Normal Occlusion Group Research Articles

Three-dimensional dynamic evaluation of a posed smile in normal occlusion and Class II malocclusion

PurposeThe purpose of this study was to quantify the three-dimensional movements of the lips during a posed smile and to verify the differences in the dynamic characteristics among normal occlusion and Class II malocclusion. Materials and methodsThe subjects included 30 healthy female volunteers with normal occlusion, 23 healthy female volunteers with dentoalveolar Class II malocclusion, and 20 adult female patients with skeletal Class II malocclusion. The three-dimensional measurements of the lips during a posed smile were generated using video-based tracking with three high-speed cameras. Eight landmarks on the lips were used to track lip movement. The Scheffé method of multiple comparisons was used to identify significant differences among the normal occlusion and both Class II groups. ResultsThe lower lip point moved significantly faster and farther backward in the skeletal Class II group compared with the other groups. The upper quarter point in the skeletal Class II group in the posed smile was significantly more medial than in the other groups. The vertical movements of the cheilion point of the normal occlusion group were faster than those in the other groups. ConclusionThree-dimensional dynamic evaluation of posed smiles showed significant differences in the characteristics of lip movement between the normal occlusion and Class II subjects.

Gastric emptying rate in subjects with malocclusion examined by [13C] breath test

Masticatory function is significantly lower in individuals with malocclusion than in those with normal occlusion. Although several studies suggest that masticatory function influences gastrointestinal digestive function, the relationship between malocclusion and gastrointestinal symptoms has not been studied extensively. We hypothesised that insufficient masticatory function would increase the functional burden of the stomach and have some influence on the gastrointestinal system. The purpose of this study was to investigate masticatory function and gastric emptying rate in subjects with malocclusion. Eleven healthy dentate female volunteers and eleven female patients with maloc-clusion underwent a (13) C-acetate breath test with a liquid meal. Maximum (13) CO2 exhalation time (Tmax ) was compared statistically between both groups. Masticatory function was assessed by colour-changeable chewing gum. In addition, the frequency scale for the symptoms of gastroeso-phageal reflux disease (FSSG) and questionnaires on food intake were given to both groups. The mean Tmax of the malocclusion group was significantly longer than that of the normal occlusion group (P=0·007). Masticatory performance, measured by colour-changeable gum and questionnaires, was significantly lower in the malocclusion group than in the normal occlusion group (P=0·023, P=0·003). There was no significant difference in the FSSG results between the two groups (P=0·262). This study suggested that there was a correlation between malocclusion and gastric emptying function in women.

Anteroposterior condylar position: A comparative study between subjects with normal occlusion and patients with Class I, Class II, Division 1, and Class III malocclusions

BackgroundThe present study aimed to determine and compare the anteroposterior position of the condyle in the mandibular fossa between groups of asymptomatic subjects with normal occlusion and asymptomatic subjects with Class I, Class II Division 1, and Class III malocclusions.Material/MethodsThirty persons with normal occlusion, 30 with Class I malocclusion, 30 with Class II Division 1, and 30 with Class III had computed tomography scans of their temporomandibular joints. The anterior joint space/posterior joint space (AJS/PJS) ratio was determined for the right and left joints. The paired t test was used to analyze the AJS/PJS ratio between both sides for each group. The ANOVA test was applied to verify the differences between the groups for the measurements of the right and left sides. In case the ANOVA test confirmed significance, the Dunnett’s t test was performed to compare the groups of malocclusion with that of normal occlusion.ResultsThe paired t test between the AJS/PJS relationships in the right and left sides showed the following p values: Class I (0.168), Class II Division 1 (0.662), Class III (0.991), and normal occlusion (0.390). The ANOVA test showed a p value of 0.445 for the comparisons of the right side and 0.040 for the left side. The Dunnett’s t test demonstrated a statistically significant difference between the Class II group and the normal occlusion group (p value of 0.026) in the joints of the left side.ConclusionsBilateral symmetry and lack of condyle centralization were common characteristics among all groups. The greatest condylar decentralization was observed in the Class II group, whereas the least condylar decentralization was found in the normal occlusion group.

