Mandibular Incisor Irregularity Research Articles

Retention using braided bonded wires: a 2-year follow-up of the dentition and oral hygiene with predictors of relapse

Abstract Objective To assess gingival health and predictors of relapse related to braided-wire bonded retainers after the active phase of comprehensive orthodontic treatment. Materials and methods Fifty-one subjects were recruited in a prospective study of whom 42 were available for analysis after 2 years of retention (pre-therapeutic ages 11–18 years; 66% female). A rectangular wire retainer (0.027 × 0.011″) was bonded to the mandibular incisors. Little’s index of incisor irregularity; intercanine width; the accumulation of biofilm, calculus and gingivitis; and the incidence of retainer detachment, were recorded. Subjects were examined before orthodontic therapy, upon therapy completion, and after 2 years of retention. Results The incidence of retainer detachment over the 2 years was 27%. The post-treatment incidence of irregularity was 17%, and intercanine width reduction was 24%. Calculus accumulation increased significantly during retention (p < 0.001) but not the extent of gingivitis. A multiple logistic regression demonstrated that an increase of mandibular intercanine width by ≥3 mm correspondingly increased the odds of relapse 14.3 times (95% confidence interval [CI], 1.1–196.1; p = 0.046). Patients presenting with retainer failure were 10 times (95% CI 1.6–62.8; p = 0.014) more likely to experience relapse. Subjects who experienced relapse had retainer failure earlier than those without relapse (19 vs. 23 months; p = 0.003). The occurence of relapse was not related to a treatment change in incisor irregularity, the duration of treatment, the age of the patient, gender nor to a change of intercanine width during retention. Conclusion Post-treatment changes in the mandibular arch incorporating bonded retainers were not large, but were common. An increase in mandibular incisor irregularity during retention is mostly related to treatment-induced intercanine width expansion. The bonded retainer often detached and increased calculus accumulation.

Incisor irregularity and dental arch dimensions changes in subjects with different severity of anterior crowding: a 37-year follow-up

BackgroundOcclusal stability is one of the goals of orthodontic treatment, and keeping teeth aligned in the long term is a challenge for the orthodontist. This study aimed to compare the long-term incisors irregularity and dental arches dimensions changes in subjects treated with 4 premolar extractions with different pretreatment Little's irregularity index (LII). The knowledge of long-term outcomes is evidence-based information for the prognosis of future treatments.MethodsIn total, 41 treated subjects were divided into two groups according to mandibular Little irregularity value at pretreatment (mild or severe). The maxillary and mandibular LII, transversal, and longitudinal widths were assessed at pretreatment, posttreatment, and 37-year posttreatment. Chi-square and independent t tests were used for intergroup comparison.ResultsThe groups presented similar behavior for all stages of maxillary and mandibular arch dimensions changes. Maxillary irregularity was corrected in both groups after treatment, and the alignment was acceptable in the long term. In the mild group, the mandibular incisor irregularity returned to pretreatment values in the long term. The mandibular LII increased in the severe group but did not return to pretreatment values in the long term.ConclusionsThe mild crowding group presented proportionally more relapse of mandibular incisor irregularity than the severe crowding group in the long term. Even so, the correction of mild and severe crowding with the extraction of 4 premolars showed satisfactory results in the long term, even with the presence of maturational changes and relapse.

Twenty-year follow-up of functional treatment with a bionator appliance: A retrospective dental cast analysis.

To investigate changes in dental arch configuration, relationship, and malocclusion directly after Class II malocclusion treatment with a Balters bionator modified by Ascher as well as 20 years after treatment. Orthodontic dental cast analysis of 18 patients with skeletal Class II treated with a bionator without any additional fixed therapy was performed with a digital caliper at three stages: before (T0), after (T1) and 20 years after (T2) treatment. Arch perimeter and depth, intermolar and intercanine distance, overjet, overbite, sagittal molar and canine relationship, mandibular incisor irregularity (Little's index), and malocclusion (PAR index) were assessed. During treatment (T0-T1), upper arch perimeter significantly increased with a significant decrease in the upper and lower arch perimeter long-term (T1-T2), whereas corresponding arch depths changed only slightly in both periods. Transverse intermolar width increased significantly during treatment, remaining almost constant from T1 to T2. Lower intercanine distance remained fairly unchanged during treatment, but decreased significantly during follow-up. Lower incisor irregularity improved slightly during treatment but increased significantly long-term. After treatment, sagittal molar relationships on both sides were improved, overjet and overbite reduced; these significant changes remained stable long-term. The peer assessment rating (PAR) index was significantly lower after treatment and increased insignificantly during follow-up. 20 years after bionator treatment without additional fixed appliances, the improved sagittal relationship and the reduced overjet and PAR index remained fairly stable. Long-term changes are most likely due to physiological aging processes and are not associated with bionator treatment.

