This study investigated the prevalence of and risk factors for alveolar fenestration and dehiscence in the anterior teeth of Chinese patients with skeletal Class III malocclusion.
This study included clinical and radiographic examinations and intraoperative observations of 460 anterior teeth from 54 patients who underwent corticotomy and periodontal regenerative surgery before orthodontic treatment. Fenestration and dehiscence were detected and recorded during open-flap surgery. Univariate and multivariate analyses were performed to assess relationships between fenestration and dehiscence and age, sex, history of previous orthodontic treatment, mandibular plane angle, dentition, tooth position, sagittal root position, periodontal biotype, gingival recession, width of keratinized gingiva, and width of the basal bone.
The prevalence of buccal alveolar bone defects was 16.1% (fenestration) and 20.7% (dehiscence) at the tooth level. Multivariate logistic regressions showed that fenestration was significantly associated with tooth position (canine vs central incisor, odds ratio [OR] = 3.324; P = 0.006; lateral incisor vs central incisor, OR = 5.588; P <0.001), and sagittal root position (buccally positioned vs centrally positioned, OR = 5.865; P = 0.025). Dehiscence was significantly associated with dentition (mandible vs maxilla, OR = 11.685; P <0.001), tooth position (canine vs central incisor, OR = 3.863; P = 0.007), age (OR = 1.227; P = 0.010), sex (male vs female, OR = 5.530; P = 0.026), and history of orthodontic treatment (yes vs no, OR = 4.773; P = 0.028).
Buccally positioned teeth in the osseous housing, lateral incisors, and canines were more likely to exhibit alveolar fenestration. Mandibular teeth and canines, patients who were older, were male, and had a history of orthodontic treatment, were more likely to exhibit alveolar dehiscence.
We studied alveolar defects in Chinese patients with skeletal Class III malocclusion.
Fenestration and dehiscence were identified during open-flap surgery.
Fenestration was associated with buccally positioned teeth, lateral incisors, canines.
Dehiscence was associated with mandibular teeth, especially canines.
Dehiscence was associated with older males with a history of orthodontic treatment.
Two commonly encountered alveolar defects are fenestration, an isolated area in which the root is denuded of bone, and dehiscence, an instance in which the denuded area extends through the marginal bone. These defects are risk factors for gingival recession and root resorption and may influence the periodontal health and esthetic of affected patients.
The high prevalence of fenestration and dehiscence in patients with skeletal Class III malocclusion poses great challenges to their tooth movements. A retrospective study of the combined prevalence of fenestration and dehiscence based on different Angle’s classification of malocclusion showed that 45% of patients with Class III malocclusion exhibited alveolar defects in the mandible, whereas 29% of those patients exhibited alveolar defects in the maxilla. In an Asian population, the combined prevalence was even higher, with 58.52% and 41.48% exhibited defects in the mandibular and maxillary anterior teeth, respectively.
In addition, dental compensations are similar among patients with skeletal Class III malocclusion, typically manifested as proclined maxillary incisors and retroclined mandibular incisors. Orthodontic decompensation is often needed before orthognathic surgery to correct the interference of anterior teeth; this decompensation involves retroclining the maxillary incisors and proclining the mandibular incisors. The presence of fenestration or dehiscence may also increase periodontal risk during the tooth movement. Therefore, thorough investigations of alveolar morphology and the identification of risk factors for alveolar defects are essential before orthodontic treatment is initiated.
Previous studies have shown that several factors are associated with fenestration or dehiscence, including age, sex, and history of orthodontic treatment. , , However, most of these risk factors were identified in univariate analyses, and their effects have not been investigated in multivariate analyses. In addition, limited information is available regarding Asian populations, in which there is a high prevalence of alveolar bone defects. , Therefore, this cross-sectional study aimed to use multivariate analyses to evaluate the prevalence of fenestration and dehiscence and their risk factors in Chinese patients with skeletal Class III malocclusion.
Material and methods
The study protocol was approved by the Research Ethics Committee of Peking University Health Science Center (approval no. PKUSSIRB-201735074). All protocols were performed in accordance with approved guidelines and regulations, and informed consent was obtained from all participants. Patients who underwent corticotomy and periodontal regenerative surgery before orthodontic treatment in the clinic of the Periodontology Department, Peking University School and Hospital of Stomatology, from August 2012 to August 2018 were enrolled in the present study ( Fig 1 ).
Inclusion criteria were as follows: age ≥18 years; the presence of skeletal Class III malocclusion requiring orthodontic and orthognathic treatment, ANB ≤ −5°; healthy periodontal status: full mouth number of sites with deep periodontal pockets (probing depth [PD] ≥5 mm) ≤2, percentage of sites with bleeding on probing ≤20%, and plaque score ≤20%; healthy systemic status.