Comparison between dental and basal arch forms in normal occlusion and Class III malocclusions utilizing cone-beam computed tomography

ObjectiveThe purpose of this study was to investigate the relationship between the mandibular dental and basal arch forms in subjects with normal occlusion and compare them with those of Class III malocclusion using cone-beam computed tomography (CBCT).MethodsCBCT images of 32 normal occlusion (19 males, 13 females; 24.3 years) and 33 Class III malocclusion subjects (20 males, 13 females, 22.2 years) were selected. Facial axis and root center points were identified from the left to right mandibular first molars. Distances between the facial axis and root center points for each tooth were calculated, and 4 linear and 2 ratio variables were measured and calculated for each arch form. The variables were compared between groups by independent t-test. Pearson correlation coefficient was applied to assess the relationships between dental and basal variables within each group.ResultsThe mandibular dental and basal intercanine widths were significantly greater in the Class III group than in normal occlusion subjects (p < 0.05). The dental and basal intercanine widths as well as the dental and basal intermolar widths were strongly correlated in normal occlusion and moderately correlated in Class III malocclusion.ConclusionsThe dental arch form demon strated a strong positive correlation with the basal arch form in the normal occlusion group and moderate correlation in the Class III malocclusion group. These results might be helpful for clinicians to have a better understanding of the importance of basal arch form in the alveolar bone.

Effect of incisor position on the self-perceived psychosocial impacts of malocclusion among Chinese young adults

To evaluate the impact of the incisor position on the self-perceived psychosocial impacts of malocclusion among Chinese young adults. This cross-sectional study included a convenience sample of 17.1- to 22.3-year-old young adults (n = 1005). The five groups represented were normal occlusion as well as incisor Class I, Class II/1, Class II/2, and Class III malocclusion. For clinical assessment, the incisor relationship was evaluated according to the British Standards Institute Incisor Classification, and the self-perception of dental esthetics was assessed using the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ). Statistical analysis involved the analysis of variance and Tukey multiple-comparison post hoc tests. Psychosocial impacts were different among the five groups for the four PIDAQ domains (P < .001 for all four domains). Statistically significant differences were found between the four malocclusion groups and the normal occlusion group in all four domains (P < .001 for all four domains). Furthermore, statistically significant differences were found between four malocclusion groups. All four malocclusion groups had more severe psychosocial impacts than the normal occlusion group in the four PIDAQ domains. Statistically significant differences were also found between the four malocclusion groups; these malocclusion groups ranked by score, highest to lowest, were Class III, Class II/1, Class II/2, and Class I.

Mandibular dimensions of subjects with asymmetric skeletal Class III malocclusion and normal occlusion compared with cone-beam computed tomography

The purpose of this study was to use cone-beam computed tomography to compare mandibular dimensions in subjects with asymmetric skeletal Class III malocclusion and those with normal occlusion. Cone-beam computed tomography scans of 38 subjects with normal occlusion and 28 patients with facial asymmetry were evaluated and digitized with Invivo software (Anatomage, San Jose, Calif). Three midsagittal and 13 right and left measurements were taken. The paired t test was used to compare the right and left sides in each group. The Mann-Whitney U test was used to compare the midsagittal variables and the differences between the 2 sides of the group with normal occlusion with those of asymmetry patients. The posterior part of the mandibular body showed significant differences between the deviated and nondeviated sides in asymmetric Class III patients. The difference of the asymmetry group was significantly greater than that of the normal occlusion group for the mediolateral ramal and the anteroposterior condylar inclinations (P = 0.007 and P = 0.019, respectively). The asymmetric skeletal Class III group showed significant differences in condylar height, ramus height, and posterior part of the mandibular body compared with the subjects with normal occlusion. These results might be useful for diagnosis and treatment planning of asymmetric Class III patients.

