Purpose
The study was aimed at evaluating the sagittal and transversal inclinations of upper second molars in untreated adolescents with normal occlusion.
Methods
A sample of 41 subjects (16 females, ...25 males) was selected from the University of Michigan Growth Study (UMGS). Digital dental casts with fully erupted second molars in occlusion were chosen (mean age 14.9 ± 1.3 years). Digital measurements were recorded with the open source software 3D Slicer (
www.slicer.org
). The digital measurements of the UMGS sample were compared with the manual measurements collected by Andrews from his sample of untreated class I subjects with normal overbite and overjet. Two mixed effect models (sagittal and transversal inclinations) were performed. The “random effect” was represented by the subjects, while the “fixed effects” were the two compared groups, the side of the arch (right and left), and the group × side interaction. Outcome variables were sagittal and transversal inclinations of the upper second molars.
Results
The UMGS group showed a significantly greater distal crown angulation (−18.9°) with respect to the Andrews sample (0.4°,
P
< 0.0001). As for the transversal inclination, the UMGS group exhibited significantly greater lingual crown inclination (−10.6° versus −8.0°,
P
= 0.0118).
Conclusions
Fully erupted maxillary second molars in a sample of adolescent subjects with normal occlusion showed significantly greater distal and lingual inclinations when compared with Andrews’ values. The finding of a distal crown inclination in contrast with Andrews’ observation of a mesial crown inclination suggests that revision in tip prescription for preadjusted brackets may be considered.
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CMK, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Objective
The aim of this study was to develop a prediction model that combines the information derived from chronological age (analysed as a curvilinear variable), gender and the CVM method to ...predict mandibular growth.
Settings and Sample Population
50 participants (29 females, 21 males) were selected from the AAOF Craniofacial Growth Legacy Collection, the Michigan Growth Study and the Denver Child Growth study.
Materials and Methods
In this investigation, 456 lateral cephalograms were analysed by applying a mixed effect model. The outcome variable was the annualized increment in total mandibular length (Co‐Gn) during the year following the lateral cephalogram on which the cervical stage and chronological age were evaluated. The predictive variables were chronological age up to the fifth order, gender, stage of cervical vertebral maturation, as well as interactions between age and gender, age and cervical stage, and gender and cervical stage.
Results
Cervical stage, chronological age up to the fourth order, gender, and the interaction between age and gender were significant predictors of annualized increments in mandibular length. The annualized increment in Co‐Gn was significantly greater for CS 3 when compared to all other cervical stages. Further, annualized increments in Co‐Gn for CS 1 and CS 2 were significantly greater when compared to CS 5.
Conclusions
Cervical stage, chronological age and gender can be used jointly to predict the annualized increment in mandibular growth. Cervical stage 3 exhibited the greatest annualized increase in mandibular length.
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CMK, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
13.
Three-dimensional mandibular dental changes with aging Garib, Daniela; Miranda, Felicia; Massaro, Camila ...
American journal of orthodontics and dentofacial orthopedics,
02/2021, Volume:
159, Issue:
2
Journal Article
Peer reviewed
Open access
This study aimed to evaluate the 3-dimensional (3D) mandibular dental changes over 42 years using the registration of digital models.
The sample comprised digital dental models of 8 untreated ...subjects (4 males and 4 females) with normal occlusion measured longitudinally at ages 17 years (T1) and 60 years (T2). Using 13 landmarks placed on the mucogingival junction, we registered the T2 model on the T1 model. Three-dimensional changes in the position of the landmarks on the buccal cusp tip of the posterior teeth and incisal edge of the central incisors were measured by 2 examiners. Registration and measurements were performed using SlicerCMF (version 3.1; http://www.slicer.org) software. Intra- and interrater agreements were evaluated using intraclass correlation coefficients and the Bland-Altman method. One-sample t tests were used for evaluating interphase 3D dental changes (P <0.05).
Adequate intra- and interrater reproducibility was found. From T1 to T2, the mandibular teeth showed significant 3D positional changes. A significant dental eruption relative to the mucogingival junction was observed for the anterior and posterior teeth. Anteroposterior movements of mandibular teeth were not significant except for the right molar that drifted mesially. Transverse movements included slight lingual tipping at canines and premolars regions.
Dental changes in untreated normal occlusion were very slight from early to mature adulthood. The eruption of the mandibular teeth was the most consistent finding. A tendency for mesial movement of molars and lingual movement of first premolars and canines was observed in the mandible during the aging process.
•We evaluated mandibular dental changes using the registration of digital models.•The sample comprised 8 normal occlusion dental models taken at ages 17 years and 60 years.•After 42 years, mandibular teeth showed small but significant 3-dimensional positional changes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
To compare the accuracy of craniometric measurements made on lateral cephalograms and on cone beam computed tomography (CBCT) images.
