The effect of changes in lower incisor inclination on gingival recession

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.

Factors affecting the maxillary and mandibular incisors' buccolingual inclinations and buccal and lingual cortical plate heights

INTRODUCTION

Orthodontics is closely related to periodontics. The buccolingual inclination (BLI) of the incisors and deficiencies in their buccal (BHd) and lingual (LHd) cortical plate heights may affect orthodontic outcomes. Identifying risk factors that can compromise buccal or lingual bone heights may have clinical value. The literature on BLI/BHd/LHd is not only scarce but also limited to one jaw. We aimed to examine, for the first time, factors affecting BLI/BHd/LHd not evaluated before as well as other factors with scarce literature about them.

METHODS

In this two-phase epidemiological and analytical study, inclinations and cortical heights of 248 incisors (bilateral centrals and laterals) were evaluated blindly on 62 randomly selected high-resolution pretreatment cone-beam computed tomography volumes (30 maxillae [13 men, 17 women], 32 mandibles [13 men, 19 women]). The sample was balanced in terms of sexes, jaws, and ages. The BLI/BHd/LHd of bilateral incisors were measured (intraobserver agreement > 95%). The effects of jaws, sexes, age, sides, and incisor types on each of the anatomical variables (BLI/BHd/LHd) were analyzed using a Mixed-Model Multiple Linear Regression analysis. Correlations among continuous variables were assessed using a Pearson coefficient (α = 0.05).

RESULTS

For the maxillary centrals, BLI, BHd, and LHd were 106.79 ± 5.06, 1.94 ± 0.95, and 1.50 ± 0.76, respectively. These parameters were '110.56 ± 5.97, 1.81 ± 0.83, 1.23 ± 0.69' for the maxillary laterals; '97.64 ± 8.26, 2.98 ± 1.48, 3.46 ± 1.45' for the mandibular centrals; and '95.98 ± 6.80, 3.29 ± 1.72, and 2.73 ± 1.15' for the mandibular laterals. BLI was greater in the maxilla compared to the mandible and in the lateral incisors compared to centrals (P < 0.05). BHd was greater (more deficient) in the mandible (P = 0.000). Age, sex, or side were not associated with BLI (P > 0.05). Age, sex, side, or incisor types were not associated with BHd (P > 0.05). LHd was greater in the mandible, older individuals, and centrals (P < 0.05). There were some significant but weak correlations between BLI with BHd and especially LHd (P < 0.05).

CONCLUSION

In the maxilla, but not in the mandible, incisors' BLI may determine LHd. Maxillary incisors may have greater BLIs as well as greater buccal and lingual alveolar bone heights compared to mandibular incisors. BLI might be greater in the laterals compared to the centrals in both jaws combined.

Assessment of gingival biotype in different facial patterns: A cross-sectional study

Objective

The aim of the present study is to evaluate the relationship of gingival biotype in different malocclusions.

Methods

A total of 157 periodontally healthy subjects (88 males and 69 females) were enrolled in this cross-sectional study. The study participants were divided into three groups of skeletal class I, class II, and class III. The probe transparency method was used to determine the quality and gingival tissue into thick and thin biotype.

Results

There was significant difference in gingival biotype among different skeletal malocclusion with high prevalence of thin gingival biotype in class I subjects and more prevalence of thick biotype in class II and class III individuals (P-value: 0.022). Pairwise comparison of gingival biotype in class I versus class II showed significant difference (P-value: 0.032); however in class I versus class III and class II versus class III, the test result was nonsignificant. The overall frequency of thin gingival biotype was significantly less in female subjects with respect to males (P-value: 0.025).

Conclusion

A significant relationship is present between skeletal malocclusion and quality of gingival biotype. The prevalence of thick gingival biotype is found more in females as compared to male individuals. The thin gingival biotype is more commonly seen in skeletal class I than class II and class III.

Perceptions of NZ orthodontists and periodontists on the management of gingival recession in orthodontic patients

BACKGROUND

This study aimed to investigate the perceptions and opinions of orthodontists and periodontists on the management of gingival recession in orthodontic patients.