A Radiographic Evaluation of Mandibular Asymmetry in Class II Division 1 Malocculsion Pattern

Introduction: Mandibular asymmetry may cause not only esthetic problem but also functional problem as it has a direct role in stomatognathic system.&#x0D; Objective: The objective of this study was to find out the difference between condylar asymmetry ratio in Class II division 1 malocclusion group and normal occlusion group in males and females.&#x0D; Materials &amp; Methods: Orthopantomogram radiographs were selected from the pool of records such that there were 40 Class II division 1 males and females above 20 years of age. Thirty normal occlusion subjects (15 males, 15 females) were enrolled and orthopantomogram records were taken. All the films were hand traced on the acetate paper and the mean condylar, ramal and condylar plus ramal asymmetry index were measured in the normal and Class II Division 1 groups according to the method given by Habets. Independent sample t-test was done to compare between the normal occlusion and Class II Division 1 malocclusion for each male and female group.&#x0D; Result: Significant difference was observed between condylar heights, combined height and condylar asymmetrical ratio. Respectively in females. However, all other asymmetrical ratios were insignificant. Similarly, for males, condylar height, ramus height, combined (condyle and ramus) were all significant respectively. However, the asymmetric ratios were found to be insignificant. There is a significant difference between Class II division 1 malocclusion and normal occlusion group in terms of condylar asymmetry ratio in female subjects. However, it was not significant in case of male subjects.&#x0D; Conclusion: Our study suggests that females with Class II division 1 malocclusion more prone to TMD in comparison to males.

Occlusal hypofunction causes periodontal atrophy and VEGF/VEGFR inhibition in tooth movement

To examine changes in microvasculature and the expression of vascular endothelial growth factor A (VEGF-A) and VEGF receptor 2 (VEGFR-2) in rat hypofunctional periodontal ligament (PDL) during experimental tooth movement. Twelve-week-old male Sprague-Dawley rats were divided into normal occlusion and occlusal hypofunction groups. After a 2-week bite-raising period, rat first molar was moved mesially using a 10-gf titanium-nickel alloy closed coil spring in both groups. On days 0, 1, 2, 3, and 7 after tooth movement, histologic changes were examined by micro-computed tomography and immunohistochemistry using CD31, VEGF-A, VEGFR-2, and the terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) method. Hypofunctional molars inclined more than normal molars and did not move notably after day 1 of tooth movement. Blood vessels increased on the tension side of the PDL in normal teeth. Immunoreactivities for VEGF-A and VEGFR-2 in normal teeth were greater than those in hypofunctional teeth during tooth movement. Compressive force rapidly caused apoptosis of the PDL and vascular endothelial cells in hypofunctional teeth, but not in normal teeth. Occlusal hypofunction induces vascular constriction through a decrease in the expression of VEGF-A and VEGFR-2, and apoptosis of the PDL and vascular cells occurs during tooth movement.

Changes in masticatory functions after surgical orthognathic treatment in patients with jaw deformities: Efficacy of masticatory exercise using chewing gum

Changes in masticatory functions after surgical orthognathic treatment were evaluated longitudinally in 47 patients in whom mandibular prognathism were surgically corrected and the efficacy of masticatory exercise for the masticatory functions was evaluated. The masticatory exercise group consisted of 34 subjects and the control group consisted of 13 subjects without masticatory exercise and the normal occlusion group consisted of 20 subjects. Masticatory exercise using chewing gum was started at 6 months after surgery and was conducted for 5min two times a day for 90 days. Masticatory efficiency was measured using ATP granules, and the number and area of occlusal contacts and maximal occlusal force were measured using a computerized system consisting of pressure sensitive sheets.The mean values of all measurements before surgery in the patients were significantly lower than those in the normal occlusion group and the values increased gradually after surgery, especially in the masticatory exercise group, but the final values were still low compared with those of the normal occlusion group. The mean of executing rates of masticatory exercise in the masticatory exercise group was 68.6%. Positive correlations were found between executing rates of masticatory exercise and improvement rates in masticatory efficiency and maximal occlusal force. We conclude that masticatory exercise using chewing gum after orthognathic surgery is effective for improving masticatory efficiency and maximal occlusal force in patients with jaw deformities.

