New perspective for evaluation of tooth widths in patients with missing or peg-shaped maxillary lateral incisors: Quadrant analysis

The aesthetic perception of orthodontic specialists, general dentists and laypeople regarding different smile displays for a patient missing one upper lateral incisor and the other one peg-shaped

Background

The prevalence of maxillary lateral incisor agenesis ranges from 1% to 3%, with slight global variability. The unilateral agenesis of the maxillary lateral incisor is often associated with a contralateral tooth with microdontia or a peg shape and can have esthetic, functional, and psychosocial implications for patients. The aim of the present survey was to assess the perceptions of smile aesthetics among orthodontists, general dentists and laypeople on different treatment choices, modifying the initial condition of the right maxillary lateral incisor agenesis and the contralateral peg-shaped tooth.

Methods

A series of 6 photographs of different smile simulations were presented to 109 orthodontic specialists, 109 general dentists and 141 laypeople through an online survey. Each photograph was duplicated and judged from 1 to 10 for 2 different bipolar adjectives.

Results

Statistically significant results were found for all the groups investigated. All three groups preferred the photo that maintained the typical symmetrical 'high-low-high gingival contour. Moreover, both orthodontic specialists and general dentists preferred unilateral mesialization of the canine and conservative rehabilitation of the peg-shaped incisor. In contrast, the laypeople preferred bilateral mesialization of the canines with peg-shaped incisor avulsion.

Conclusion

The normal symmetrical array of the central incisor, lateral incisor and canine had the best aesthetic results for all subjects. Laypeople were more attracted to a symmetrical smile than were the groups of orthodontic specialists and general dentists.

Buccolingual inclination of posterior dentition in maxillary impacted canine patients using quadrant analysis - A cone-beam computed tomographic study

BACKGROUND

To examine the buccolingual inclination of maxillary posterior teeth, curve of Wilson, and transversal dimensions in palatally impacted maxillary canine patients, compared to controls by cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Pre-treatment images of 22 bilateral, 32 unilateral impacted maxillary canine patients and 30 controls were included. All patients had palatally impacted canines, with no posterior cross-bite. Data were reclassified in quadrants according to the presence of impaction, as the impaction quadrant (right and left quadrants of 22 bilateral impacted cases, and quadrants presenting impaction of 32 unilateral cases, n = 76), unaffected quadrant (quadrant without impaction in 32 unilateral cases, n = 32) and the control quadrant (right and left quadrants of 30 controls, n = 60) to evaluate the buccolingual inclination angle, transversal width, and arch perimeter. Additionally, comparisons were made regarding curve of Wilson and total arch perimeter among bilateral and unilateral impaction groups with the control group. Statistical analysis was performed by one-way ANOVA and Kruskal Wallis tests. Tukey or Dunn tests were used for comparisons between groups in pairs.

RESULTS

No significant difference was found for the buccolingual inclination of maxillary posterior teeth and curve of Wilson among groups. The buccolingual inclination of canines in the impaction quadrant was significantly lower than the other quadrants (p < 0.001). Basal bone width at the level of second premolars, and alveolar width at both premolars were significantly narrower in the impaction quadrant than in the unaffected quadrant (p < 0.05). Dental arch width at the level of first premolar was significantly decreased in the impaction quadrant compared to other quadrants (p < 0.05). Arch perimeter was significantly reduced in the impaction quadrant than in the unaffected quadrant (p < 0.05).

CONCLUSION

The presence of bilateral or unilateral palatally impacted maxillary canines did not effect the buccolingual inclination of posterior teeth, and curve of Wilson. Transverse discrepancy was evident in the impaction quadrant even in the absence of posterior cross-bite. Quadrant analysis was particularly useful in evaluating asymmetry for basal bone and alveolar bone widths in the premolar region in patients with unilateral palatally impacted maxillary canine patients.

