Aging changes in maxillary anterior teeth in untreated individuals: an observational longitudinal study

OBJECTIVE

The aging of the occlusion and tooth wears influence the smile design This study aimed at evaluating the aging changes of maxillary anterior teeth in nontreated subjects.

METHODS

The sample comprised dental models of 23 subjects (13 male, 10 female) with normal occlusions, taken at 13 (T1), 17 (T2) and 61 (T3) years of age. The following variables were measured in the maxillary anterior teeth using digital dental models: crown width/height proportion, anterior view width, crown angulation, gingival and incisal steps between central/lateral incisors and central incisors/canines. Interphase comparisons were evaluated using repeated measures analysis of variance followed by Tukey tests or Friedman tests. Sexual differences were evaluated using t tests (P < 0.05).

RESULTS

From 13 to 61 years of age, a decrease of crown width/height proportion (P = 0.008 and P =  < 0.001, for the lateral incisor and canines, respectively) and mesiodistal angulation (P =  < 0.001, P = 0.001 and P = 0.025 for the central incisor, lateral incisor and canines, respectively) of the maxillary anterior teeth were observed. The steps of the gingival margin and the incisal steps decreased with aging.

CONCLUSIONS

From adolescence to late adulthood, untreated individuals with normal occlusions demonstrated changes in the maxillary anterior teeth that may impair the smile esthetics and attractiveness.

Dehiscence and fenestration of Class I individuals with normality patterns in the anterior region: a CBCT study

OBJECTIVES

The purpose of this study was to investigate the prevalence of alveolar bone dehiscence and fenestration of Class I individuals with normality patterns in the anterior region using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

A total of 4715 retrospective cases from January 2018 to December 2020 in the Orthodontic Department of xxx Hospital were screened. Sixty-one cases were Class I individuals with normality patterns in the anterior region. Their incidence of dehiscence and fenestration in the anterior teeth region was studied and statistically analyzed.

RESULTS

Dehiscence was found in 27.46% of the evaluated anterior teeth and fenestration was found in 26.91% of anterior teeth. Severe dehiscences and fenestrations mainly occurred in mandibular canines and maxillary canines, respectively. Alveolar bone defects were present in 100% of patients, while one patient had alveolar bone defects in 91.67% of the anterior teeth.

CONCLUSIONS

Dehiscence was found in 27.46% of the anterior teeth of Class I individuals with normality patterns, while fenestration was found in 26.91% of them. Alveolar bone defects were present in 100% of patients.

CLINICAL RELEVANCE

Alveolar bone dehiscence and fenestration were normal and common in our sample, indicating that they are more likely to be physiological rather than pathological defects. Orthodontists should be aware of the presence and severity of these defects before treatment in order to avoid both possible complications and overtreatment.

Malocclusion and occlusal traits among dental and nursing students of Seven North-East states of India

BACKGROUND

Any irregularity of the teeth or a mal-relationship of the dental arches is known as malocclusion. Among all the oro-facial problems, tooth decay is considered the most prevalent one followed by periodontal disease and dental malocclusion. Dental malocclusion is not a life-threatening condition. However, it is closely related to an individual's self-esteem and psychosocial wellbeing. The prevalence of malocclusion varies among different ethnic groups, age-groups, and gender.

OBJECTIVES

This study was conducted with the objective to find out the prevalence of normal occlusal traits and to identify the proportion of different types of malocclusions among dental and nursing students of Seven North-Eastern states studying at a tertiary care Medical Institute.

METHODS AND MATERIALS

This cross-sectional study included 432 students with a mean age of 21.42 years, who satisfied the inclusion criteria. Inclusion criteria consisted of the presence of all permanent teeth with or without third molars. The oral cavity was examined using a sterile mouth mirror and flashlight followed by evaluation of all the occlusal relationships in centric occlusion position (COP). COP was achieved by asking the participant to swallow, and then to bite on his or her teeth together. The occlusion traits were assessed as normal occlusion or malocclusion using the first permanent molars as described by E.H. Angle and deviation from line of occlusion. Descriptive statistics like mean and proportions were calculated.

RESULTS

The prevalence of normal occlusal traits was 48.4%, and that of malocclusion was 51.6%. Class I malocclusion was most prevalent occlusal trait followed by Class II malocclusion and Class III malocclusion showed the least prevalence.

CONCLUSIONS

Class I malocclusion was most prevalent followed by Class II malocclusion and Class III malocclusion showed the least prevalence.

Effectiveness of modifications to preadjusted appliance prescriptions based on racial dental characteristics assessed by the ABO Cast-Radiograph Evaluation: A propensity score matching study

Background

Because racial discrepancies in dental characteristics are known to exist, designing preadjusted appliances according to racial normal occlusion data would be expected to improve treatment results. However, whether modifications based on racial characteristics can improve treatment outcomes in the clinic remains to be investigated.

