Gingival recession in mandibular incisors and symphysis morphology-a retrospective cohort study

Local factors relating to mandibular canine impaction: A retrospective study

INTRODUCTION

This study aimed to investigate the characteristics of impacted and transmigrated mandibular canines and the association existing between them and some local factors, such as degrees of axial inclination of mandibular incisors, skeletal Class, and mandibular symphysis width.

METHODS

A retrospective observational study was performed on the medical records and radiographic examination (panoramic radiographs and lateral cephalograms) of 102 orthodontic patients divided into a study group, with at least 1 impacted mandibular canine (51 subjects) and a control group, without mandibular impaction (51 subjects). A chi-square test, t test, and analysis of variance test analysis were used to analyze the data.

RESULTS

Unilateral and buccal impaction and the presence of the deciduous canine were the more prevalent characteristics of impacted canines, whereas 39.2% presented transmigration. Furthermore, the persistence of the deciduous canine on the impaction side (P <0.0001) and the mesial axial inclination of the impacted canine (P <0.0001) were found to be statistically significant characteristics. A statistically significant association was found between the impaction of the mandibular canine and mandibular incisor to the mandibular plane angle (IMPA) (IMPA, 95.8°; P = 0.009). An additional statistically significant association was found with transmigrated canines (IMPA, 96.8°; P = 0.024).

CONCLUSIONS

The mesialization of the canine cusp and the persistence of the mandibular deciduous canine are characteristics frequently found in the impaction of the mandibular canine. An accentuated vestibular inclination of the mandibular incisors is significantly associated with mandibular canine impaction.

Comprehensive Deciphering the Complexity of the Deep Bite: Insight from Animal Model to Human Subjects

Deep bite is a malocclusion phenotype, defined as the misalignment in the vertical dimension of teeth and jaws and characterized by excessive overlap of the upper front teeth over the lower front teeth. Numerous factors, including genetics, environmental factors, and behavioral ones, might contribute to deep bite. In this study, we discuss the current clinical treatment strategies for deep bite, summarize the already published findings of genetic analysis associated with this complex phenotype, and their constraints. Finally, we propose a comprehensive roadmap to facilitate investigations for determining the genetic bases of this complex phenotype development. Initially, human deep bite phenotype, genetics of human deep bite, the prevalence of human deep bite, diagnosis, and treatment of human deep bite were the search terms for published publications. Here, we discuss these findings and their limitations and our view on future strategies for studying the genetic bases of this complex phenotype. New preventative and treatment methods for this widespread dental issue can be developed with the help of an understanding of the genetic and epigenetic variables that influence malocclusion. Additionally, malocclusion treatment may benefit from technological developments like 3D printing and computer-aided design and manufacture (CAD/CAM). These technologies enable the development of personalized surgical and orthodontic guidelines, enhancing the accuracy and effectiveness of treatment. Overall, the most significant results for the patient can only be achieved with a customized treatment plan created by an experienced orthodontic professional. To design a plan that meets the patient's specific requirements and expectations, open communication between the patient and the orthodontist is essential. Here, we propose to conduct a genome-wide association study (GWAS), RNAseq analysis, integrating GWAS and expression quantitative trait loci (eQTL), micro and small RNA, and long noncoding RNA analysis in tissues associated with deep bite malocclusion in human, and complement it by the same approaches in the collaborative cross (CC) mouse model which offer a novel platform for identifying genetic factors as a cause of deep bite in mice, and subsequently can then be translated to humans. An additional direct outcome of this study is discovering novel genetic elements to advance our knowledge of how this malocclusion phenotype develops and open the venue for early identification of patients carrying the susceptible genetic factors so that we can offer early prevention and treatment strategies, a step towards applying a personalized medicine approach.

Risk factors for gingival recessions after orthodontic treatment: a systematic review

BACKGROUND/OBJECTIVES

To systematically review the available evidence concerning the risk factors for gingival recessions (GR) after orthodontic treatment (OT).

DATA COLLECTION AND ANALYSIS

Data was obtained and collected by systematically searching 3 data bases: Pubmed, EMBASE, and Web of Science until 20 April 2023. Controlled trials, cohort, case-control or cross-sectional studies describing GR or clinical crown height (CCH) after OT were included. The risk of bias in the selected studies was evaluated with the methodological index for non-randomized studies.