The prevalence of clinically meaningful malocclusion among US adults.

The primary purpose of this study was to statistically evaluate age, ethnic and sex differences in the prevalence of clinically meaningful malocclusions among adults. A random sample of 8804 untreated US adults between 17 and 46years of age was selected from the Third National Health and Nutrition Examination Survey data. Three ethnic (non-Hispanic White, non-Hispanic Black and Mexican Americans) and three age (17-26, 27-36 and 37-46years) groups were evaluated. Subjects with and without clinically meaningful malocclusions were categorized based on the established cut-off values. Chi-square analyses were performed to determine differences in prevalence. The prevalence of clinically meaningful mandibular incisor irregularity, overjet and overbite increased significantly (P<0.05) with age, while posterior crossbite decreased. There were statistically significant ethnic differences in the prevalence of incisor irregularity, overbite, overjet, open bite and reverse overjet. Males had a significantly higher prevalence of clinically meaningful mandibular incisor irregularity, overbite, open bite and reverse overjet than females. One-third of US adults exhibited no clinically meaningful malocclusions. There are age, ethnic and sex differences in the prevalence of clinically meaningful malocclusions that characterize approximately two-thirds of untreated US adults.

Association between incisor irregularity and coronal caries: A population-based study.

The objective of this study was to investigate the association between incisor irregularity and anterior coronal caries by means of an arch-specific analysis among the U.S. population in the National Health and Nutritional Examination Survey (NHANES III) 1988-1994. This study analyzed data from 9049 participants who were surveyed from 1988 to 1994 as a part of the NHANES III. Participants with a complete set of fully erupted permanent anterior teeth in the maxillary and mandibular segments (ie, canine to canine), who completed an examination of occlusal characteristics and anterior dental caries, and who reported no previous orthodontic treatment were included in the study. Incisor irregularity per arch was determined with the use of the Little irregularity index. Anterior coronal caries per arch was defined as ≥1 surface with decayed or filled surface (CDFS ≥1). Analyses were conducted with the use of chi-square test and logistic regression modeling taking into account the complex sampling design of the survey. In the maxillary arch, 25.1% of the study population had maxillary anterior coronal caries experience (CDFS ≥1), whereas only 5.5% of the study population had mandibular anterior coronal caries experience (CDFS ≥1). In both arches, no statistically significant association between incisor irregularity and anterior coronal caries experience was found. Maxillary and mandibular incisor irregularity is not associated with anterior dental caries prevalence in a subset of NHANES III data that included mostly highly educated adult participants who were white, of medium socioeconomic status, and with high oral health compliance and oral self-care. Future well designed prospective cohort studies are needed to confirm these results. Clinicians are still encouraged to continue providing oral health education to their patients about the well established effect of incisor irregularity on plaque retention.

Comparison of anterior crowding relapse tendency in patients treated with incisor extraction, premolar extraction, and nonextraction treatment

Background and aimRelapse of incisor crowding is usually a serious challenge for orthodontists, and achieving long-term stable occlusion after treatment is one of the primary goals of orthodontic treatment. Stability of aligned incisors is unpredictable, and the difference is attributed to the type of malocclusion, treatment procedures, patient co-operation, or soft tissue growth and adaptability. Considering controversies in this issue, this study is aimed to compare various treatment plans used for incisor alignment in order to find the most useful one, which achieves long-term stability. MethodsThe study included 120 study casts from 40 patients with the mean age of 23.1 years and range of 15 to 38 years. The patients were treated with either nonextraction, single extraction, or premolar extraction and were evaluated at three time points, including T1 (before treatment), T2 (after treatment), and T3 (after retention). ResultsRelapse were observed in all three groups. The mean of mandibular incisor irregularity index was 0.37 ± 0.31, 0.37 ± 0.41, and 0.51 ± 0.47 in the nonextraction, premolar extraction, and incisor extraction groups, respectively. One-way analysis of variance suggested that there was no significant difference among the three groups in this regard (P = 0.2). ConclusionsGiven the results of this study, it appears that treatment modality in terms of extraction or nonextraction is not a major determinant in posttreatment relapse.