Eysenck personality and psychosocial status of adult patients with malocclusion

Objective To evaluate the personality and psychosocial status of adult malocclusion patients through the Eysenck Personality Questionnaire (EPQ) and the Symptom Checklist 90 (SCL-90). Methods The EPQ and the SCL-90 were administered to 348 adult respondents with Angle's Class I, II, III malocclusion and normal occlusion. Personality and psychosocial traits were analyzed and compared among the groups. Results Patients in Angle's Class I, II and III groups scored lower on the EPQ-E and higher on the EPQ-N than those in the normal occlusion group, whereas patients in the Class II group scored higher on the EPQ-P. The mean scores of Class I, II and III groups were significantly higher than those of the normal group on somatization, obsessive-compulsiveness, interpersonal sensitivity, depression, anxiety, and paranoid ideation. All SCL-90 scores were significantly positively correlated with EPQ-N. Psychoticism and neuroticism scores of female respondents were higher than those of male respondents. The impact of education was greatest on the EPQ-P and the EPQ-E of adult personality, whereas the impact of deformity was greatest on the EPQ-N of adult personality. Conclusions Personality and psychosocial status show differences in adult patients with Class I, II, III malocclusion and normal occlusion and can be influenced by gender, deformity, age and education.

A cephalometric evaluation of tongue from the rest position to centric occlusion in the subjects with class II division 1 malocclusion and class I normal occlusion.

Background:One of the common types of oro-dental morphopathologic relationship is the Class II Division 1 malocclusion. Therefore, the study of tongue position in Class II Division 1 may reveal a role of the tongue in the etiology or diagnosis of malocclusion.Aims:Present study was done with the aim to evaluate the tongue position radiographically in centric occlusion and rest position in the subjects with Angle's Class 1 normal occlusion and subjects with Angle's Class II Division 1 malocclusion and to find out any differences in tongue position between Angle's Class 1 normal occlusion and Angle's Class II Division 1 malocclusion group.Materials and Methods:The present study was conducted on lateral cephalogram of 40 subjects between the age ranges of 16 to 22 years. The samples were divided into the Angle's Class 1 normal occlusion group (Group I) and the Angle's Class II Division 1 malocclusion group (Group II) with the 20 in each groups. The study involved the evaluation of tongue position at rest position and centric occlusion on the lateral head cephalogram.Results:This study for the evaluation of the tongue position from the rest position to the centric occlusion showed no statistically significant changes in both groups. However, there were greater changes in various parameters (From the rest position to the centric occlusion) in the subjects with Angle's Class II Division 1 malocclusion as compared to the subjects with the Angle's Class I normal occlusion group.Conclusion:From the present study following conclusion can be drawn: with the closure of mandible from the rest position to centric occlusion the tongue moved antero-superiorly in the tip region, superiorly in the dorsum region, and antero-superiorly in the posterior region in normal occlusion and postero-superiorly in Class II Division 1 malocclusion.

Assessment of Maximum Voluntary Bite Force in Adults with Normal Occlusion and Different Types of Malocclusions

Maximum voluntary bite force (MVBF) was assessed in adults with class I normal occlusion and compared with different malocclusions. One hundred and ten subjects in the age group of 17 to 25 years were classified into various groups. Thirty subjects with class I normal occlusion (Group A), 20 subjects with Angle's class I malocclusion (Group B), 20 subjects with skeletal class II malocclusion (Group C), 20 subjects with hypodivergent facial morphology (Group D) and 20 subjects with hyperdivergent facial morphology (Group E). MVBF was measured with a bite force meter at the first premolar and first molar region bilaterally. The values were recorded and statistically analyzed. Mean MVBF value in each of the groups in the molar and first premolar region were found to be 601.83N ± 60.80, 392N ± 31.43 (group A), 592.60N ± 37.66, 378.90N ± 23.00 (group B), 586.60N ± 49.26, 377N ± 29.38 (group C), 771.50N ± 27.24, 500.60N ± 18.25 (group D), 283.85N ± 26.41, 283.85N ± 26.41 (group E). Student paired t-test was done to analyze the difference between two groups and considered as significant at a p-value of < 0.05. Significant difference was found between group A and D and group A and E with a p-value of <0.0001. No significant difference was observed between group A and group B (p = 0.5481 and 0.1148) and group A and group C (p = 0.3551 and 0.0949). ANOVA showed that there was a significant difference among groups A, D and E. No significant difference was found among groups A, B and C. Males had a higher value than females. Sagittal morphology does not significantly affect the MVBF value whereas there is a significant correlation with vertical morphology. Assessment of maximum voluntary bite force (MVBF) is a chairside procedure to evaluate masticatory muscle activity based on which treatment planning and mechanics can be known.