RESULTS

Forty-eight articles were included, investigating the following six risk factors for GR: 1. OT (n = 21), 2. Type of orthodontic intervention (n = 32), 3. Patient's baseline occlusal and skeletal characteristics (n = 14), 4. Mucogingival characteristics (n = 10), 5. Oral hygiene (n = 9), and 6. Others (n = 12). Significantly higher prevalence, severity and extent of GR were found in orthodontic patients by 10/15, 4/10, and 2/2 articles respectively. 10/16 articles reported significantly more GR and increased CCH in patients where orthodontic incisor proclination was performed. The evidence surrounding maxillary expansion and orthodontic retention was too heterogeneous to allow for? definitive conclusions. Pre-treatment angle classification, ANB, overjet, overbite, arch width and mandibular divergence were found not to be associated with GR (9/14), while pre-treatment crossbite, symphysis height and width were (5/7 studies). A thin gingival biotype, presence of previous GR, baseline width of keratinized gingiva and facial gingival margin thickness were correlated with increased risk of GR after OT by nine articles, while pocket depth was not. Oral hygiene, sex, treatment duration, and oral piercings were found not to be linked with GR in orthodontic patients, while GR was reported to increase with age in orthodontic patients by 50 per cent of the articles investigating this factor. The mean risk of bias for comparative and not comparative studies was 14.17/24 and 9.12/16.

LIMITATIONS

The selected studies were quite heterogeneous regarding study settings, variables reported and included very limited sample sizes.

CONCLUSION

Although studies regarding the risk factors for GR are relatively abundant, they are very heterogeneous concerning design, studied factors, methodology and reporting, which often leads to contradictory results. Uniform reporting guidelines are urgently needed for future research.

PROSPERO REGISTRATION

CRD42020181661.

FUNDING

This research received no funding.

Lower incisor inclination and thickness of the alveolar process and mandibular symphysis in the development of gingival recession: A retrospective cohort study

Introduction

Retrospective studies have found conflicting results regarding the relationship between lower incisor inclination and the development of gingival recession (GR) after orthodontic treatment.

Objective

This study aimed to investigate the relationship between lower incisor inclination and alveolar process (AP) and mandibular symphysis (MS) thickness in the development of GR.

Materials and Methods

Frontal intraoral photography and cephalometric radiography were conducted before (T0) and after (T1) orthodontic treatment of 62 subjects. The presence of GR was considered when the cementoenamel junction was visible in the lower incisor on the frontal intraoral photograph. The circumstances for improvement, stability, and worsening of the gingival situation were based on the reduction, maintenance, and increase in the number of lower incisors with GR before and after treatment. To measure the incisor-mandibular plane angle (IMPA) and the thickness of the AP and the MS were used the cephalometric radiographs.

Results

Men had a significantly thicker MS than women at T0 and T1 (p < 0.0004). There was a significant reduction of approximately 10% in AP between T0 and T1 (p < 0.0001). Among subjects without GR at T0, 70.4% presented a stable gingival situation at T1. For subjects with 1 lower incisor with GR at T0, 50% showed improvement in the gingival situation at T1, 21.4% remained stable, and 28.6% experienced worsening. Sixteen lateral incisors presented a worsening gingival situation, representing an increase of 129% compared to the central incisors.

Conclusion

No relationship was found between lower incisor inclination and the thickness of the AP and MS in the development of GR.

Periodontal health of unilateral labially vs. palatally impacted maxillary canines erupted by closed eruption technique

OBJECTIVE

This study's aim was to compare the periodontal health of labially and palatally impacted maxillary canines erupted by closed eruption technique, and to compare them with the contralateral canines that served as control teeth.

MATERIALS AND METHODS

A total of 32 subjects, 17 with unilateral labially impacted maxillary canines and 15 with palatally impacted maxillary canines were enrolled in this study. Pretreatment maxillary canine variables were evaluated from initial panoramic radiographs using Nolla stage, α‑angle, d‑depth and s‑sector. The closed eruption technique was used for surgical exposure of the impacted teeth. Posttreatment periodontal parameters such as plaque index (PI), gingival index (GI), gingival bleeding index (GBI), probing depth (PD), keratinized gingival width (KGW), attached gingival width (AGW), and gingival thickness (GT) were evaluated to compare the periodontal health with the contralateral canines.

