Age-Related Long-Term Posttreatment Occlusal and Arch Changes

Objective:To evaluate differences in long-term postretention changes between adolescents and adults.Materials and Methods:The sample included 96 subjects, 51 adolescents and 45 adults (14.2 ± 0.8 and 21.5 ± 6.8 years of age, respectively, at the end of treatment) retained for 3 years and followed approximately 16 years post treatment, who were randomly selected from two private practices. Prior to treatment, 38 and 58 had Class I and Class II malocclusions, respectively.Results:With the exception of adult midlines, all of the occlusal variables (overjet [0.50–0.77 mm], overbite [0.85–0.95 mm], the maxillary incisor irregularity [0.69–0.80 mm], the mandibular incisor irregularity [0.85–1.50 mm] and the PAR score [0.86–1.92 points]) showed significant increases over time. Adolescents consistently showed greater increases of the occlusal variables than adults, with mandibular incisor irregularity and the PAR index attaining statistically significant (P < .05) levels. Arch length and mandibular intercanine width showed statistically significant decreases over time in both groups; maxillary intercanine and intermolar widths did not change significantly. Overjet increased significantly more in Class II patients than in Class I patients, whereas Class I patients showed significantly greater decreases in mandibular intermolar width than Class II patients.Conclusions:Over the 16-year posttreatment period, adolescents showed significantly greater increases in mandibular incisor irregularity, and the PAR index than adults. Treated Class I patients demonstrated less increase in overjet and greater decreases in mandibular intermolar width than Class II patients.     

Long-Term Effects of Rapid Maxillary Expansion Followed by Fixed Appliances

Objective:To evaluate the long-term changes in maxillary arch widths, overjet, and overbite in patients who were treated with rapid maxillary expansion (RME) followed by edgewise appliances.Materials and Methods:The material for the study consisted of study casts taken from 41 patients (19 males, 22 females) on four different occasions (before treatment, T1; after RME, T2; after treatment, T3; and during follow-up period, T4). The upper intercanine, interpremolar, and intermolar widths and overjet and overbite were measured on each set of study casts. Mean age of the subjects was 13.2 ± 1.3 years (range, 11.2–16.9 years) at T1, 13.3 ± 1.3 years (range, 11.3–17 years) at T2, 15.5 ± 1.4 years (range, 13.1–18.8 years) at T3, and 20.4 ± 1.6 years (range, 17.9–24.8 years) at T4.Results:The net increase in intercanine width, interpremolar width, intermolar width, overjet, and overbite was 1.4 ± 2.4 mm, 4.6 ± 2.6 mm, 4.3 ± 2.5 mm, 0.1 ± 0.6 mm, and 0.2 ± 0.6 mm, respectively, and the relapse rates were 37% for intercanine width, 19% for interpremolar width, and 17% for intermolar width at the end of the follow-up period.Conclusions:A significant amount of relapse occurred in maxillary arch widths at the postretention assessment, the greatest being in intercanine width. RME significantly decreased overbite and increased overjet, and a statistically significant decrease was observed in both overbite and overjet at the postretention assessment.     

Aging in the craniofacial complex

OBJECTIVE: To describe the dental arch changes occurring after adolescence through the sixth decade of life. MATERIALS AND METHODS: Longitudinal dental casts from 40 patients (20 male and 20 female) were digitized and analyzed. Measurements were recorded after the presumed cessation of circumpubertal growth (T1), at approximately 47 years of age (T2), and at least one decade later (T3) were compared. RESULTS: The majority of the measurements were found to have a significant time effect, demonstrating at least some level of change throughout the aging process (T1-T3). Exceptions to this observation were the posterior maxillary arch width measurements, mandibular intermolar and interpremolar (as measured at the second premolars) widths, the maxillary incisor irregularity index, overjet, overbite, and curve of Spee. The T1-T3 changes reflected for the most part the T1- T2 changes, while the T2-T3 changes affected overall modifications only for the mandibular intercanine width and maxillary depth, as measured at the second premolars. All changes reflected a decrease in arch width, depth, and perimeter, with a significant increase in the mandibular incisor irregularity index. CONCLUSIONS: The dental arches continue to change and adapt throughout life and into the sixth decade, though the degree of change decreases with time.     

