohoku University Graduate School of Dentistry, Sendai, Japan. Corresponding author: Dr Teruko Takano-Yamamoto, Division of Orthodontics and Dentofacial Orthopedics, Tohoku University Graduate School of Dentistry, 4-1, Seiryomachi, Aoba-ku, Sendai, 980-8575, Japan (e-mail: [email protected]) a

In some Asian countries, many patients refuse orthodontic treatment because of concerns related to the esthetics of labial appliances. The use of lingual appliances is a commonly used alternative, but compared to labial appliances, these are thought to result in different clinical outcomes, such as ‘‘bite opening,’’1 decreased axial inclination of the maxillary incisors,2 and reduced torque control.3 The short interbracket distance in lingual appliances is also problematic, especially during detailing,4 and the delivery of uncontrolled forces and moments may put the teeth at risk of root resorption.5 Past studies1,6 have mainly used cephalometric analysis to evaluate the clinical outcome of lingual appliances, but occlusal indices are rarely included. However, cephalometric analysis is not the only way to monitor changes in premolar and molar overjet (OJ) and problems with torque. Several studies have evaluated the severity of malocclusion using the discrepancy index (DI),7 whereas clinical orthodontic outcomes can be tested using occlusal indices, such

Accepted: July 2014. Submitted: March 2014. Published Online: August 25, 2014 G 2015 by The EH Angle Education and Research Foundation, Inc. Angle Orthodontist, Vol 85, No 3, 2015

400

DOI: 10.2319/031014-173.1

401

OUTCOME ASSESSMENT OF LINGUAL AND LABIAL APPLIANCES

as peer assessment rating (PAR) and the objective grading system (OGS).8,9 There have been several biomechanical and laboratory studies2,10,11 and case reports12 related to lingual appliances, but only a few clinical studies1,6 have compared their clinical outcome with that of labial appliances. Furthermore, these clinical studies are rather outdated and therefore have limited relevance to modern lingual appliances, which have undergone significant improvements in terms of bracket design, methods of setup, and indirect bonding techniques. In the present study, we hypothesized that there could be significant differences between lingual and labial appliances in terms of the clinical outcomes (including cephalometric values, the degree of root resorption, PAR, OGS, and functional evaluation13) when treating Class II cases with premolar extraction. MATERIALS AND METHODS The study protocol was reviewed and approved by the Institutional Board of Okayama University. This retrospective study used data from the first 24 consecutive cases that met the inclusion criteria for the lingual cases and compared these cases with 25 matched labial cases. The main variables within these groups were age, sex, and severity of the malocclusion. All eligible patients (ie, those who met the Okayama University Hospital criteria and provided informed consent for their participation) were included in the analysis. The criteria for case selection were as follows: N N N N N N

No previous phase 1 treatment or surgical treatment; An age of at least 18 years at the start of treatment; Maxillary and mandibular first premolars extracted; Angle Class II malocclusion; Mandibular plane angle .30u; and No temporomandibular joint dysfunction (TMD) symptoms.

The labial group comprised five men and 20 women with an average (6 standard deviation [SD]) age of 24.2 6 4.1 years. The lingual group consisted of four men and 20 women with an average age of 26.4 6 4.7 years. The same clinician (Dr Takano-Yamamoto) diagnosed and reviewed all patients at 6-month intervals to assess their responses to a standardized and common treatment sequence. All patients were treated with 0.018-inch slot brackets. Lingual cases were treated with STb lingual brackets (Ormco, Orange, Calif).14 The wire sequence in all labial cases was 0.014- or 0.016-inch nickel-titanium (Ni-Ti), 0.016 3 0.022-inch Ni-Ti, 0.016 3 0.022-inch stainless steel (SS), and 0.017 3 0.022-inch SS. The wire sequence in all

Table 1.