Effects of supplemental vibrational force on space closure, treatment duration, and occlusal outcome: A multicenter randomized clinical trial.

A multicenter parallel 3-arm randomized clinical trial was carried out in 3 university hospitals in the United Kingdom to investigate the effect of supplemental vibratory force on space closure and treatment outcome with fixed appliances. Eighty-one subjects less than 20years of age with mandibular incisor irregularity undergoing extraction-based fixed appliance treatment were randomly allocated to supplementary (20minutes/day) use of an intraoral vibrational device (AcceleDent; OrthoAccel Technologies, Houston, Tex) (n=29), an identical nonfunctional (sham) device (n=25), or fixed-appliance only (n=27). Space closure in the mandibular arch was measured from dental study casts taken at the start of space closure, at the next appointment, and at completion of space closure. Final records were taken at completion of treatment. Data were analyzed blindly on a per-protocol basis with descriptive statistics, 1-way analysis of variance, and linear regression modeling with 95% confidence intervals. Sixty-one subjects remained in the trial at start of space closure, with all 3 groups comparable for baseline characteristics. The overall median rate of initial mandibular arch space closure (primary outcome) was 0.89mm per month with no difference for either the AcceleDent group (difference, -0.09mm/month; 95% CI, -0.39 to 0.22mm/month; P=0.57) or the sham group (difference, -0.02mm/month; 95% CI, -0.32 to 0.29mm/month; P=0.91) compared with the fixed only group. Similarly, no significant differences were identified between groups for secondary outcomes, including overall treatment duration (median, 18.6months; P>0.05), number of visits (median, 12; P>0.05), and percentage of improvement in the Peer Assessment Rating (median, 90.0%; P>0.05). Supplemental vibratory force during orthodontic treatment with fixed appliances does not affect space closure, treatment duration, total number of visits, or final occlusal outcome. NCT02314975. The protocol was not published before trial commencement. AcceleDent units were donated by OrthoAccel Technologies; no contribution to the conduct or the writing of this study was made by the manufacturer.

Residents' journal review

Residents' journal review

The effect of conventional versus figure-of-eight module ligation on mandibular incisor alignment: a randomised controlled trial.

To determine whether using figure-of-eight modules affects the rate of lower incisor alignment compared with conventionally tied modules. Prospective randomised controlled trial. Orthodontic department at Queen's Hospital, Burton upon Trent, UK. One hundred and twenty participants were randomly allocated to conventional module or figure-of-eight module groups, stratified for extraction or non-extraction lower arch treatment. Eligibility criteria included patients who were 12-15 years of age at the start of treatment, in the permanent dentition, and had mandibular incisor irregularity of 5-10 mm (clinical observation). The primary outcome was the rate of lower incisor alignment during the first 12 weeks of orthodontic treatment. The secondary outcome was bracket failure rate. Lower labial segment alignment was measured on study models using the Little's Irregularity Index at the start (T0) of treatment, at 6 weeks (T1) and 12 weeks (T2). Case records were analysed to assess the number of bracket failures. The four groups were well matched at baseline with respect to gender, age and irregularity. All patients completed the trial and data were analysed on an intention to treat basis. In both ligation groups, the lower teeth aligned significantly faster when the treatment involved extractions, for the time periods T0-T1 and T0-T2 (p < 0.05). There were no statistically significant differences between conventional module and figure-of-eight module ligation on the rate of alignment (per month) for all three-time periods. The bracket failure rate was also similar in both test groups; 4.08% for conventional and 3.21% for figure-of-eight ligation. Ligation with figure-of-eight modules has no clinically significant effect on the rate of lower incisor alignment; it does not seem to hinder or quicken the alignment of teeth. There were no differences in the mean number of bracket failures per person.

Effect of supplemental vibrational force on orthodontically induced inflammatory root resorption: A multicenter randomized clinical trial.