上颌快速扩弓联合固定矫治器治疗的稳定性研究

目的 观察患者接受上颌快速扩弓联合直丝弓矫治器治疗后覆牙合、覆盖及上牙弓宽度的变化。方法 选择2003年2月—2008年1月于青岛市口腔医院进行治疗的患者37例（男19例,女18例）,将患者分为4个不同的时期进行测量（N1:治疗前;N2:进行上颌快速扩弓后;N3:固定治疗后;N4:保持1年后）。分别测量每位患者的上颌尖牙间宽度、前磨牙间宽度、磨牙间宽度,并对前牙覆盖和覆牙合进行测量。患者的平均年龄（11.3±1.4）岁（10.2～15.3岁）。结果 治疗全部结束后、尖牙间宽度、前磨牙间宽度、磨牙间宽度、覆盖、覆牙合分别增加（2.6±2.3）mm、（3.7±2.1）mm、（5.2±2.5）mm、（0.3±0.6）mm、（-0.1±1.6）mm,患者复发率在尖牙宽度为47%,前磨牙间宽度为21％,磨牙间宽度为10%,覆盖复发率为9%,覆牙合为13%。结论 患者经过上颌快速扩弓后,在固定矫治阶段复发明显,保持阶段也有一定程度的复发。 上颌快速扩弓能够减小覆牙合,增加覆盖。     

欧米加阻挡曲扩弓法排齐和整平下颌拥挤牙列效果的临床研究

目的 评价下颌非拔牙病例中,澳丝弯制的欧米加阻挡曲扩弓法在传统直丝弓托槽上排齐和整平下颌拥挤牙列方面的临床效果。方法 选择58例正畸患者,年龄19~24岁,随机均分成2组,各29例,一组接受传统矫治方法,另一组采用欧米加阻挡曲扩弓法矫治。每种矫正方法又分为轻-中度拥挤（5 > Ⅱ > 2）和重度拥挤（Ⅱ > 5）两个亚组。下颌治疗结束时间以下牙弓完全排齐和整平为准。头颅侧位片评价下牙弓排齐和整平前后下切牙位置的变化;模型上测量下尖牙间距和下第一恒磨牙间距以反映牙弓宽度的变化。结果 2种排齐和整平的方法获得了相同程度的前牙区和后牙区扩弓量;就重度拥挤病例而言,欧米加阻挡曲扩弓法要明显快于传统方法（P=0.017）;结论 2种方法无论在切牙的唇向移动程度还是尖牙间距和磨牙间距的扩大情况等各方面几乎获得了同样的效果,对于严重拥挤的牙列,欧米加阻挡曲扩弓装置显示出更高的效率,是非常值得推荐的一种矫正方法。     

螺旋缩弓器治疗单侧后牙正锁的长期效果观察

目的：评价正畸螺旋缩弓器和MBT直丝弓矫治技术治疗单侧正锁后上颌牙弓宽度、前牙覆和覆盖的长期变化。方法：对23名（男13,女10）经正畸治疗后的患者4个阶段（治疗前,T1;螺旋缩弓后,T2;MBT治疗后,T3和去除保持器后2年,T4）的模型进行测量分析。结果：缩弓后上颌牙弓宽度明显减小（P〈0.05）。MBT治疗后尖牙宽度复发明显（P〈0.05）。停戴保持器2年后,尖牙宽度、第一前磨牙宽度、第一磨牙宽度、前牙覆和覆盖分别净减小（1.2±0.96）mm,（3.9±1.19）mm,（4.6±0.23）mm,（1.8±0.42）mm,（0.8±0.13）mm。结论：单侧正锁经正畸螺旋缩弓器和MBT直丝弓矫治技术治疗后上颌牙弓宽度稳定。     

Changes in dental arch measurements of young adults with normal occlusion--a longitudinal study

This study evaluates the longitudinal changes in occlusal dimensions in young adults. The sample was composed of 27 individuals (13 male and 14 female individuals) who presented dental Class I and normal occlusion, according to the inclusion protocol. All teeth were present except for the third molars. The mean age of the subjects was 21 years and two months initially and 28 years and four months at the end of the observation period. The measurements collected in both arches were overbite, overjet, intercanine and intermolar distances, irregularity index, and perimeter. All measurements were taken from study dental casts by a calibrated operator, using a digital caliper. The paired t-test was used to evaluate the changes, using the difference between the initial and final mean measurements. Data indicated that the overbite increased 0.39 mm, the incisor irregularity increased 0.38 mm in the upper arch and 0.54 mm in the lower arch, and the arch perimeter decreased 0.67 mm in the upper arch and 0.71 mm in the lower arch (P > .05). The other measurements did not show significant changes. No sexual dimorphism was observed. It could be concluded that occlusal dimensions change throughout adult life. In the sample studied, changes were statistically significant for overbite, incisors irregularity, and arch perimeter after a mean period of seven years and two months. These changes can be observed in both sexes.     