Pretreatment Discrepancy Index (DI) Scoresa Labial

Lingual

DI

Mean

SD

Mean

SD

OJ OB AOB LOB Crowd Occl LPX BPX ANB SNMp IMPA Total

2.9 1.9 0.3 0.4 4.7 2.3 0.3 0.5 2.4 4.6 1.0 21.3

2.0 1.4 0.8 1.4 3.0 2.7 0.7 0.8 2.9 9.6 3.3 11.1

2.8 2.1 0.3 0.6 5.0 2.5 0.7 0.4 2.2 4.4 1.1 22.1

0.9 2.0 1.0 2.0 2.3 2.5 1.1 1.4 2.6 8.4 3.8 11.6

a

SD indicates standard deviation.

lingual cases was 0.014- or 0.016-inch Ni-Ti, 0.018inch titanium-molybdenum alloy (TMA) or 0.016-inch SS, 0.017 3 0.022-inch copper (Co)-Ni-Ti, 0.0175 3 0.0175-inch TMA or 0.016 3 0.016-inch SS, 0.016 3 0.022-inch SS or 0.017 3 0.022-inch SS. Anterior retraction was by en mass retraction in all cases. A transpalatal arch or Nance appliance was required in both groups. Evaluation by Occlusal Indices DI (Table 1) and PAR (Table 2) were used to analyze the severity of each case. PAR and OGS were used for posttreatment evaluation to analyze the quality of the finished cases in both groups. Radiographic Evaluation Eight angular parameters (Figure 1) and 11 linear parameters (Figure 2) were analyzed. Root resorption was quantitatively estimated from periapical radiographic films.15 Functional Evaluation Functional evaluation was performed pre- and posttreatment using a 6–degrees of freedom jawmovement recording system (Gnathohexagraph system, version 1.31; Ono Sokki, Kanagawa, Japan), the operation of which has been described elsewhere.13 Each subject was required to demonstrate maximal voluntary jaw opening and dynamic protrusive and lateral excursive movements with the teeth in contact. Method Error All cephalometric tracings and occlusal cast measurements were performed by the same examiner. All cephalometric (Table 3), OGS (Table 4), and root resorption measurements were repeated after 4 weeks, Angle Orthodontist, Vol 85, No 3, 2015

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DEGUCHI, TERAO, AONUMA, KATAOKA, SUGAWARA, YAMASHIRO, TAKANO-YAMAMOTO

Table 2. Peer Assessment Rating (PAR) Scoresa Labial Pretreatment

Lingual Posttreatment

Pretreatment

Posttreatment

PAR

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mx.Ant. Mx.Post. Md.Ant. Md.Post. AP Vertical Transverse Overjet Overbite Midline Total United States UK

5.9 4.5 4.2 4.8 1.9 0.1 0.4 2.1 0.7 0.7 25.0 29.5 38.3

3.5 3.3 3.7 3.2 1.0 0.2 0.8 1.5 1.0 0.6 9.6 12.1 15.6

0.0* 1.1* 0.1* 0.9* 1.0* 0.0 0.1* 0.5* 0.1* 0.2 4.0* 6.7* 7.2*

0.0 1.4 0.3 1.0 1.0 0.0 0.7 0.5 0.3 0.4 2.2 4.1 3.6

4.7 6.4 4.7 6.4 1.2 0.0 1.3 2.1 0.5 0.7 28.0 30.1 41.0

2.8 4.4 3.1 3.0 1.5 0.0 1.7 1.3 0.8 0.6 7.2 11.2 10.7

0.2* 2.0* 0.1* 1.3* 0.4* 0.0 0.1* 0.3* 0.1* 0.1* 4.2* 5.0* 6.3*

0.4 1.5 0.3 1.1 0.8 0.0 0.3 0.0 0.5 0.2 2.2 2.5 2.6

* SD indicates standard deviation.

and the method error was calculated using the following equation: rffiffiffiffiffiffiffiffiffiffi SD 2 Sx ~ , 2N where Sx is the measurement error, D is the difference between duplicate measurements, and N is the number of duplicate measurements.16