A multicenter parallel 3-arm randomized clinical trial was carried out in 1 university and 2 district hospitals in the United Kingdom to investigate the effect of supplemental vibrational force on orthodontically induced inflammatory root resorption (OIIRR) during the alignment phase of fixed appliance therapy. Eighty-one subjects less than 20years old with mandibular incisor irregularity undergoing extraction-based fixed-appliance treatment were randomly allocated to supplementary (20minutes a day) use of an intraoral vibrational device (AcceleDent; OrthoAccel Technologies, Houston, Tex) (n=29), an identical nonfunctional (sham) device (n=25), or fixed appliances only (n=27). OIIRR was measured blindly from long-cone periapical radiographs of the maxillary right central incisor taken at the start of treatment and the end of alignment when a 0.019×0.025-in stainless steel archwire was placed (mean follow-up, 201.6days; 95% confidence interval [CI], 188.6-214.6days). Data were analyzed blindly on a per-protocol basis because losses to follow-up were minimal, with descriptive statistics, 1-way analysis of variance, and univariable and multivariable regression modeling. Nine patients were excluded from the analysis; they were evenly distributed across the groups. Mean overall OIIRR measured among the 72 patients was 1.08mm (95% CI, 0.89-1.27mm). Multivariable regression indicated no significant difference in OIIRR for the AcceleDent (difference, 0.22mm; 95% CI, -0.14-0.72; P=0.184) and AcceleDent sham groups (difference, 0.29mm; 95% CI, -0.15-0.99; P=0.147) compared with the fixed-appliance-only group, after accounting for patient sex, age, malocclusion, extraction pattern, alignment time, maximum pain experienced, history of dentoalveolar trauma, and initial root length of the maxillary right central incisor. No other side-effects were recorded apart from pain and OIIRR. The use of supplemental vibrational force during the alignment phase of fixed appliance orthodontic treatment does not affect OIIRR associated with the maxillary central incisor. ClinicalTrials.gov (NCT02314975). The protocol was not published before trial commencement. Functional and sham AcceleDent units were donated by the manufacturer; there was no contribution to the conduct or the writing of this study.

Relationship between mandibular incisor irregularity and type of occlusion in ankyloglossia.

To investigate the relationship between the lingual frenulum length with mandibular incisor irregularity and type of occlusion in children with ankyloglossia. Eighty children aged between 7 and 12 years with ankyloglossia enrolled in the study. The patients were classified according to Kotlow's classification. Mandibular incisor crowding was measured and the molar relationship was determined. The data were analysed statistically using Fisher's exact test, X2 and Pearson's correlation. Of the 80 patients, 45 (56.3%) had mild, 23 (28.8%) had moderate and 12 (15%) had severe ankyloglossia. Fifty-nine (73.8%) of the patients had mild irregularity, 18 (22.5%) had moderate and 3 (3.8%) had severe irregularity. In 56 (70%) of the patients, Class I occlusion was observed, 17 (21.3%) had Class II and 7 (8.8%) had Class III occlusion. No significant differences were found between types of ankyloglossia with mandibular incisor irregularity and occlusion types. A significant positive correlation was determined between the length of the lingual frenulum length and mandibular incisor irregularity. There were significant positive correlations between the lingual frenulum length, incisor irregularity and age. Mild and moderate types of ankyloglossia are unrelated to mandibular incisor crowding and occlusion type.

Thirty-two-year follow-up study of Herbst therapy: A biometric dental cast analysis

The aim of this study was to analyze the very long-term effects of Herbst treatment on toothposition and occlusion. Fourteen patients from a sample of 22 with Class II Division 1 malocclusions consecutively treated with the banded Herbst appliance were reexamined 32 years after therapy. Dental casts were analyzed from before (T1) and after (T2) treatment, and at 6 years (T3) and 32 years (T4) after treatment. Minor changes in maxillary and mandibular dental arch perimeters and arch widths were seen during treatment (T1-T2) and posttreatment (T2-T4). Mandibular incisor irregularity remained, on average, unchanged from T1 to T2 but increased continuously during the 32-year follow-up period (T2-T4). Class II molar and canine relationships were normalized in most patients from T1 to T2. During the early posttreatment period (T2-T3), there was a minor relapse; during the late posttreatment period (T3-T4), molar and canine relationships remained, on average, unchanged. Overjet and overbite were reduced to normal values in all subjects during treatment (T1-T2). After treatment (T2-T4), overjet remained, on average, unchanged, but overbite increased insignificantly. Thirty-two years after Herbst therapy, overall, acceptable long-term results were seen. Stability was found in 64% of the patients for sagittal molar relationships, in 14% for sagittal canine relationships, in 86% for overjet, and in 86% for overbite. A Class II relapse seemed to be caused by an unstable interdigitation of the occluding teeth, a persisting oral habit, or an insufficient retention regimen after treatment. Most posttreatment changes occurred during the first 6 years after treatment. After the age of 20 years, only minor changes were noted. Long-term posttreatment changes in maxillary and mandibular dental arch perimeters and widths as well as in mandibular incisor irregularity seemed to be independent of treatment and a result of physiologic dentoskeletal changes throughout adulthood.