Methods

To study the influence of prescription type on treatment outcomes, 91 patients treated with Chinese or Roth prescription appliances were selected as an initial sample. Two groups of patients were selected by propensity score matching (1:1) to limit the effects of confounding factors, including age, sex, case complexity, and extraction plan. Discrepancy Index and cervical vertebral maturation values were used to quantify case complexity and patient age, respectively. After matching, the final sample of 60 patients consisted of two groups of 30 patients each: group 1 had been treated with a Chinese prescription appliance and group 2 had been treated with a Roth prescription appliance. ABO casts and radiograph evaluation (CR-Eval) and lateral cephalograms were utilized to compare the treatment outcomes of the two groups.

Results

The total ABO scores of groups 1 and 2 were 22.03 and 23.87, respectively. There were no significant differences between the two groups in total ABO score or in seven other sub-scores; however, there was a significant difference between the two groups in mandibular canine alignment score.

Conclusions

There are no significant differences in overall treatment outcomes between the Chinese and Roth prescription appliances. The Chinese prescription yielded better alignment results in the mandibular canine for Chinese patients.

Comparison of Tooth Widths, Arch Widths and Arch Lengths in Class-I Normal Dentition to Class-I and II Crowded Dentitions

Background and Objective:

Dental study casts play a vital role in the diagnosis and treatment planning of various orthodontic cases. This study was carried out to compare the tooth widths, arch widths, and arch lengths in Class-I normal dentition to those in Class-I and Class-II crowded dentition in an effort to improve treatment planning and to eventually reduce treatment duration.

Methods:

Total 170 patients, 12 to 40 years of age with a complete set of permanent teeth till 1^st molars; who presented to the Orthodontics Department at Armed Forces Institute of Dentistry (A.F.I.D), Rawalpindi from Sep 2019 to Feb 2020, were included in the study. Non-probability purposive method of sampling was used. The dental casts obtained were used to measure tooth widths, arch widths, and arch lengths. Subjects were classified into Class-I normal and Class-I and Class-II crowded occlusion and comparison of the sum of tooth widths, arch widths, and arch length discrepancies were determined among the three occlusion groups. Data was analyzed in SPSS version 21 and independent samples t-test was used to differentiate the variables of interest.

Results:

Out of 170 subjects, 73 (42.9%) subjects had Class-I normal occlusion while 97 (57%) had Class-I and Class-II crowded occlusions. No statistical difference was found between the occlusal groups with regard to the sum of tooth widths, inter-canine widths, inter-first premolar widths, inter-second premolar widths and inter-molar widths. However, a remarkable difference was observed between the occlusal groups with respect to arch perimeters and arch length discrepancies (p = 0.000 and 0.000 respectively).

Conclusions:

Results of the current study indicate that crowding of teeth occurs as a consequence of decreased arch perimeters which may lead to increased arch length discrepancies. However, no prominent difference was noticed in the sum of tooth widths and arch widths among different occlusal groups.

Correlation between mandibular morphology and masticatory muscle thickness in normal occlusion and mandibular prognathism

OBJECTIVES

: The aim of this study was to evaluate the relationship between masticatory muscle thickness and mandibular morphology in young Korean adults with normal occlusion and mandibular prognathism.

PATIENTS AND METHODS

Multidetector computed tomography (MDCT) was used to measure the masticatory muscle thickness on the right side in 100 Korean young adults (50 normal occlusion group, 50 mandibular prognathism group). Cephalometric analysis was done to measure mandibular morphology. Pearson correlation analysis was done to investigate the relationship between the masticatory muscle thickness and mandibular morphometry.

RESULTS

The four masticatory muscles showed positive correlation with intergonial width in all subjects. All muscles, except temporalis, positively correlated with height of the ramus and mandibular length. Positive correlation was also observed in all muscles, except medial pterygoid, with thickness of the ramus. In the normal occlusion group, all four masticatory muscles showed positive correlation with intergonial width and ramus thickness. Positive correlation was also observed in all muscles (except lateral pterygoid) with mandibular length. Masseter and lateral pterygoid positively correlated with height of the ramus. In the mandibular prognathism group, all masticatory muscles, except lateral pterygoid, showed positive correlation with intergonial width. The masseter muscle showed negative correlation with ANB.

CONCLUSION

The results suggest a positive correlation of the thickness of masticatory muscles with both horizontal and vertical dimensions of the mandible. However, thickness of the masseter was found to decrease in patients with increasing severity of mandibular prognathism.

Three-dimensional analysis of temporomandibular joint in Chinese adults with normal occlusion and harmonious skeleton

OBJECTIVE

This study aimed to analyze the detailed three-dimensional measurements of temporomandibular joint (TMJ) in Chinese adults with normal occlusion and harmonious skeleton.

METHODOLOGY

In 51 subjects 102 joints were analyzed using Anatomage Invivo dental 5.4. The measurements include: joints' parameters, position, angulation, and inclination of the condyle and articular fossa as well as 3D volumetric of the joint-spaces. All measurements were statistically analyzed by paired Student's t test to find out the differences between the left- and right sides. Pearson correlation coefficient test was done to figure out the relationship of the TMJ parts in the normal situation.