Statistics The Wilcoxon signed rank test was used to examine the difference between pre- and posttreatment cephalometric analysis in each group. Because the sample size was small and the data were paired and nonparametric, we used the Mann-Whitney U-test to compare the cephalometric analyses and OGS scores between the two groups. P . .05 was considered

Figure 1. Angular measurements. 1. SNA angle (SNA); 2. SNB angle (SNB); 3. ANB angle (ANB); 4. SN to mandibular plane (Mp-SN); 5. SN to occlusal plane (Occl Pl); 6. SN to maxillary incisal (SN-U1); 7. mandibular plane to mandibular incisor (L1-Mp); and 8. interincisal angle (IIA). Angle Orthodontist, Vol 85, No 3, 2015

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OUTCOME ASSESSMENT OF LINGUAL AND LABIAL APPLIANCES

Figure 2. Linear measurements. 1. Anterior cranial base (S-N); 2. Anterior facial height (N-Me); 3. Lower anterior facial height (Me/PP); 4. Horizontal distance between the maxillary and mandibular incisal edges (OJ); 5. Vertical distance between the maxillary and mandibular incisal edges (OB); 6. Maxillary incisal edge to palatal plane (PP-U1); 7. Maxillary molar cusp to palatal plane (PP-U6); 8. Horizontal distance between pterygomaxillary fissure and maxillary molar cusp vertical on palatal plane (PTM-U6/PP); 9. Mandibular incisal edge to mandibular plane (Mp-L1); 10. Mandibular molar cusp to mandibular plane (Mp-L6); and 11. horizontal distance between point B and mandibular molar cusp vertical on mandibular plane (L6-B/Mp).

insignificant. Statistical analyses were performed using Statview software (SPSS, Chicago, Ill). RESULTS Measurement errors were 0.16 mm, 0.26u, 3.2 points, and 0.11 mm for linear cephalometric, angular cephalometric, OGS, and root resorption measurements, respectively. A high intraclass correlation coefficient of reliability (c) was observed between the two scoring sessions in both cephalometric (c 5 0.95) and OGS (c 5 0.92) analyses. Pretreatment Variables for the DI analysis are presented in Table 1. The average DI scores (6SD) were 21.3 6 11.1 inches in the labial group and 22.1 6 11.6 inches in the lingual group. There was no significant difference between the two groups in any of the analyzed variables before treatment. The total unweighted pretreatment PAR scores (mean 6 SD) were not significantly different, at 25.0 6 9.6 and 28.0 6 7.2, for labial and lingual treatments, respectively (Table 2). Thus, the two groups had comparable occlusal

features and severity of malocclusion. The cephalometric characteristics are presented in Table 3. There were no significant differences between the groups in any of the analyzed cephalometric measurements. Posttreatment The average treatment times were 29.4 6 5.6 months and 32.5 6 6.7 months in the labial and lingual groups, respectively. This difference was not significant. There were significant differences in both groups between the pre- and posttreatment PAR scores for most variables (Table 2), but not between the two groups in terms of posttreatment PAR scores. In both labial and lingual groups, a significant difference was observed between pre- and posttreatment cephalometric values of SN-U1, IIA, OJ, and PTM-U6/PP (Table 3). The only significant posttreatment difference observed between the two groups was for IIA. Significantly more retraction of both maxillary and mandibular incisors was observed in the lingual group. OGS evaluation was 24.5 6 7.9 and 25.3 6 6.7 in the labial and lingual groups, respectively, and the only significant difference between groups was in the Angle Orthodontist, Vol 85, No 3, 2015

Outcome assessment of lingual and labial appliances compared with cephalometric analysis, peer assessment rating, and objective grading system in Angle Class II extraction cases.

To validate our hypothesis that there would be significant differences in treatment outcomes, including cephalometric values, degree of root resorptio...
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