Relapse revisited—again

Long-term changes in the dentitions of orthodontic patients have been studied. However, most studies in the literature report findings after only a few years posttreatment. In this study, we examined records an average of 24 years after active treatment. The purpose was to answer 2 questions: (1) does irregularity increase with time after treatment, and (2) how much relapse can be expected if a conservatively treated sample is recalled 2.5 decades after active treatment? The sample consisted of dental casts of 52 women who were treated in the mid-1970s to the early 1980s with 0.022 × 0.028-in standard edgewise appliances. Each was given a maxillary Hawley retainer and either a mandibular Hawley or a banded canine-to-canine retainer at debanding. Retention lasted 24 to 32 months. The same practitioner treated all the patients. The sample is one of convenience; specifically, inclusion depended only on each patient's willingness to return for a recall examination. Records were collected at 3 examinations for each patient: start of treatment, end of the active phase of treatment, and long-term retention recall. The long-term maxillary and mandibular casts were measured and occluded in maximum intercuspation. Variables were measured, including incisor overjet and overbite, buccal segment relationship of the first molars and canines, and incisor irregularity in each arch. Variables were measured on the casts with digital readout sliding calipers precise to 0.001 mm. Mandibular incisor irregularity at recall was less than 3.5 mm in 77% of the patients examined. Correction of the maxillary incisor irregularity remained relatively stable over the time interval studied. Buccal segment Class II correction remained stable at the recall examination. Orthodontic treatment can yield reasonably good long-term stability in both occlusal correction and tooth alignment.

Prediction of orthodontic treatment of surgically exposed unilateral maxillary impacted canine patients

To determine whether clinical variables associated with surgically exposed unilateral maxillary impacted canine cases are predictors for orthodontic treatment choices involving (1) extraction, (2) expansion, (3) extraction and expansion, or (4) nonextraction and nonexpansion. A retrospective study of records of 97 cases meeting the inclusion criteria with unilateral maxillary impacted canines from three private practices were reviewed for gender, age, molar classification, impaction location and angulation, and presence of pretreatment maxillary and mandibular casts and cephalograms. Maxillary and mandibular transverse dimensions and lower incisor crowding were obtained from occlusal cast images using custom computer software. Skeletal analysis and incisor angulation and position were obtained from digitized cephalometric tracings. Statistical comparisons were made to determine parameters orthodontists could use to develop an orthodontic treatment plan. Subjects with Class II end-on molars on the nonaffected side were less likely to have extraction and/or expansion. Subjects with extraction and/or expansion had decreased lower incisor to mandibular plane, available canine space, maxillary premolars, and molar transverse dimensions and an increased mandibular incisor Irregularity Index compared with nonextraction/nonexpansion subjects. Using a multiple-variable model, available canine space was the single most important predictor of extraction and/or expansion, followed by maxillary molar transverse dimension and mandibular incisor Irregularity Index. Available canine space, maxillary transverse dimension at the molars, and the mandibular incisor Irregularity Index serve as indicators for extraction and/or expansion in cases involving unilateral maxillary impacted canines requiring surgical exposure. Many of these cases are treated without extraction and/or expansion.

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.

Relapse of mandibular incisor alignment is not associated with the total posttreatment mandibular rotation

Our objective was to determine whether total posttreatment mandibular rotation is associated with mandibular incisor crowding after retention. Mandibular incisor irregularity (II) at least 10 years out of retention (T3) measured on dental casts from the postretention database at the University of Washington in Seattle was used to define subjects (II ≥6 mm, relapse group) and controls (II ≤3.5 mm, stable group). After matching patients and controls for the pretreatment II, the relapse group consisted of 33 subjects (17 boys, 16 girls; age at the end of treatment [T2], 15.0 years; follow-up, 16.8 years), and the stable group comprised 36 subjects (11 boys, 25 girls; age at T2, 16.0 years; follow-up, 15.1 years). On cephalograms taken at T2 and T3, facial morphology was evaluated, and total posttreatment mandibular rotation was measured with a structural method. Logistic regression analyses were used to determine the association between relapse and amount of total mandibular rotation. The models were adjusted for potentially confounding variables (age at T2, sex, length of follow-up, and intercanine width change during treatment). No association between total posttreatment mandibular rotation and relapse was found (P = 0.515). Total mandibular rotations were comparable in the relapse and stable groups (P = 0.386). Age at T2 was found to be correlated with long-term incisor stability (P = 0.030). Sex and intercanine width change during treatment were not related to relapse (P = 0.225 and P = 0.264, respectively). Total mandibular rotation is not associated with relapse of the mandibular incisors. Posttreatment skeletal and dental growth changes were comparable in the relapse and stable groups.