METHODS

An online survey was sent to 29 periodontists and 80 orthodontists registered and currently practising in New Zealand. All participants answered questions about the timing and clinical indications of mucogingival surgeries in orthodontic patients diagnosed with mucogingival deformities.

RESULTS

Most periodontists and orthodontists believed that gingival grafts should ideally be performed after orthodontic treatment. In clinical practice, 40% of periodontists indicated that they would receive referrals after completion of orthodontic treatment. However, 29.6% of orthodontists indicated that they would refer to a periodontist before orthodontic treatment in clinical practice. The most crucial factor that affected periodontists' decision-making was 'evidence-based guidelines' (35.0%), followed by 'clinical experience' (30.0%) and 'patient concerns' (15.0%). All four factors of 'gingival phenotype', 'presence of gingival recession', 'amount of keratinised tissue' and 'planning specific tooth movements' were equally considered by orthodontists regarding their decision-making.

CONCLUSIONS

The majority of the surveyed New Zealand periodontists and orthodontists expressed a belief that the ideal timing for the management of gingival recessions would be after the completion of orthodontic treatment.

The effect of orthodontic treatment on the periodontium and soft tissue esthetics in adult patients

OBJECTIVE

Most patients seek orthodontic treatment to achieve an esthetic outcome. Orthodontic treatment has possible negative sequelae. The aim of this study is to assess these possible effects on the periodontium and tissue esthetics.

METHODS

One hundred fifty-six patients who have completed orthodontic treatment at Jordan University of Science and Technology clinics were recruited. They were divided into extraction and nonextraction subgroups. Another 155 patients never undergoing orthodontic treatment were assessed. The height of papilla, width of keratinized gingiva, gingival recession, degree of tooth display, smile line, crestal bone level, and proximal caries were assessed. Chi- square test was used for categorical/discrete variables while independent t-test was used for continuous variables. The level of significance was set at (p ≤ 0.05).

RESULTS

The mean age was 22 years with no significant difference between the groups. There was a significant difference between "ortho" and "nonortho" groups in tooth display and keratinized gingiva (p = 0.006 and <0.001, respectively). The overall crestal bone level, smile line, recession, and papilla fill did not show any significant differences (p = 0.200, 0.067, 0.120, and 0.066, respectively). The crestal bone level in the upper and lower anterior segments was significantly lower in the "ortho" treated group compared to the "nonortho" treated group (p = 0.002 and 0.005, respectively). A significant difference between "extraction" and "nonextraction" groups was in the width of keratinized gingiva (p = 0.003) and the number of teeth displayed (p < 0.001). Despite reaching statistical significance these differences are not necessarily of clinical significance.

CONCLUSION

Orthodontic treatment clearly affects the periodontal tissues; however, the detrimental effects appear to be minimal. Patients with history of orthodontic treatment might have lower crestal bone levels at certain sites and this should not be confused with periodontal disease.

Personalized Orthodontics: From the Sagittal Position of Lower Incisors to the Facial Profile Esthetics

Background: One of the goals of orthodontic treatment is to obtain maximum facial harmony. The sagittal position of the lower incisors plays a significant role in the planning of orthodontic treatment. The aim of the study was to evaluate the relationship between the sagittal position of lower incisors and facial profile esthetics with reference to the skeletal vertical dimension. Methods: There were 200 patients included in the study. Patients were allocated into three groups, depending on the vertical growth pattern: normal-angle, low-angle, and high-angle cases. Tweed–Merrifield cephalometric analysis was used to assess the sagittal and vertical position of the mandible, as well as to assess the sagittal position of the lower incisors. Results: Z-angle and Frankfort mandibular incisor plane angle (FMIA) decreased significantly (p < 0.001) with the increase of the skeletal vertical dimension. Incisor mandibular plane angle (IMPA) was significantly higher (p < 0.001) in low-angle patients compared to the high-angle ones. Z-angle appeared to be the most accurate parameter (area under curve, AUC = 0.957) describing patients with a convex profile. The cutoff value of Z-angle 68.0° was characterized by the sensitivity of 94.1% and the specificity of 84.3%. Conclusions: The sagittal position of the lower incisors significantly affects the facial profile convexity. The Z-angle is the parameter which most accurately describes the patients with a convex profile.