Ten fiducial markers were placed on known craniometric landmarks ...of 25 dry skulls with stable occlusions. CBCT scans and conventional lateral headfilms subsequently were taken of each skull. Direct craniometric measurements were compared with CBCT measurements and with cephalometric measurements using repeated measures analysis of variance (ANOVA). All measurements were repeated within a 1-month interval, and intraclass correlations were calculated.
No statistically significant difference was noted between CBCT measurements and direct craniometric measurements (mean difference, 0.1 mm). All cephalometric measurements were significantly different statistically from direct craniometric measurements (mean difference, 5 mm). Significant variations among measurements were noted. Some measurements were larger on the lateral cephalogram and some were smaller, but a pattern could be observed: midsagittal measurements were enlarged uniformly, and Co-Gn was changed only slightly; Co-A was always smaller.
CBCT craniometric measurements are accurate to a subvoxel size and potentially can be used as a quantitative orthodontic diagnostic tool. Two-dimensional cephalometric norms cannot be readily used for three-dimensional measurements because of differences in measurement accuracy between the two exams.
Summary
Objective
To evaluate the role of treatment timing on long-term dentoskeletal effects of Class II treatment with removable functional appliances followed by full-fixed appliance therapy.
...Materials and methods
A group of 46 patients (23 females and 23 males) with Class II malocclusion treated consecutively with either Bionator or Activator, followed by fixed appliances was compared with a matched control group of 31 subjects (16 females and 15 males) with untreated Class II malocclusion. The treated sample was evaluated at T1, start of treatment (mean age: 9.9 ± 1.3 years); T2, end of functional treatment and prior to fixed appliances (mean age: 11.9 ± 1.3 years); and T3, long-term observation (mean age: 18.3 ± 2.1 years). The treated and the control samples were divided into pre-pubertal and pubertal groups according to skeletal maturity observed at the start of treatment. Statistical comparisons were performed with independent sample t-tests.
Results
When treatment was initiated before puberty, Class II correction was mostly confined to the dentoalveolar changes, with significant improvements of both overjet and molar relationships. On the other hand, treatment with the outset at puberty produced significant long-term improvement of sagittal skeletal relationships, which were mainly sustained by mandibular changes.
Conclusions
Treatment with removable functional appliances (Bionator or Activator) followed by full-fixed appliances produced significant skeletal long-term changes when it begins at puberty. Prepubertal Class II treatment results primarily in dentoalveolar changes.
To determine the treatment effects produced in Class II patients by the Carriere
Motion 3D™ appliance (CMA) followed by full fixed appliances (FFA).
This retrospective study evaluated 34 adolescents ...at three time points: T1 (pretreatment), T2 (removal of CMA), and T3 (posttreatment). The comparison group comprised 22 untreated Class II subjects analyzed at T1 and T3. Serial cephalograms were traced and digitized, and 12 skeletal and 6 dentoalveolar measures were compared.
Phase I with CMA lasted 5.2 ± 2.8 months; phase II with FFA lasted 13.0 ± 4.2 months. CMA treatment restricted the forward movement of the maxilla at point A. There was minimal effect on the sagittal position of the chin at pogonion. The Wits appraisal improved toward Class I by 2.1 mm during the CMA phase but not during FFA. Lower anterior facial height increased twice as much in the treatment group as in controls. A clockwise rotation (3.9°) of the functional occlusal plane in the treatment group occurred during phase I; a substantial rebound (-3.6°) occurred during phase II. Overjet and overbite improved during treatment, as did molar relationship; the lower incisors proclined (4.2°).
The CMA appliance is an efficient and effective way of correcting Class II malocclusion. The changes were mainly dentoalveolar in nature, but some skeletal changes also occurred, particularly in the sagittal position of the maxilla and in the vertical dimension.