Patterns of nonsyndromic tooth agenesis and sexual dimorphism

BACKGROUND

Sex dimorphism has been implicated in oral health differences and the pathogenesis of oral diseases, such as tooth agenesis, periodontal disease, dental caries, and tooth loss. Tooth agenesis (TA) is one of the most common developmental anomalies in humans, and its prevalence and patterns are different across ethnic groups. The aim of this study was to investigate the phenotypes and sex-associated patterns of nonsyndromic tooth agenesis (TA) in Thai dental patients.

METHODS

One thousand ninety panoramic radiographs were examined. One hundred and one subjects (37 males, 64 females, 15-20 years-old) with nonsyndromic TA were evaluated. Differences in TA prevalence between groups were analyzed using the chi-square or Fisher exact test.

RESULTS

The TA prevalence, excluding third molars, was 9.3% and more frequently found in the mandible compared with the maxilla. The maxilla demonstrated a higher prevalence of first premolar agenesis than the mandible (P = 0.012), while the mandible had a higher prevalence of second premolar agenesis than the maxilla (P = 0.031). There were significantly more males missing one tooth than females, however, there were more females missing two or more teeth than males (P = 0.042). A missing maxillary left lateral incisor was significantly more frequent in males (P = 0.019), while a missing mandibular right lateral incisor was more frequent in females (P = 0.025). In females, the pattern of two mandibular lateral incisors agenesis was the most common and significantly present in females more than males (P = 0.015). In contrast, the pattern of one mandibular left lateral incisor agenesis was only observed in males and significantly found in males more than females (P = 0.047).

CONCLUSIONS

We demonstrate sex-associated differences in nonsyndromic tooth agenesis. The prevalence of single tooth agenesis was higher in males, while that of two or more teeth agenesis was higher in females. We found different patterns of lateral incisor agenesis between males and females.

Three-dimensional digital evaluation of tooth symmetry and volume in patients with missing and peg-shaped maxillary lateral incisors

INTRODUCTION

This study aimed to evaluate the 3-dimensional tooth crown symmetry and the crown volumes of maxillary and mandibular teeth in patients with unilateral or bilateral missing or peg-shaped maxillary lateral incisors.

METHODS

Six groups were established for the possible clinical variations in patients with unilateral missing or peg-shaped maxillary lateral incisors, bilateral presence of these tooth anomalies, and a control group (CG) with normal lateral incisors. The study was conducted on digital dental models of 132 patients. The morphologic symmetry of the antimere teeth was investigated using 3-dimensional deviation analysis. Volumes of contralateral teeth were compared within and among groups for the maxilla and mandible. Furthermore, volumes of teeth were compared in missing and peg-shaped quadrants and quadrants of CG. Intergroup differences were tested using one-way analysis of variance and Kruskal-Wallis tests, whereas paired t and Wilcoxon tests were used for parametric and nonparametric variables, respectively, for intragroup comparisons.

RESULTS

Significant deviations in symmetry of antimere teeth were not detected (P >0.05). The volumes of mandibular central and lateral incisors in missing or peg-shaped lateral incisor groups were smaller than in the CG (P <0.05). Per quadrant analysis, volumes of the maxillary central incisor and mandibular central incisors, canines, and first molars in quadrants with missing or peg-shaped lateral incisors were smaller than in the control quadrants (P <0.05).

CONCLUSIONS

Neither unilateral nor bilateral presence of missing or peg-shaped maxillary lateral incisors affected the morphologic symmetry of antimere teeth but did affect tooth volume, especially in the mandibular arch.

Esthetic and functional rehabilitation of peg-shaped maxillary lateral incisors: Practical recommendations

Peg-shaped maxillary lateral incisors cause many functional and esthetic major consequences in affected patients. Their esthetic and functional rehabilitations are often multidisciplinary, involving different clinical procedures like periodontal, orthodontic, or prosthodontic procedures. No exhaustive protocol has been established to improve their comprehensive management by general dentists or specialists. The aim of this article is to elaborate a simplified clinical protocol of complete management of peg-shaped maxillary lateral incisors by a multidisciplinary team (general practitioners, orthodontists, and prosthodontists). A clinical case of two peg-shaped maxillary lateral incisors completely rehabilitated with multidisciplinary approaches including orthodontic treatment and restoration by veneers and direct composite resin, according to the established protocol. Extraoral, intraoral, and smile clinical analysis are crucial to ensure optimal rehabilitation. Treatment results previsualization via wax-up and/or mock-up play a key role in the communication between practitioner and patient to help the latter make decision. These options also facilitate the achievement of a multidisciplinary approach by accurately estimating the number of dental movements and the type of restorations that are most suitable to the presenting clinical situation.