Post-Orthodontic Lower Incisors Recessions: Combined Periodontic and Orthodontic Approach

The bonded lingual retainer (BLR) is considered a favorable choice for retaining lower incisors' alignment post-orthodontic treatment; however, it may cause some unwanted effects such as inadvertent tooth movement and torque changes. These often result in gingival recession (Miller class III-type) with exposure of the root surface, which compromises the esthetics and hinders the comfort of the patient. Fifteen post-orthodontic patients presenting Miller class III-type recessions with BLR were examined. Two protocols were used: the first included the removal of the BLR prior to surgery and the second included only a surgical approach. All patients underwent the same surgery of a modified tunnel double papilla procedure for root coverage. The gingival recession was measured using a dental probe before, and three to six months post-surgery. The average improvement in recession depth was significantly greater (p = 0.008) for the protocol that included removal of the BLR (4.0 ± 0.83 mm) with an improvement of 87.2% as compared to the second protocol that showed an improvement of 43.8% (1.88 ± 1.29 mm). Removing the BLR prior to surgery is beneficial for predictable root coverage in post-orthodontic Miller class III recessions.

Selective piezocision-assisted orthodontic treatment combined with minimally invasive alveolar bone regeneration: A proof-of-concept

BACKGROUND

Piezocision is a localised piezoelectric alveolar decortication involving minimally invasive corticotomies to accelerate orthodontic treatments. The objective of this proof-of-concept was to describe an innovative protocol combining selective piezocision with minimally invasive bone regeneration to reduce the risk of buccal tissue dehiscences often observed in orthodontic treatments. This proof-of-concept initial report aimed at investigating whether this new surgical concept is relevant.

MATERIALS AND METHODS

A patient presenting an asymmetrical dental class II, overcrowdings, midline deviations and buccal bone dehiscences in the lower incisor region was treated with this new treatment approach.

RESULTS

From an orthodontic point of view, the dental class II, the overcrowdings and the midlines were completely corrected. From a periodontal perspective, no gingival recession was observed; however, scars related to the piezocision were slightly visible at the mandible. The post-imaging demonstrated the absence of bone dehiscences. Up to 3 years after the completion of the treatment, no relapse was observed.

CONCLUSION

This novel approach suggested several advantages and may be further investigated at a larger scale in order to validate the benefits and to define the scope of intervention.

Effects of crown movement on periodontal biotype: a digital analysis

Orthodontic treatment has important correlations with periodontal changes. Various mechanical and biological factors are involved in determining such changes, but anatomical and morphological variables, generally addressed as periodontal biotype, play a key role. In measurement of such modifications, digital and non-contact reverse engineering technologies may be of tremendous advantage. The aim of this study is to retrospectively evaluate, in a series of digitized dental casts, some of the parameters addressing periodontal biotype and correlate them to extent and direction of tooth movement. Pre- (T0) and post-treatment (T1) dental casts of 22 patients were scanned by 3Shape TRIOS 3® scanner. A number of variables (crown ratio, gingival margin position, gingival contour, papillae position, gingival scallop) were investigated and their variations calculated after digital measurements on single casts at T0 and T1, or after direct measurement (T1 vs T0) on the superimposition and alignment of digital models. Univariate and multivariate statistics were then performed. No significant correlation was detected between the sagittal or vertical movement of dental crown and displacement of the gingival margin. On the other hand, vestibular gingival contour resulted significantly altered by vestibular and extrusion movements. Further studies are needed to ascertain the differential effect of bone and soft tissue on such modifications. The relationship between orthodontic treatment and the periodontium overcomes the consideration of gingival recession and includes all the concepts of periodontal biotype with its characteristics. Digital technologies and non-contact reverse engineering techniques now available have the potential to allow a more precise definition of such a relationship.