RESULTS

Intergroup comparison results exhibited insignificant differences in all periodontal parameters between the labially and palatally impacted maxillary canines. Intragroup comparison results showed a significant increase in PI, GI, GBI, and PD, and a significant decrease in AGW, KGW, and GT in the impacted teeth compared to the controls, except for PI in the palatally impacted maxillary canines.

CONCLUSION

The decrease in KGW, AGW, and GT was not associated with the pre-eruptive position of the impacted teeth. These side effects seen after orthodontic treatment of impacted teeth should be followed carefully in the long term.

Factors associated with the morphology of the mandibular symphysis and soft tissue chin

Objectives:

This study aimed to (I) assess the morphology of the symphysis and soft tissue chin associated with sex, age and sagittal/vertical skeletal patterns, and (II) identify the individual and combined contributions of these variables to different portions of the symphysis.

Methods:

This cross-sectional study included 195 lateral cephalometric radiographs from untreated adults. Alveolar, basal, and soft tissue of the symphysis were measured by an X/Y cranial base coordinate system, and divided in accordance to four predictor variables: sex, age, and sagittal/vertical skeletal patterns. Parametric tests were conducted for comparison and correlation purposes, while multiple regression analysis was performed to explore combined interactions.

Results:

Alveolar inclination is related to sagittal and vertical patterns, and both explained 71.4% of the variations. Alveolar thickness is weakly predicted and poorly influenced by age. Symphysis height was 10% higher in males, and associated with a vertical skeletal pattern and sex, and both explained 43.6% of variations. Basal symphyseal shows an individual thickness, is larger in males, and vertically short-positioned with age. Soft tissue chin is not necessarily related to the size of the underling skeletal pattern, and enlarges with age, even in adulthood.

Conclusions:

The symphysis and surrounding tissues are influenced by sex, age, and sagittal and vertical patterns, acting differently on the alveolar, basal and soft tissue portions. Sagittal and vertical skeletal patterns are the strongest association on alveolar symphysis inclination, whereas sex and age acts on the vertical symphysis position and soft tissues thickness.

Prevalence of gingival recession and its correlation with gingival phenotype in mandibular incisors region of orthodontically treated female patients: A cross-sectional study

Background:

Gingival recession is associated with dentin hypersensitivity, unesthetic appearance, and carious or noncarious cervical lesions. Orthodontic treatment, gingival thickness (GT), and keratinized tissue width (KTW) play roles in gingival recession etiology. The study is aimed to compare the prevalence of gingival recession in the mandibular incisor region of orthodontically-treated females with untreated controls, and to identify if there is any correlation among the GT, KTW, and gingival recession.

Subjects and Methods:

A total of 150 Saudi females were enrolled in this study. They were categorized into the treatment group (n = 75) and control group (n = 75). Background characteristics and clinical periodontal parameters including the plaque index, gingival index, GT, KTW, gingival recession length (GRL), and gingival recession width (GRW) were recorded and compared between groups, and any associations were identified.

Results:

Among the orthodontically-treated females, 31 (41.33%) had at least one mandibular incisor with gingival recession, in contrast to 18 (24%) of the controls. Pearson's correlation analysis indicated a significant positive correlation between the GT and KTW and between the GRL and GRW (P < 0.001). In addition, a significant negative correlation was observed between the KTW and GRL and between the KTW and GRW (P < 0.001). However, no significant correlation was found between the GT and GRL or between the GT and GRW.

Conclusions:

Our findings indicated that orthodontic treatment is a predisposing factor for the development or progression of gingival recession, particularly in females with a narrow KTW.

Factors associated with alveolar bone depth mesial to the mandibular third molars after orthodontic protraction

INTRODUCTION

The objective of this research was to study the factors associated with the alveolar bone depth mesial to the mandibular third molars (M8) after the mandibular second (M7) and third molars were protracted into the space of the mandibular first molars (M6), which were newly extracted for orthodontic treatment or extracted more than 1 year before treatment.

METHODS

This retrospective study included 57 adult patients (mean age 23.40 ± 4.40 years) in whom M6 were newly extracted for orthodontic treatment or extracted more than 1 year before treatment. The alveolar bone depth mesial to M8 was measured on posttreatment panoramic radiographs. The vertical, horizontal, and angular changes of M8 were measured on both pre- and posttreatment panoramic radiographs. Linear correlation and regression analyses were conducted to explore the factors associated with the alveolar bone depth mesial to M8.