Exclusion criteria were as follows: the presence of uncontrolled periodontal infection; a history of periodontal surgical treatment in anterior teeth; the presence of systemic disease (eg, diabetes mellitus, nephrosis, hepatopathy, hypertension, or neutropenia), pregnancy, or smoking; use of medication known to affect periodontal status; the presence of cleft lip and palate or maxillofacial abnormalities; and absence of complete clinical and radiographic examination data.
Clinical data were collected by measuring at the buccal-middle site of the anterior teeth using a Williams periodontal probe with notches located at 1-10 mm. The following data were collected: periodontal biotype, categorized as thick or thin based on the transparency of the periodontal probe through the gingival margin while probing the sulcus at the midfacial aspect of the tooth, in accordance with a previously published method ( Figs 2 , A and B ) ; plaque index (0-3) ; PD (mm), which consisted of the distance between the gingival margin and the base of the sulcus or pocket at the midfacial aspect of the tooth; gingival recession (mm), which consisted of the distance between the cementoenamel junction and the gingival margin at the midfacial aspect of the tooth; bleeding index (0-5) ; width of keratinized gingiva (mm), which consisted of the distance between the mucogingival junction and the gingival margin at the midfacial aspect of the tooth ( Fig 2 , C ).
Radiographic data collected in this study were as follows: mandibular plane angle, measured on lateral cephalometric radiograph and classified as low (Mp-SN ≤28°), average (28° < Mp-SN < 38°), or high (Mp-SN ≥38°) ; sagittal root position (SRP) in relation to its osseous housing, classified as Class I (root positioned against the labial cortical plate), Class II (root centered in the middle of the osseous housing without engaging either the labial or the palatal cortical plates at the apical third of the root), Class III (root positioned against the palatal cortical plate), or Class IV (at least two thirds of the root engages both the labial and palatal cortical plates) ( Figs 2 , D – G ) ; width of the basal bone (mm), measured with cone-beam computed tomography (CBCT) (NewTom VG; Aperio Services, Verona, Italy) with an axial thickness of 0.3 mm (sagittal slices were evaluated where the tooth was widest labiolingually in the axial view, and the thickness of alveolar bone perpendicular to the long axis of the tooth at the apex level was recorded as the width of the basal bone) ( Fig 2 , H ).
Detection of fenestration or dehiscence during open-flap surgery was performed as follows. Fenestration was identified as a localized defect in the alveolar bone that exposed the root surface but did not involve the alveolar margin ( Fig 2 , I ). Dehiscence was defined as a defect measuring at least 4 mm apical to the crest of the interproximal bone ( Fig 2 , J ).
All measurements were performed by a single experienced clinical professor of periodontology before periodontal surgery. Calibrations were performed; kappa statistics or intraclass correlation coefficients for intraexaminer agreement regarding measurements of the PD, gingival recession, width of keratinized gingiva, and width of the basal bone ranged from 0.88 to 0.91.
Quantitative data were recorded as means and standard deviations. Continuous data were compared using the Student t test or analysis of variance, whereas categorical data were compared with the chi-square test. Multivariate analyses based on 3-level logistic regression (ie, patient at level 1, dentition at level 2, and tooth at level 3) was used to evaluate the hierarchical and clustered structures of the resulting periodontal data. Fenestration and dehiscence at the tooth (yes vs no) were the dependent variables in logistic regression analyses. Initially, a null model with no independent variables included was constructed to investigate the variance in the dependent variables at all levels. Subsequently, independent variables were included in the multilevel regression model to test their associations with fenestration and dehiscence. The significance level for all tests was set at P <0.05. Data were evaluated with SPSS Statistics software (version 19.0; IBM, Armonk, NY).
The flow chart of patient selection and screening is shown in Figure 1 . In total, 460 maxillary and mandibular anterior teeth from 40 maxillae and 37 mandibles of 54 patients were included in the analyses. The demographic characteristics of included patients and clinical and radiographic parameters of included teeth are reported in Table I . The mean age of patients was 23.50 years, and 74.1% of the patients were females. The percentages of patients with high, average, and low mandibular plane angle were 77.8%, 11.1%, and 11.1%, respectively. In addition, 25.9% of the patients had undergone orthodontic treatment before participating in this study.
|Mandibular plane angle|
|Previous orthodontic history|
|Dehiscence or fenestration|
|Sagittal root position|
|Gingival recession, mm||0.06||0.28||0||3|
|Probing depth, mm||1.53||0.55||1||3|
|Width of keratinized gingiva, mm||4.06||1.54||0||8|
|Width of the basal bone, mm||7.64||2.40||2.22||16.73|