Nonextraction orthodontic therapy: posttreatment dental and skeletal stability

To assess the long-term stability of nonextraction orthodontic treatment, the dental cast and cephalometric records of 28 cases were evaluated. Thirty cephalometric and seven cast parameters were examined before treatment, posttreatment, and an average of almost 8 years postretention. Results showed overall long-term stability to be relatively good. Relapse patterns seen were similar in nature, but intermediate in extent, between untreated normals and four first premolar extraction cases. Significant decreases were seen in arch length and intercanine width during the postretention period despite minimal changes during treatment. Incisor irregularly increased slightly postretention; intermolar width, overjet, and overbite displayed considerable long-term stability. Mandibular incisor mesiodistal and faciolingual dimensions were not associated with either pretreatment or posttreatment incisor crowding. Class II malocclusions with large ANB values and shorter mandibular lengths showed increased incisor irregularity, shorter arch lengths, and deeper overbites at the postretention stage, suggesting that the amount and direction of facial growth may have been partially responsible for maturational changes seen during the postretention period.     

Maxillary arch changes with transpalatal arch treatment followed by full fixed appliances

Objective:To evaluate short- and long-term maxillary dental arch dimensional changes in patients treated with a transpalatal arch (TPA) during mixed dentition followed by full fixed appliances in the permanent dentition compared with an untreated sample.Materials and Methods:Dental casts and lateral cephalograms obtained from 36 consecutively treated patients before TPA treatment (T₀), after TPA treatment (T₁), after fixed appliance treatment (T₂), and a minimum of 3 years after fixed appliance treatment (T₃) were analyzed. The control group was matched as closely as possible. Arch widths, perimeter, and length, as well as crowding and incisor proclination, were evaluated.Results:In the treated group, intercanine, interpremolar, and intermolar widths and arch perimeter increased significantly at T₁. At T₂, only the intercanine width increase was still significant. At T₃ all arch dimensions decreased, remaining larger than they were at T₀. The arch length increased after T₁, significantly decreased at T₂, and slightly decreased at T₃. The crowding decreased significantly at T₁, was eliminated at T₂, and increased at T₃. At T_3, 50% of the patients showed relapse with crowding ranging from 0.5 to 2 mm. In the control group at T1, only slight changes were noted but crowding increased. At T2, crowding and upper incisor inclination increased but arch length decreased. At T3, intercuspid width, arch perimeter, and arch length continued to decrease, thereby increasing crowding.Conclusion:Maxillary dental arch dimensions changed significantly after TPA followed by treatment with fixed appliances. Relapse occurred to some extent, especially in intercanine width and arch perimeter, but most of the dental arch changes remained stable.     

Evaluation of relapse with thermoplastic retainers equipped with microsensors

ObjectivesTo examine relapse with thermoplastic retainers equipped with microsensors 1 year after treatment.Materials and MethodsA total of 42 patients (29 females, 13 males) treated with four premolar extractions were included in this study. Thermoplastic appliances equipped with TheraMon microsensors (Handelsagentur Gschladt, Hargelsberg, Austria) were used to assess daily wear time (DWT), and the patients were monitored at 2-month intervals for a period of 12 months. At the end of the follow-up, the following two groups were formed based on the mean DWT: short wear time (SWT; <9 h/d) and long wear time (LWT; ≥9 h/d). Digital models were constructed before treatment (T0), at debonding (T1), and 6 months (T2) and 12 months (T3) after debonding. Little''s Irregularity Index (LII) and the intercanine and intermolar widths, arch lengths, overjet, and overbite were calculated based on the digital models. Data were analyzed statistically.ResultsIrregularity and overjet increased, whereas transverse measurements and arch lengths decreased with time in both groups. During the retention period, overbite decreased in the SWT group but increased in the LWT group. There were significant differences between groups only in mandibular irregularity. The LII values of the SWT group were significantly higher than those of the LWT group for the T1–T2 and T1–T3 time intervals (P < .05).ConclusionsA mean DWT less than 9 hours/day was inadequate for controlling irregularity within clinically acceptable limits. A wear time of at least 9 h/d is recommended for the maintenance of mandibular anterior alignment.     

A new method of evaluating posterior occlusion and its relation to posttreatment occlusal changes.