Comparison of tongue postures at rest position between anterior cross-bite and normal bite

Objective To compare tongue positions at rest between normal occlusion people and patients with anterior cross-bite malocclusions,and to explore whether there is any abnormality in the tongue position of the anterior cross-bite malocclusions.Methods Twenty adults of normal bite (8 males and 12 females,with an average age of 23.8 years) and 20 adults of anterior cross-bite (1 1males and 9 females,with an average age of 24.6 years) were involved in this study.The position habits of tongue were investigated by a questionnaire.The tongue positions,which were enhanced by applying barium to tongue and palatal surface,were compared by cephalometric roentgenogram.Two groups were compared by t-test to determine the variation of anterior cross-bite. Results In normal occlusion group,the dorsum of tongues was sealed with all palatal surfaces except uvula site.In anterior cross bite group,tongues were far from palate,and were difficult to lift.The profile of tongue showed standing upright forward and up in normal occlusion group,while inclining back and low in anterior cross-bite group.The tops of tongue dorsum sites were at the border of soft and hard palate in normal occlusion group.While in anterior cross bite group,the tops of tongue dorsum sites were at the border of uvula and soft palate.In anterior cross-bite group,the tongue-to palate distance was bigger than that of normal occlusion group (P＜0.01).However,both length and height of the tongue had no significant differences between two groups (P＞0.05).Conclusions In anterior cross-bite patients,tongue positions were lower than that of normal occlusion people. Key words: Anterior cross bite; Tongue position; Rest position; Normal bite

Estudo comparativo cefalométrico dos padrões dentofaciais de indivíduos portadores de oclusão normal e de más oclusões de Angle

OBJETIVO: avaliar os padrões dentofaciais de pacientes portadores de oclusão normal e más oclusões de Angle quanto a possíveis diferenças entre as grandezas estudadas, em relação ao sexo, dentro de cada grupo e entre os grupos. MÉTODOS: a amostra constou de 200 telerradiografias cefalométricas laterais obtidas de jovens brasileiros, de ambos os sexos, na faixa etária de 11 anos e 2 meses a 19 anos e 10 meses, apresentando dentição permanente. O material foi dividido, quanto ao tipo de oclusão, em cinco grupos: um de pacientes portadores de oclusão normal, e quatro de pacientes portadores de más oclusões de Angle, sendo cada grupo dividido igualmente quanto ao sexo. Foram avaliadas grandezas cefalométricas angulares e lineares. RESULTADOS: na grande maioria das grandezas, os sexos masculino e feminino não diferiram; entre os grupos, a posição da maxila não mostrou diferença significativa, o retrognatismo mandibular foi marcante nos grupos de Classe II divisões 1ª e 2ª e foram observados alguns desequilíbrios verticais com diferenças significativas; o padrão foi hipodivergente para os grupos de oclusão normal e Classe II, divisão 2ª, e neutro para os grupos de Classe I; Classe II, divisão 1ª; e Classe III; a compensação dentoalveolar foi evidente nos grupos de Classe III e de Classe II, divisão 2ª; o grupo de oclusão normal apresentou perfil mais convexo que os padrões americanos. CONCLUSÃO: foi possível configurar, de forma geral, algumas características da morfologia facial para alguns tipos de más oclusões. Entretanto, existe a necessidade de avaliar a face individualmente, pois algumas características permeiam entre os diferentes tipos de oclusão.

Temporomandibular joint and normal occlusion: Is there anything singular about it? A computed tomographic evaluation

