Analysis of the Volumetric Asymmetry of the Mandibular Condyles Using CBCT

ObjectivesThe aim of this study was to analyse volumetric asymmetries between the right and left condyles in relation to age, gender, and dental status.Materials and methodsA retrospective analysis of 150 cone beam computed tomography (CBCT) scans was conducted. A single investigator performed the volumetric analysis of the CBCT scans using Vesalius 3D software. The volumetric data were analysed in relation to the gender, age, and dental status.ResultsThe mean right condylar volume was significantly higher (P < .01) than the left condylar volume. Right and left condylar volumes were significantly higher (P < .01) in male study participants when compared to female study participants. There was no significant difference (P = .47) in the volumetric asymmetry between the male and female study participants. The volumetric asymmetry was significantly higher (P < .01) in the older age groups when compared to the younger age groups. The volumetric asymmetry was significantly higher (P < .01) in the partially and completely edentulous patients when compared to the dentate study participants. The condylar volume on the side having a partially edentulous area was significantly lower than the condylar volume of the contralateral dentate side (P < .001).ConclusionsThe volumetric asymmetry between the right and left condyle significantly increases with age and edentulousness. The result of the study encourages the clinicians to perform volumetric evaluation of the condyles in cases of radiographically evident condylar asymmetries to obtain a more accurate diagnosis.     

Correlation of gonial angle size with cortical thickness, height of the mandibular residual body, and duration of edentulism

STATEMENT OF PROBLEM: Previous reports on widening of the gonial angle in edentulous patients are conflicting. Aside from age and loss of teeth, other factors may influence change in gonial angle. PURPOSE: This study evaluated gonial angles from panoramic radiographs of young and older dentate subjects and elderly edentulous subjects and investigated the relationship of gonial angle size to gender, age group, cortical thickness at the gonial angle, height of the mandibular residual body, and edentulous period in elderly edentulous subjects. MATERIAL AND METHODS: A total of 356 panoramic radiographs of 3 groups of subjects were evaluated: the young dentate group, 131 subjects (mean age 27 years); the older dentate group, 97 subjects older than age 52 (mean age 64 years); and the elderly edentulous group, 128 subjects aged 76, 81, or 86 (mean age 80 years). The gonial angle, cortical thickness at gonial angle, and height of mandibular residual body were measured from panoramic radiographs made with the same radiographic equipment and selected according to criteria. A structured questionnaire was used to determine the history of edentulism. Paired and unpaired 2-tailed t tests served to test the difference in gonial angle measurements, and a linear regression was performed to study correlations (alpha=.05). RESULTS: Difference in size of the gonial angle was found between dentate men and women (P<.05 in the young and P<.001 in the older dentate group), but not between elderly edentulous men and women. The elderly edentulous subjects had significantly larger gonial angles (128.4 degrees +/- 6.6) than did the young (122.4 degrees +/- 6.6, P<.001) and older dentate subjects (122.8 degrees +/- 6.6, P<.001). The angle size was negatively related to cortical thickness at the gonial angle only among 76-year-old edentulous women (P<.01), and was associated with average height of the mandibular residual body in the edentulous men and women (P<.01). No association existed between angle size and duration of edentulism. No differences were significant in any test of intraexaminer error. CONCLUSION: In this study, elderly edentulous subjects had larger gonial angles than did dentate subjects. The angle size was correlated with low height of the mandibular residual body and with its cortical thickness in edentulous women.     

Bilateral Posterior Dislocation of Mandibular Condyle: A Rare Entity in Maxillofacial Injuries

BackgroundDislocation of the mandibular condylar head refers to ectopic positioning of the intact condylar head out of the glenoid fossa. Most commonly reported anterior dislocation results from anteromedial pull of the lateral pterygoid muscle and laxity of the surrounding tissue with advanced age.PurposeThis case report brings forth a unique case of bilateral posterior condylar dislocation in an edentulous patient who reported after 4 weeks of traumatic injury.MethodThe condition was managed surgically by reduction of the dislocated condyle and placement of mersilene tape on one side and temporalis muscle on the other side as anchorage ligament to stabilize the condyle and prevent any future recurrence.ResultsThe patient was maintained on long-term follow-up for up to one year with no reported recurrence or reduction in mouth opening.ConclusionThis is the first ever case report that highlights bilateral posterior dislocation of intact mandible unlike the previous four reports which have brought forth unilateral dislocation on English literature search. Posterior dislocation of mandibular condyle is encountered in edentulous patients who experience posteriorly directed impact which forces the condylar head behind the postarticular ridge. Unlike anterior dislocation, clinical features include reduced mouth opening and retruded mandible in bilateral dislocation. It has been observed that manual correction by pressing the mandible downwards and forwards yields good results in early cases. Cases that are reported late require surgical exploration for reduction and placement of anchorage ligament to prevent recurrence in unstable condyle.     