The purpose of this study was to assess the relationship between posterior occlusion and posttreatment changes in other occlusal variables. Pretreatment (T1), posttreatment (T2), and postretention (T3) records were obtained for 49 Class I (n = 23) and Class II (n = 26) extraction cases. Overbite, overjet, mandibular incisor irregularity, right and left molar deviations, midline deviation, and mandibular arch length were measured, and occlusal registrations were made of each set of dental casts. The proximity of posterior occlusal surfaces was measured as the contact or near-contact areas at or below 300 microm thickness, based on the optical densities of scanned images of the posterior occlusal registrations. The treatment changes for overbite, overjet, right and left molar deviation, and arch length were significantly greater in the Class II group, and the reductions in incisor irregularity were greater in the Class I group. No other class differences were found. Overbite, overjet, and incisor irregularity increased after treatment, and arch length continued to decrease, with no significant class differences. Contact and near-contact areas at or below 300 microm constituted 7% of the functional occlusal table for both classes at the end of treatment, having decreased significantly in both groups (21% in Class I and 29% in Class II) during treatment. Because contact and near-contact areas increased in some patients and decreased in others, there were no significant posttreatment changes. Negative correlations were found between contact and near-contact areas at T2 and changes in overjet from T2 to T3, and between contact and near-contact areas at T3 and changes in overbite from T2 to T3. No relationships were found between posterior contact and near-contact area and incisor irregularity. We concluded that (1) the area of actual and near contacts at or below 300 microm decreased significantly with treatment, indicating that, despite excellent treatment results by conventional standards, the proximity of posterior occlusal surfaces lessened; (2) the proximity of the posterior occlusal surfaces should not be expected to increase posttreatment; (3) posttreatment contact and near-contact areas may be factors in overbite and overjet stability; and (4) posttreatment contact and near-contact areas are not related to incisor irregularity.     

Relapse of incisor crowding: A visit to the prince of salina

The management of the retention period after comprehensive orthodontic treatment is of great importance, as a primary goal of clinician. Considerable controversy still surrounds the problem of stability after the retention period. Many studies analyze factors associated to the presence of crowding or incisor irregularity and find predictive features on its relapse. Most studies have reported little o no correlation between the treatment changes in the biological parameters - clinical, biometric (irregularity index, intermolar width, intercanine width, arch length, overjet, overbite), or cephalometric variables- that ocurred and the posttretament and postretention changes that may predict their future development. This article provides a bibliographical overview on the relapse of dental alignment in treated cases. In a brief historical introduction, the first studies on the long-term stability of orthodontic results are analysed. The article then goes on to assess studies that focus attention on anteroinferior alignment before finally studying relapse of upper crowding. It concludes by making some final comments in the light of the bibliography provided and the differents schools regarding retention needs and methods. Key words:Retention, stability, irregularity, dental alignment.     

An assessment of conventional and self-ligating brackets in Class I maxillary constriction patients

Objective:To evaluate two different treatment systems with regard to incisor position, transverse dimension changes in maxillary arch, changes in maxillary molar inclinations, clinical periodontal parameters, and pain intensity in patients with a Class I malocclusion.Materials and Methods:Seventeen patients (with a mean age of 14.5 years) underwent orthodontic treatment with the Roth prescribed edgewise bracket systems after expanding the maxillary arch with a quad-helix appliance, and 16 patients (with a mean age of 14.8 years) underwent orthodontic treatment with the Damon 3MX bracket system. Each subject''s lateral cephalometric and posteroanterior radiographs and dental casts were obtained at the beginning of the treatment and after debonding. In addition to these, the periodontal index and pain scores were taken.Results:Cephalometric data showed that in both treatment systems, overjet value decreased and maxillary and mandibular incisors proclined. Posteroanterior measurements demonstrated a greater increase in the maxillary molar inclination in the Damon group. Significant increase of maxillary intercanine, interpremolar, and intermolar widths was shown in both systems. Periodontal index and pain score changes between different observation periods were the same.Conclusions:The conventional and Damon systems were found similar with regard to the incisor position, transverse dimension changes in maxillary arch, clinical periodontal parameters, and pain intensity. The only significant difference was that the Damon system inclined the maxillary molars more buccally than the conventional group.     

Maturation of untreated normal occlusions

The dental casts of 65 untreated normal occlusions were evaluated to determine the nature and extent of the developmental maturation process of the normal dentition. Six dental parameters were examined in the mixed dentition (9 to 10 years), early permanent dentition (12 to 13 years), and early adulthood (19 to 20 years). Results showed decreases in arch length and intercanine width; minimal overall changes in intermolar width, overjet, and overbite; and increases in incisor irregularity. Females showed more severe changes than males. The individual changes found were not correlated to changes in any of the other parameters measured. No associations or predictors of clinical value were found. The changes found in a sample of untreated normals were similar in nature but lesser in extent than postretention changes found in a sample of treated cases.     