The purpose of this study was to investigate the condyle-fossa relationship, the position of the condyles in their respective mandibular fossae, and the dimensional and positional symmetries between the right and left condyles in a sample with normal occlusion. Thirty subjects from 15 to 32 years of age with normal occlusion had computed tomography scans of their temporomandibular joints. The images obtained from the axial slices were evaluated for possible asymmetries in size and position between the condylar processes. The images obtained from the sagittal slices were used to assess the depth of the mandibular fossa, the condyle-fossa relationship, and the centralization of the condyles in their respective mandibular fossae. Paired Student t tests were applied, and Pearson product moment correlations were determined after measurements on both sides were obtained. The largest mediolateral diameter of the mandibular condylar processes (P= 0.022) and the posterior joint spaces (P= 0.048) showed statistically significant differences between the right and left sides. Statistically significant (P<0.05) anterior positioning of the condyles (noncentralized position) was observed. No singular characteristic in the temporomandibular joints of the normal occlusion group was verified. The largest mediolateral diameter of the mandibular condylar processes and the posterior joint spaces showed statistically significant differences between the right and left sides. Evaluation of the position of the condyles in their respective mandibular fossae showed noncentralized positioning for the right and left sides.

Análise da posição rotacional do primeiro molar permanente superior na má oclusão de Classe II Divisão 1

OBJETIVO: comparar a posição rotacional do primeiro molar permanente superior entre a oclusão normal e a má oclusão de Classe II, Divisão 1, de Angle. MÉTODOS: a amostra de oclusão normal consistiu de 60 pares de modelos de pacientes com média de idade de 15,1 anos, denominada Grupo 1. A amostra de Classe II, Divisão 1, consistiu de 120 pares de modelos de gesso de pacientes não tratados, com média de idade de 15,5 anos, denominada Grupo 2. Os modelos superiores foram escaneados e a posição dos molares superiores foi avaliada por três medidas angulares e uma linear, denominadas indicadores 1, 2, 3 e 4, respectivamente. A rotação mesiopalatina dos primeiros molares superiores era evidenciada pelo aumento dos valores dos indicadores 1 e 4 e diminuição dos valores dos indicadores 2 e 3. A comparação entre os grupos foi realizada pelo teste t de Student nas medidas de distribuição normal e Mann-Whitney para distribuição anormal com intervalos de confiança de 95%. RESULTADOS: diferenças estatisticamente significativas foram encontradas entre os grupos 1 e 2, para todos os indicadores dos lados direito e esquerdo. CONCLUSÃO: concluiu-se que a má oclusão de Classe II Divisão 1 apresenta maior rotação mesiopalatina dos primeiros molares superiores.

Editor's Comment and Q&A: Tooth-wear patterns in adolescents with normal occlusion and Class II Division 2 malocclusion

<h3>Introduction</h3> In this study, we investigated tooth-wear patterns in adolescents with either normal occlusion or Class II Division 2 malocclusion. <h3>Methods</h3> The sample consisted of dental casts from 165 subjects that were divided into 2 groups: 115 normal occlusion subjects (mean age, 14.3 years) and 50 complete Class II Division 2 subjects (mean age, 13.9 years). Dental wear was assessed by using a modified version of the tooth wear index. The 2 groups were compared with the Mann-Whitney test for the frequency and severity of wear on each surface of each group of teeth. The level of statistical significance was set at 5%. <h3>Results</h3> The normal occlusion group statistically had greater tooth wear on the incisal surfaces of the maxillary lateral incisors and the incisal surfaces of the maxillary canines than did the Class II Division 2 malocclusion group. The malocclusion group showed statistically greater tooth wear on the labial surfaces of the mandibular lateral incisors, the occlusal surfaces of the maxillary premolars and first molars, the occlusal surfaces of the mandibular premolars, the palatal surfaces of the maxillary second premolars, and the buccal surfaces of the mandibular premolars and first molars than did the normal occlusion group. <h3>Conclusions</h3> Subjects with normal occlusion and those with complete Class II Division 2 malocclusions have different tooth-wear patterns. Tooth wear on the malocclusion subjects should not be considered pathologic but, rather, the consequence of different interocclusal arrangements.