RESULTS

The alveolar bone conditions of M6 (R= -0.391, P <0.001) and the vertical movement directions of M8 (R= -0.433, P <0.001) were significant factors associated with the alveolar bone depth mesial to M8 after orthodontic protraction.

CONCLUSIONS

Without considering the pretreatment periodontal status of M8, patients with M6 extracted exceeding 1 year before treatment and with M8 extruded after orthodontic protraction may exhibit deeper alveolar bone depth mesial to M8.

Change in alveolar bone level of mandibular second and third molars after second molar protraction into missing first molar or second premolar space

Objective

To investigate the factors associated with the change in alveolar bone level of mandibular second and third molars after second molar protraction into the space of the missing first molar (L6) or second premolar (LE).

Methods

Fifty-one patients in whom space of the missing L6 or LE was treated with second molar protraction (13 males, 38 females, mean age 19.6 ± 4.7 years) from 2003 to 2015 were included. The alveolar bone level and position and angulation of the mandibular second and third molars were measured in panoramic radiographs at pre-treatment (T1), and after the alignment of the third molars following second molar protraction (T2). Factors associated with alveolar bone loss on the distal aspect of the mandibular second molars were assessed using linear regression analysis.

Results

Age at T1 (P < 0.001) and third molar angulation at T1 (P = 0.002) were significant factors for the prediction of alveolar bone level distal to the second molars.

Limitation

This study used two-dimensional panoramic radiographs, and we could observe only the interproximal bone level.

Conclusions

After second molar protraction into the missing first molar or second premolar space, mandibular second molars may exhibit alveolar bone resorption in the distal root in older patients and in those with mesially tilted third molars before treatment.

Relationship between periodontal status of mandibular incisors and selected cephalometric parameters : Preliminary results

Purpose

The aim of this cross-sectional study was to evaluate the correlation between the periodontal tissue of mandibular incisors and several dentoalveolar and skeletal cephalometric parameters.

Materials and methods

The sample consisted of 35 patients (mean age 26.42 ± 8.02 years). Eligibility criteria included good overall health status with no history of dental trauma, congenital defects, active periodontal diseases, restorative and prosthetic treatment in the area of the mandibular incisors. Gingival recession width and height (GRW, GRH), gingival thickness (GT), width of keratinized gingiva (WKT) and clinical attachment loss (CAL) were evaluated at 140 lower incisors. Incisors inclination (1-:ML), skeletal class (ANB, WITS), intermaxillary angle (NL:ML) and mandibular symphysis dimensions (symph. length and width) were assessed in cephalograms. Spearman’s correlation coefficient was used for statistical analysis at the P < 0.05 level.

Results

A statistically significant positive moderate correlation was found for GT and WITS and also symph. length. WKT correlated positively with ANB, WITS and symph. length, with moderate strength of the correlation. GRW, GRH and CAL did not correlate with any cephalometric parameters.

Conclusion

The results of this study indicated evidence for an association between WKT and GT and some cephalometric variables—ANB, WITS, and symphysis length.

Dentoalveolar Evaluation of Lower Incisors by CBCT after Treatment with Herbst Appliance

Abstract This study aimed to evaluate the effects of the Herbst appliance on the proclination and protrusion of the lower incisors, and to verify if the device causes alveolar bone loss in the anterior region of the mandible. This is a retrospective study. The sample consisted of 35 individuals. The treatment group consisted of 22 individuals (8 girls and 14 boys; initial mean age of 8.2 years) who used the Cantilever Herbst appliance for a period of 12 months. The control group consisted of 13 individuals (3 girls and 10 boys; initial mean age of 8.9 years) who received no treatment and were followed up for a period of approximately 18 months. Cone-beam computed tomography scans were performed at the beginning and at the end of the observational period. The medullary bone thickness (MT), buccal cortical bone thickness (BCT), lingual cortical bone thickness (LCT), and lower incisors proclination and protrusion were evaluated. Data were submitted to statistical analysis (ANCOVA and Student’s t-test) with a significance level of 5%. There was no significant difference in MT, BCT, LCT and incisor proclination between groups. Incisor proclination increased in the treated group with no statistical significance. The treatment group showed a significant increase in the protrusion of the incisors (p = 0.02). The Herbst appliance promoted a small proclination and protrusion of the lower incisors, without relevant clinical implications. The Herbst appliance did not cause bone loss in the anterior region of the mandible during Class II treatment.