RESULTS

The inter-condyle distances medially, geometrically, and laterally were 90.2 ± 5.2,107 ± 6.1, and 125 ± 5.5 mm, respectively. However, the 102 condyles were angulated on three planes 54.9º ± 11.2, 71.8º ± 7.3, and 12.5º ± 6.3 at vertical-, horizontal-, and midsagittal planes, respectively. The joint spaces measurements were 2.6 ± 0.7 mm, 2.5 ± 0.8 mm, 2.4 ± 0.7 mm, and 3.3 ± 0.7 mm for anterior-, medial-, posterior-, and superior joints, respectively. The total volume of the whole joint-space was 404.3 ± 71mm³. The left condyle position was on the centric position whereas the right condyle was eccentric (slightly anterior).

CONCLUSION

Chinese subjects are characterized by wide inter-fossa distance and inter-condyle distance; however, no significant correlations with joint spaces in normal occlusion were found. The asymmetries between right- and left mandibular condyle were distinguished in angular and linear-vertical measurements. Finally, this study could be considered as reference data for upcoming research in the Chinese population.

Comparison of dental and alveolar arch forms between different ethnic groups

OBJECTIVE

The aims of this study were to evaluate, by means of 3D software, any correlation between ethnic group and the shape and size of the dental arcade and its bony support, and to investigate the correspondence between the latter two variables within each ethnic group. The data gathered were also compared with the measurements of commercially available pre-formed archwires to determine which provide the best fit for each arch in each group.

MATERIALS AND METHODS

The shape and size of the dental and alveolar arches of 29 subjects of African origin and 37 Caucasian subjects were compared in terms of linear inter-canine, inter-premolar and inter-molar measurements, overall arch length, and the distance between each tooth and the reference occlusal plane. To determine which pre-formed archwires are best suited to each of the two ethnic groups, the in-out of the brackets was considered, simulating their presence in the oral cavity.

RESULTS

The upper and lower dental and alveolar arches were all wider and longer in African with respect to Caucasian subjects (P<0.05). In general, "Roth small" (index value 1.556) and "Ideal Form Medium" (index value 0.645) archwires were better suited to both upper and lower arcades in the latter group, while "Damon" (index value 1.447) and "Ideal Form Large" (index value 1.695) conformed better to the size and shape of both arcades in the former.

CONCLUSIONS

There are very significant differences in arch form between the two ethnic groups considered, and the range of pre-formed archwires on the market does not provide for the anatomical variability of patients.

New classification of lingual arch form in normal occlusion using three dimensional virtual models

Objective

The purposes of this study were 1) to classify lingual dental arch form types based on the lingual bracket points and 2) to provide a new lingual arch form template based on this classification for clinical application through the analysis of three-dimensional virtual models of normal occlusion sample.

Methods

Maxillary and mandibular casts of 115 young adults with normal occlusion were scanned in their occluded positions and lingual bracket points were digitized on the virtual models by using Rapidform 2006 software. Sixty-eight cases (dataset 1) were used in K-means cluster analysis to classify arch forms with intercanine, interpremolar and intermolar widths and width/depth ratios as determinants. The best-fit curves of the mean arch forms were generated. The remaining cases (dataset 2) were mapped into the obtained clusters and a multivariate test was performed to assess the differences between the clusters.

Results

Four-cluster classification demonstrated maximum intercluster distance. Wide, narrow, tapering, and ovoid types were described according to the intercanine and intermolar widths and their best-fit curves were depicted. No significant differences in arch depths existed among the clusters. Strong to moderate correlations were found between maxillary and mandibular arch widths.

Conclusions

Lingual arch forms have been classified into 4 types based on their anterior and posterior dimensions. A template of the 4 arch forms has been depicted. Three-dimensional analysis of the lingual bracket points provides more accurate identification of arch form and, consequently, archwire selection.

Mandibular growth comparisons of Class I and Class II division 1 skeletofacial patterns

OBJECTIVE

To determine class and sex differences in mandibular growth and modeling.

MATERIALS AND METHODS

A mixed-longitudinal sample of 130 untreated French-Canadian adolescents, 77 (45 boys and 32 girls) with Class I (normal or abnormal) occlusion and 53 (26 boys and 27 girls) with Class II division 1 malocclusion, was used. Based on eight landmarks, eight traditional measurements were used to compare the anteroposterior position of the maxilla and mandible, relationship between the jaws, and mandibular size. Mandibular superimpositions were used to compare the horizontal and vertical changes of condylion, gonion, and menton.

RESULTS

While there were no differences in maxillary position based on the SNA angle, Class IIs had more retrognathic mandibles than did Class Is. Total mandibular length was greater in Class Is than in Class IIs at 15 years of age. Superior and total growth and modeling changes at condylion and gonion, respectively, were greater for Class Is than Class IIs. Boys were more prognathic than girls; they had larger mandibles and exhibited greater size increases and growth changes than girls did.

CONCLUSIONS

There are both class and sex differences in mandibular growth and modeling.

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

OBJECTIVE

The 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).

METHODS

CBCT 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.

RESULTS

The 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.

CONCLUSIONS

The 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.