Tooth-wear patterns in adolescents with normal occlusion and Class II Division 2 malocclusion

In this study, we investigated tooth-wear patterns in adolescents with either normal occlusion or Class II Division 2 malocclusion. The sample consisted of dental casts from 165 subjects that were divided into 2 groups: 115 normal occlusion subjects (mean age, 14.3 years) and 50 complete Class II Division 2 subjects (mean age, 13.9 years). Dental wear was assessed by using a modified version of the tooth wear index. The 2 groups were compared with the Mann-Whitney test for the frequency and severity of wear on each surface of each group of teeth. The level of statistical significance was set at 5%. The normal occlusion group statistically had greater tooth wear on the incisal surfaces of the maxillary lateral incisors and the incisal surfaces of the maxillary canines than did the Class II Division 2 malocclusion group. The malocclusion group showed statistically greater tooth wear on the labial surfaces of the mandibular lateral incisors, the occlusal surfaces of the maxillary premolars and first molars, the occlusal surfaces of the mandibular premolars, the palatal surfaces of the maxillary second premolars, and the buccal surfaces of the mandibular premolars and first molars than did the normal occlusion group. Subjects with normal occlusion and those with complete Class II Division 2 malocclusions have different tooth-wear patterns. Tooth wear on the malocclusion subjects should not be considered pathologic but, rather, the consequence of different interocclusal arrangements.

Tooth-wear patterns in subjects with Class II Division 1 malocclusion and normal occlusion

The aim of this study was to investigate the prevalence of tooth wear in adolescents with Class II malocclusion, compared with those with normal occlusion. The sample consisted of dental casts obtained from 310 subjects, divided into 3 groups: group 1, 110 subjects with normal occlusion (mean age, 13.51 years); group 2, 100 complete Class II Division 1 patients (mean age, 13.44 years); and group 3, 100 half-cusp Class II Division 1 patients (mean age, 13.17 years). Dental wear was assessed by using a modified version of the tooth-wear index. The 3 groups were compared by means of the Kruskal-Wallis and Dunn tests, considering the frequency and the severity of wear on each surface of each group of teeth. The level of statistical significance was set at 5%. The normal occlusion group had statistically greater tooth wear on the palatal surfaces of the maxillary central incisors and the incisal surfaces of the maxillary canines than the corresponding surfaces in both Class II malocclusion groups. The complete and half-cusp Class II Division 1 malocclusion groups had statistically greater tooth wear on the occlusal surfaces of the maxillary second premolar and first molar, the occlusal surfaces of the mandibular premolars, and the buccal surfaces of the mandibular posterior teeth compared with the normal occlusion group. The half-cusp Class II Division 1 malocclusion group had significantly greater tooth wear on the incisal surfaces of the mandibular incisors compared with the complete Class II Division 1 malocclusion group. Subjects with normal occlusion and complete or half-cusp Class II Division 1 malocclusions have different tooth-wear patterns. Tooth wear on the malocclusion subjects should not be considered pathologic but rather consequent to the different interocclusal tooth arrangement.

Editor's Summary and Q&A: Tooth-wear patterns in subjects with Class II Division 1 malocclusion and normal occlusion

Introduction The aim of this study was to investigate the prevalence of tooth wear in adolescents with Class II malocclusion, compared with those with normal occlusion. Methods The sample consisted of dental casts obtained from 310 subjects, divided into 3 groups: group 1, 110 subjects with normal occlusion (mean age, 13.51 years); group 2, 100 complete Class II Division 1 patients (mean age, 13.44 years); and group 3, 100 half-cusp Class II Division 1 patients (mean age, 13.17 years). Dental wear was assessed by using a modified version of the tooth-wear index. The 3 groups were compared by means of the Kruskal-Wallis and Dunn tests, considering the frequency and the severity of wear on each surface of each group of teeth. The level of statistical significance was set at 5%. Results The normal occlusion group had statistically greater tooth wear on the palatal surfaces of the maxillary central incisors and the incisal surfaces of the maxillary canines than the corresponding surfaces in both Class II malocclusion groups. The complete and half-cusp Class II Division 1 malocclusion groups had statistically greater tooth wear on the occlusal surfaces of the maxillary second premolar and first molar, the occlusal surfaces of the mandibular premolars, and the buccal surfaces of the mandibular posterior teeth compared with the normal occlusion group. The half-cusp Class II Division 1 malocclusion group had significantly greater tooth wear on the incisal surfaces of the mandibular incisors compared with the complete Class II Division 1 malocclusion group. Conclusions Subjects with normal occlusion and complete or half-cusp Class II Division 1 malocclusions have different tooth-wear patterns. Tooth wear on the malocclusion subjects should not be considered pathologic but, rather, consequent to the different interocclusal tooth arrangement.