Gingival recession: its causes and types, and the importance of orthodontic treatment

Gingival recession has direct causes and predisposing factors. Orthodontic treatment is able to prevent recession and even contribute to its treatment, with or without periodontal approach, depending on the type and severity of gingival tissue damage. There is no evidence on the fact that orthodontic treatment alone might induce gingival recession, although it might lead the affected teeth (usually mandibular incisors or maxillary canines) to be involved in situations that act as predisposing factors, allowing direct causes to act and, therefore, trigger recession, especially when the buccal bone plate is very thin or presents with dehiscence. Several aspects regarding the relationship between orthodontic treatment and gingival recession have been addressed, and so has the importance of the periosteum to the mechanism of gingival recession formation. Clinical as well as experimental trials on the subject would help to clarify this matter, of which understanding is not very deep in the related literature.

Mandibular Incisor Position Changes do not Explain Increase in Keratinized Gingiva Height after Periodontally Accelerated Osteogenic Orthodontics

Purpose

This study aimed to reexamine the relationship between mandibular incisor inclination, prominence and vertical changes in position, and keratinized gingival tissue (KT) height changes labial to the mandibular incisors after orthodontic treatment with and without augmented corticotomy (Cort).

Materials and Methods

Two orthodontically treated groups of 35 individuals each, with (Cort) and without (conventional [Conv]) alveolar decortication and augmentation bone grafting (periodontally accelerated osteogenic orthodontics [PAOO]), were matched for sample size, gender, mandibular premolar extractions, pretreatment age, posttreatment observation period, and pretreatment KT height in this case–controlled retrospective study. Pre- and post-treatment lateral cephalometric radiographs were evaluated for mandibular incisor vertical, inclination, and prominence changes.

Results

As reported previously (Wilcko 2015), KT height had significantly increased by 0.78 mm (P = 0.001) in the Cort group and decreased by 0.38 mm (P = 0.002) in Conv on an average of 1.5 years after completion of active orthodontic therapy. In this study, Cort mandibular incisors proclined and protruded significantly during therapy while Conv incisors did not. Changes in mandibular incisor inclination and prominence explained neither the decrease in keratinized gingiva height in Conv nor the KT height gain in Cort.

Conclusions

In spite of mandibular incisor proclination and protrusion, orthodontic therapy combined with alveolar decortication and augmentation bone grafting resulted in a clinically significant increase in keratinized gingiva height 1.5 years’ posttreatment.

An evaluation of the gingival biotype and the width of keratinized gingiva in the mandibular anterior region of individuals with different dental malocclusion groups and levels of crowding

Objective

To evaluate the relationship of gingival thickness (GT) and the width of keratinized gingiva (WKG) with different malocclusion groups and the level of crowding.

Methods

A total of 187 periodontally healthy subjects (121 females and 66 males) who presented at the Faculty of Dentistry in Yüzüncü Yıl University for orthodontic treatment were enrolled in the study. The individuals involved in the study were divided into three groups; Angle Class I malocclusion, Angle Class II malocclusion, and Angle Class III malocclusion. Each group was classified as mild, moderate, or severe according to the level of crowding. WKG was determined as the distance between the mucogingival junction and the free gingival margin. GT was determined by the transgingival probing technique. Factorial variance analysis and the Duncan multiple comparison test were employed to identify the extent to which a difference was apparent between the groups according to these parameters.

Results

It was determined that teeth in the mandibular anterior region display the thin gingival biotype. WKG and GT were observed as being higher at the mandibular incisor teeth in the severe crowding group and at the mandibular canine teeth in the mild crowding group. The GT of the mandibular right central and lateral incisors was found to be thinner in the Angle Class III group.

Conclusions

Within the limits of this study, the results demonstrate that, there is no significant relationship of WKG and the mean GT in the mandibular anterior region according to the Angle classification.