Symmetry of crown widths in subjects with unilateral maxillary lateral incisor agenesis

PURPOSE

The aim of this study was to compare mesiodistal width and symmetry of maxillary and mandibular teeth in subjects with and without unilateral maxillary lateral incisor agenesis.

PATIENTS AND METHODS

The study group consisted of 31 patients with unilateral maxillary lateral incisor agenesis (19 females, 12 males, mean age: 16.55 ± 5.24 years), and a control group of 31 patients (19 females, 12 males, mean age: 16.58 ± 4.41 years) without agenesis. Mesiodistal dimensions of all teeth except second molars were measured. Paired samples t‑test and Wilcoxon signed-rank test were used for intragroup comparisons. Independent samples t‑test was used for intergroup comparisons.

RESULTS

In the study group, mesiodistal dimensions of maxillary canine, second premolar, first molar, mandibular second premolar and first molar teeth on the agenesis side were significantly smaller than on the contralateral side (p < 0.05). In the control group, no significant difference was seen in mesiodistal dimensions between right and left sides. In the study group, mesiodistal dimensions of all teeth on the lateral agenesis side were significantly smaller than on the control side (p < 0.05). On the side without lateral agenesis, all teeth except the maxillary and mandibular first molars and mandibular second premolar teeth were significantly smaller than on the control side (p < 0.05). Total mesiodistal dimensions of the maxillary teeth were significantly smaller on the lateral agenesis side than on the contralateral side (p = 0.001). Total tooth size of the study group was significantly smaller than for the control group (p < 0.05).

CONCLUSION

Patients with unilateral maxillary lateral incisor agenesis might have asymmetries in tooth width and have smaller teeth than individuals without agenesis.

Influence of maxillary lateral incisor width ratio on perception of smile esthetics among orthodontists and laypersons

OBJECTIVE

This study aimed to analyze the impact of different maxillary lateral incisor width ratios on the perception of smile esthetics among orthodontists and laypersons.

METHODS

A smile photograph of a male subject showing the lips and gingival margins was selected. The smile was standardized for maxillary central incisor width proportions and ideally perceived smile esthetics. The maxillary lateral incisor width was symmetrically modified in increments of ratios of the central incisor from a ratio of 4:10 to a ratio of 8:10. The images were analyzed by 283 laypersons and 83 orthodontists who ranked the level of attractiveness using a visual analog scale.

RESULTS

There were significant differences between the esthetic perception of the five different width ratios, and between the orthodontists and laypersons in their evaluations of esthetics (P < 0.0004). There were no significant differences in esthetic evaluations between genders.

CONCLUSIONS

For orthodontists, the most attractive width ratio was 5.7:10, while the highest ranked ratio among laypersons was 8:10, although laypersons ranked all ratios very similarly. Both groups ranked the width ratio of 4:10 the lowest. Orthodontists were more critical in their assessment of esthetics.

CLINICAL SIGNIFICANCE

To what proportions or protocol should a peg-shaped maxillary lateral incisor or missing lateral, that is, to be replaced with an implant/crown be restored? This is an important clinical question that is often encountered by the orthodontist and the restoring dentist. The literature suggests that orthodontists and laypeople have different perceptions of smile esthetics, and it is important to have patient centered goals when treatment planning. Further research is necessary to identify the width ratio of which the lateral incisor is perceived to be esthetic as well as the ideal ratio to consider when restoring lateral incisors. This research assessed and compared the perception that orthodontists and laypeople have on smile esthetics regarding different width ratios of lateral incisors.