The aim of this systematic review of the literature was to assess the scientific evidence on the efficiency of functional appliances in enhancing mandibular growth in Class II subjects. A literature ...survey was performed by applying the Medline database (Entrez PubMed). The survey covered the period from January 1966 to January 2005 and used the medical subject headings (MeSH). The following study types that reported data on treatment effects were included: randomized clinical trials (RCTs), and prospective and retrospective longitudinal controlled clinical trials (CCTs) with untreated Class II controls. The search strategy resulted in 704 articles. After selection according to the inclusion/exclusion criteria, 22 articles qualified for the final analysis. Four RCTs and 18 CCTs were retrieved. The quality standards of these investigations ranged from low (3 studies) to medium/high (6 studies). Two-thirds of the samples in the 22 studies reported a clinically significant supplementary elongation in total mandibular length (a change greater than 2.0 mm in the treated group compared with the untreated group) as a result of overall active treatment with functional appliances. The amount of supplementary mandibular growth appears to be significantly larger if the functional treatment is performed at the pubertal peak in skeletal maturation. None of the 4 RCTs reported a clinically significant change in mandibular length induced by functional appliances; 3 of the 4 RCTs treated subjects at a prepubertal stage of skeletal maturity. The Herbst appliance showed the highest coefficient of efficiency (0.28 mm per month) followed by the Twin-block (0.23 mm per month).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The aim of this study was to test the reproducibility of three-dimensional (3D) surface models of maxillary incisors and to propose a characterization of root morphology. The sample was comprised of ...pre-treatment cone-beam computed tomography (CBCT) images of fifty-five patients. The CBCTs were used to construct 3D surface models of the maxillary incisors. The reproducibility of surface models was tested by repeated construction of them by two observers. A 3D surface model that corresponded to the average of all lateral and all central incisors was generated. 3D surface distances and vector differences were calculated for each individual tooth and the average of the teeth considered. The corresponding points on the 3D surface mesh for each subgroup were compared statistically to those of the neutral subgroup using shape analysis MANCOVA and Hotelling's t-statistic (p < 0.05). Repeated construction of surface models demonstrated adequate inter-rater reproducibility. The distribution of 3D models into root morphology subgroups was: blunt (11% and 26% of the central and lateral incisors, respectively), conical (15% of the central incisors), long (27% and 20% of the central and lateral incisors, respectively), and short (15% and 4% of the central and lateral incisors, respectively). Compared to the neutral average, statistically significant differences in root morphology were found for blunt, long, conical, and short central incisors and for blunt, long, and short lateral incisors. We can conclude that 3D surface models construction for upper incisors is reproducible. 3D shape analysis using CBCT images allows a phenotypic characterization of incisor root morphology.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Introduction: The purpose of this investigation was to evaluate craniofacial growth changes from late adolescence through late adulthood in participants from the University of Michigan Elementary and ...Secondary School Growth Study. Methods: This was a recall study with 39 subjects (19 male, 20 female). Their lateral cephalograms taken during late adolescence (T1; mean age, about 17 years), midadulthood (T2; mean age, about 47 years), and late adulthood (T3; mean age, about 57 years) were evaluated. To test for significant differences between times, sexes, and the sex and time interaction, repeated measures analysis of variance was used. For the comparisons of time (T1 vs T2, T2 vs T3), the nominal α level was set at 0.01. Results: Skeletal changes were significant only from late adolescence to midadulthood; soft-tissue changes were significant from late adolescence to midadulthood, and mid- to late adulthood. Changes in skeletal tissues consisted of increases in sella-nasion length, midfacial length, and lower anterior facial height. Sex differences were apparent in the mandible. The women had downward and backward mandibular rotation; the men, on the other hand, had more forward rotation of the mandible and increased chin prominence. Mandibular growth was greater in the men. Changes in the soft tissues were the most remarkable and included significant thinning and elongation of the upper lip. Significant changes in the nose took place, including drooping of the nasal tip and columella, the latter leading to more acute nasolabial angles. Conclusions: Our findings in this longitudinal study provide insights on several significant changes in the aging craniofacial complex.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
To analyze the long-term skeletal and dentoalveolar effects and to evaluate treatment timing of Class II treatment with functional appliances followed by fixed appliances.
A group of 40 patients (22 ...females and 18 males) with Class II malocclusion consecutively treated either with a Bionator or an Activator followed by fixed appliances was compared with a control group of 20 subjects (9 females and 11 males) with untreated Class II malocclusion. Lateral cephalograms were available at the start of treatment (mean age 10 years), end of treatment with functional appliances (mean age 12 years), and long-term observation (mean age 18.6 years). The treated sample also was divided into two groups according to skeletal maturity. The early-treatment group was composed of 20 subjects (12 females and 8 males) treated before puberty, while the late-treatment group included 20 subjects (10 females and 10 males) treated at puberty. Statistical comparisons were performed with analysis of variance followed by Tukey's post hoc tests.
Significant long-term mandibular changes (Co-Gn) in the treated group (3.6 mm over the controls) were associated with improvements in the skeletal sagittal intermaxillary relationship, overjet, and molar relationship (∼3.0-3.5 mm). Treatment during the pubertal peak was able to produce significantly greater increases in total mandibular length (4.3 mm) and mandibular ramus height (3.1 mm) associated with a significant advancement of the bony chin (3.9 mm) when compared with treatment before puberty.
Treatment of Class II malocclusion with functional appliances appears to be more effective at puberty.
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