Short- and long-term evaluation of mandibular dental arch dimensional changes in patients treated with a lip bumper during mixed dentition followed by fixed appliances

Objective:To evaluate short- and long-term mandibular dental arch changes in patients treated with a lip bumper during the mixed dentition followed by fixed appliances, compared with a matched control sample.Materials and Methods:Dental casts and lateral cephalograms obtained from 31 consecutively treated patients before (T₀) and after (T₁) lip bumper, after fixed appliances (T₂), and a minimum of 3 years after fixed appliances (T₃) were analyzed. The control group was matched as closely as possible. Arch width, arch perimeter, arch length, and incisor proclination were evaluated. Repeated measures ANOVA was used to analyze changes in measurements over all four time points between treatment and control groups.Results:Arch widths and crowding were always significantly different except at T₂−T₁. At T₁−T₀, only crowding decreased 3.2 mm while intercanine, interpremolar, and intermolar widths increased by 3.8, 3.3, and 3.9 mm, respectively. Changes at T₃−T₂ showed a significant decrease of 2.1 mm for crowding and an increase of 3.5, 2.9, 2.7, and 0.8 mm for intercanine, interpremolar, and intermolar widths and arch perimeter, respectively. Finally, at T₃−T₀, the reduction in crowding of 5.03 mm was significant and clinically important in the treated group. The differences between intercanine, interpremolar, and intermolar widths were also significant (2.1, 3.8, and 3.6 mm, respectively). All those differences favored the treated group.Conclusions:Mandibular dental arch dimensions were significantly changed after lip bumper treatment. At follow-up, all arch widths were slightly decreased, generating an increase of 0.4 mm in crowding, considered clinically irrelevant. Overall changes remained stable after an average 6.3-year follow-up.     

A retrospective study of Angle Class I malocclusions treated orthodontically without extractions using two palatal expansion methods.

The correction and relapse of mandibular anterior crowding was evaluated in a population of 58 patients with Angle Class I malocclusion who were treated orthodontically without extraction of permanent teeth. The subjects were retrospectively evaluated from records taken before treatment, posttreatment, and postretention. The postretention period averaged 8 years (minimum of 4 and maximum of 20 years). All cases in Groups A and B were given orthopedic treatment to develop the maxillary apical base in the transverse and anteroposterior planes. Group A was treated with expansion of the inner bow of the face bow appliance (Kloehn), and Group B was treated with the Haas palatal expansion appliance. Both groups were then treated orthodontically with tandem mechanics. The response variables measured were: overbite, overjet, intercanine distance, intermolar distance, and irregularity index. Study groups A and B were not significantly different for subject age, retention, or postretention time. Moreover, the groups did not show significant difference for any of the response variables before treatment. However, there was a statistically significant difference in the treatment times (P =.0133). A statistically significant treatment effect was observed for most response variables in the groups. Overbite, overjet, and irregularity index were significantly reduced, intermolar distance was significantly increased, and intercanine distance showed no significant change in Groups A and B. In the postretention period, there was a tendency for variables to change slightly toward their before treatment values but no compromise of orthodontic correction was noted. The irregularity index in Group A was corrected from 4.8 to 1.1 mm and remained at 1.1 mm in the postretention period. The irregularity index in Group B was corrected from 5.1 to 1.2 mm (P =.0001) and changed slightly from 1. 2 to 1.7 mm (P =.0540) in the postretention period. We concluded that mandibular incisors tended to become more crowded postretention. However, in contrast to previous reports, we calculate this relapse to be small. Neither before treatment nor posttreatment variables were predictive of relapse.     