Editor's Comment and Q&A: Relapse of mandibular incisor alignment is not associated with the total posttreatment mandibular rotation

Introduction Our objective was to determine whether total posttreatment mandibular rotation is associated with mandibular incisor crowding after retention. Methods Mandibular incisor irregularity (II) at least 10 years out of retention (T3) measured on dental casts from the postretention database at the University of Washington in Seattle was used to define subjects (II ≥6 mm, relapse group) and controls (II ≤3.5 mm, stable group). After matching patients and controls for the pretreatment II, the relapse group consisted of 33 subjects (17 boys, 16 girls; age at the end of treatment [T2], 15.0 years; follow-up, 16.8 years), and the stable group comprised 36 subjects (11 boys, 25 girls; age at T2, 16.0 years; follow-up, 15.1 years). On cephalograms taken at T2 and T3, facial morphology was evaluated, and total posttreatment mandibular rotation was measured with a structural method. Logistic regression analyses were used to determine the association between relapse and amount of total mandibular rotation. The models were adjusted for potentially confounding variables (age at T2, sex, length of follow-up, and intercanine width change during treatment). Results No association between total posttreatment mandibular rotation and relapse was found (P = 0.515). Total mandibular rotations were comparable in the relapse and stable groups (P = 0.386). Age at T2 was found to be correlated with long-term incisor stability (P = 0.030). Sex and intercanine width change during treatment were not related to relapse (P = 0.225 and P = 0.264, respectively). Conclusions Total mandibular rotation is not associated with relapse of the mandibular incisors. Posttreatment skeletal and dental growth changes were comparable in the relapse and stable groups.

Age-Related Long-Term Posttreatment Occlusal and Arch Changes

To evaluate differences in long-term postretention changes between adolescents and adults. 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. 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. 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.

Lower lip sucking habit treated with a lip bumper appliance.

The patient was an 11-year-old girl with a lower lip sucking habit with increased overjet, maxillary generalized spacing, and mandibular incisor irregularity. Hyperactivity of the mentalis muscle and deepening of the labiomental sulcus because of the abnormal sucking habit was observed. Orthodontic treatment was started with a lip bumper appliance to break the lower lip sucking habit and continued with fixed orthodontic mechanotherapy. The lip bumper appliance therapy resulted in the elimination of the lower lip sucking habit, musculus mentalis hyperactivity, and labiomental strain in addition to a gain in arch length, improvement of the lower incisor inclinations, and overjet reduction.

Effects of posttreatment skeletal maturity measured with the cervical vertebral maturation method on incisor alignment relapse

Our aim was to test the hypothesis that relapse of incisor alignment is associated with skeletal maturity at the end of treatment, as assessed with the cervical vertebral maturation (CVM) method. This was a case-control study with information from the postretention database at the University of Washington. Mandibular incisor irregularity (II) at least 10 years out of retention (T3) was used to define the subjects (II >6 mm, relapse group) and the controls (II <3.5 mm, stable group). The following model measurements were made: II at pretreatment (T1), II at posttreatment (T2), and intercanine width at T1 and T2. On cephalograms taken T2, the CVM status was determined. Logistic regression analyses were used to determine the association between relapse and CVM status after treatment. The models were adjusted for potentially confounding variables (II at pretreatment and posttreatment, intercanine width change during treatment, sex, age at T2, and treatment alternatives). No association between CVM stage at T2 and relapse was found (P = 0.89). Both groups had similar distributions of the CVM stages (P >0.05). Pretreatment II and postretention time were found to be correlated with long-term incisor stability (P = 0.007 and 0.034, respectively). Sex was not related to relapse (P = 0.33). Maturity of craniofacial structures at the end of treatment evaluated with the CVM method is not associated with long-term stability of incisor alignment.