Mandibular incisor alignment and dental arch changes 1 year after extraction of deciduous canines

This study investigated the early effects on mandibular incisor irregularity and rotation together with dental arch dimensions of the extraction of four deciduous canines. Children, during early mixed dentition, were randomized into one extraction (n = 32) and one control (n = 41) group. Dental casts from baseline (T0) and 1 year follow-up (T1) were used to evaluate changes in the irregularity index and in mandibular incisor rotation, dental arch dimensions, overjet, and overbite. Median mandibular incisor irregularity decreased over time, significantly more in the extraction than the control group (1.2 versus 0.7 mm; P < 0.01), with wide ranges in both groups. Rotational changes greater than 10 degrees for lateral incisors were twice as common in the extraction group (42 versus 20 per cent; P < 0.01). Central incisors displayed only minor changes in both groups. The correlation between changes in irregularity index and changes in incisor rotation was weak in both groups (r(s) < 0.3 not significant). According to professional assessment of overall alignment, 84 per cent in the extraction group versus 34 per cent in the control group (P < 0.001) improved from T0 to T1. A significant decrease in maxillary and mandibular arch length and circumference from T0 to T1 was recorded in the extraction group (1.3, 1.1 mm and 2.4, 2.0 mm, respectively; P < 0.001), while arch dimensions were preserved in the control group. To conclude, 1 year after extraction of the deciduous canines, small improvements in mandibular incisor alignment were seen, together with reduced arch dimensions. Little's index underestimated malalignment related to tooth rotation.     

Effects of mandibular incisor extraction on anterior occlusion in adults with Class III malocclusion and reduced overbite

The aim of this study was to assess the treatment outcome and changes in mandibular incisor position after extraction of one single incisor in 36 adult orthodontic cases with combined Class III and open bite tendencies. The cases consisted of 21 female and 15 male patients with an average age of 27.8 years (standard deviation [SD], 11.1 years) at the start. Fixed 0.018-inch Edgewise appliances were used in both arches in 19 patients and in the mandibular arch in 17 patients. Average treatment time was 18 months (SD, 7.1 months). Pretreatment ANB was 0.5^o (SD, 2.7°), overjet 1.4 mm (SD, 1.9 mm), and overbite 1.5 mm (SD, 1.1 mm). The lower incisors were 3.6 mm (SD, 2.8 mm) in front of the APg-line, and the Averaged Irregularity Index was 1.1 mm (SD, 0.6 mm). Records representing pretreatment (T1), posttreatment (T2), and average 4.3 years (SD, 2.3 years) retention (T3) included cephalograms, panoramic films, intraoral and extraoral photographs, and plaster models. All cast measurements were made with digital calipers. On the cephalograms, the lower incisor tips moved posteriorly 1.7 mm (SD, 2.0 mm) and occlusally 1.5 mm (SD, 1.8 mm) from pretreatment to posttreatment. Relative to the x-axis, they tipped lingually 5.9^o (SD, 5.6°). On the cast analysis, overjet increased 1.0 mm (SD, 1.9 mm) and 1.5 mm (SD, 1.5 mm) for the maxillary central and lateral incisors, respectively, whereas overbite increased 0.6 mm for both the central and lateral incisors. The intercanine width was reduced by 3.3 mm (SD, 2.0 mm), while the intermolar width was unchanged. The Average Irregularity Index was reduced from 1.1 to 0.2 mm. Arch-length was reduced 3.6 mm from pretreatment to posttreatment, and another 0.3 mm from posttreatment to 4.3-years retention. Other changes from posttreatment to 4.3-years retention were slight. No loss of the interdental gingival papillae was normally observed. It is concluded that the extraction of one mandibular incisor can lead to satisfactory treatment results in adults with mild Class III malocclusion and reduced overbite, particularly when coupled with a large mandibular intercanine width and minor crowding, and some mandibular tooth size excess. However, the orthodontic treatment frequently became more complicated and time-consuming than expected at the start. (Am J Orthod Dentofacial Orthop 1999;115:113-24)     

Does overbite reduction affect smile esthetics?

Objectives:To compare the effects of two common methods of overbite reduction on smile esthetics.Materials and Methods:A prospective clinical trial was conducted with 32 patients in whom overbite reduction was achieved using a maxillary incisor intrusion arch (18 patients) or flat anterior bite plate (14 patients). Clinical and cephalometric records were compared pretreatment (T1), after overbite reduction (T2), and posttreatment (T3).Results:Both treatment groups experienced a reduction in overbite and maxillary and mandibular incisor proclination during treatment (T1–T3). The center of resistance of the maxillary incisor and the incisal edge was significantly intruded in the intrusion arch group during overbite reduction (T1–T2). However, most of the intrusion of the center of resistance was lost by the end of treatment (T2–T3). Both treatment groups experienced a reduction in maxillary incisor display and flattening of the smile arc during overbite reduction.Conclusions:Both overbite reduction methods caused a decrease in incisor display and flattening of the smile arc. Smiles were improved in some patients by the end of treatment. However, reduction in incisor display persisted. Clinicians should take precautions to prevent negative effects of overbite reduction.