Morphological magnetic resonance imaging study of oral submucosal tissue and buccinator muscle dynamics in the posterior dentition: A clinical study

Statement of problemThe relationship between the buccal mucosa-tongue side wall contact points and at what ratio the submucosal tissue (ST) and buccinator muscle (BUC) change during function are unclear.PurposeThe purpose of this clinical study was to clarify the space and dynamics of the ST and BUC in complete denture wearers by using magnetic resonance imaging and to investigate how denture base shape affects space sealing and the relationship between the ST and BUC.Material and methodsEight edentulous participants wearing maxillary and mandibular complete dentures were enrolled. Wax was added to the buccal border of the dentures, and axial and coronal magnetic resonance imaging scans were made during mandibular rest (MR) to observe the relationship of the buccal mucosa and tongue above the retromolar pads. In addition, on axial images, the thicknesses of the ST and BUC were measured at 3 sites: second molar center, second molar distal (SMD), and retromolar pad center (RPC). Coronal images were made during MR, partial mouth opening, and midmouth opening (MMo). At second molar center, SMD, and RPC, the thicknesses of the ST and BUC were measured at the maxillary buccinator attachment region (point A), the mandibular buccinator attachment region (point B), and the median point between A and B (point M).ResultsDuring MR, contact sealing of the buccal mucosa and tongue on the RPC was noted in 81% of participants. After expanding the denture base with wax, contact was lost in 86% of participants. The ST and BUC thicknesses on the RPC decreased significantly with the addition of wax. During MR, the ST became significantly thicker the further posteriorly it was located. The ST was significantly thicker at point M than at point A for all sections, regardless of mouth opening. The ST and BUC thicknesses in SMD and RPC were significantly thicker at point M than at point B during MR and MMo. The differences of the ST and BUC thicknesses depending on the opening amount were observed only at the point M. In the RPC, the thickness of the ST and BUC decreased significantly as the opening amount increased (ST thickness between MR and partial mouth opening, MR, and MMo: P=.007, P=.001, BUC: P=.018, P=.001, respectively)ConclusionsThe thickness of the ST and BUC differed depending on the site. During mouth opening, these changes in thickness at each site are proportional to the differences in ST and BUC thickness.     

Correlation between temporomandibular joint temporal component pneumatization and morphology: analysis by cone beam computed tomography

The aim of this study was to evaluate whether a correlation exists between temporal bone pneumatization and the morphology of the articular eminence and glenoid fossa. A sample of 100 cone beam computed tomography scans was used, for a total of 200 temporomandibular joints (TMJ). Paracoronal and parasagittal images of the TMJ were evaluated by two examiners. For all TMJ, pneumatization was classified in the mid-lateral direction using a score of 0 or 1, and in the anteroposterior direction using a score ranging from 0 to 3. The inclination and height of the articular eminence and the thickness of the roof of the glenoid fossa were obtained. Pneumatization was found in the mid-lateral direction in 83.5% of the cases and in the anteroposterior direction in 88%. The age of the patient and side did not influence the prevalence or degree of pneumatization (P = 0.051–0.953), but female patients showed more pneumatization in the mid-lateral direction than male patients (P = 0.014). The presence of pneumatization did not affect articular eminence and mandibular fossa morphology. It is concluded that the presence and extent of pneumatization of the TMJ temporal component does not affect its morphology. However, professionals should be aware of the high prevalence of pneumatization and take this into account when performing TMJ assessment.     

Ethnic differences in craniofacial and upper spine morphology in children with skeletal Class II malocclusion

Objectives:To analyze differences in upper cervical spine and craniofacial morphology, including posterior cranial fossa and growth prediction signs, between Danish and South Korean pre-orthodontic skeletal Class II children and to analyze associations between upper cervical spine morphology and craniofacial characteristics.Materials and Methods:One hundred forty-six skeletal Class II children—93 Danes (54 boys and 39 girls, mean age 12.2 years) and 53 Koreans (27 boys and 26 girls, mean age 10.8 years)—were included. Upper spine morphology, Atlas dimensions, and craniofacial morphology, including posterior cranial fossa and growth prediction signs, were assessed on lateral cephalograms. Differences and associations were analyzed by multiple linear and logistic regression analyses adjusted for age and gender.Results:Significant differences between the ethnic groups were found in the sagittal and vertical craniofacial dimensions (P < .001), mandibular shape (P < .01), dental relationship (P < .01), posterior cranial fossa (P < .05), and growth prediction signs (P < .001). No significant differences were found in upper spine morphology and Atlas dimensions between the groups. Upper spine morphology/dimensions were significantly associated with the cranial base angle (P < .01), sagittal craniofacial dimensions (P < .001), posterior cranial fossa (P < .001), and growth prediction signs (P < .05).Conclusions:Upper spine morphology/dimensions may be valuable as predictive factors in treatment planning for growing Class II children.     

Associations between the articular eminence inclination and condylar bone changes, condylar movements, and condyle and fossa shapes

Objectives

The purpose of the present study was to determine the inclination and height of the articular eminence with respect to the condylar bone changes, condyle shape, fossa shape and condylar movements in patients with and without temporomandibular joint (TMJ) dysfunction using cone-beam computed tomography (CBCT).

Methods

The associations between the eminence inclination and the condylar bone changes, condylar movements, condylar shape and fossa shape were evaluated in patients with TMJ disorders and control patients without TMJ disorders. The measurements of the articular eminence inclination were established on central sagittal slices of the TMJ. The central coronal slices were used to determine the condyle and fossa shapes. The types of movements of the condyles were determined on open-mouth images, and mandibular hypermobility or hypomobility was noted for each joint.

Results

There were no significant differences in the eminence inclination and height with respect to the condylar bone changes and condylar movements in the TMJ disorder group. However, there was a significant association between the eminence inclination and the fossa shape in the TMJ disorder group and significant associations between the eminence inclination and both the condyle and fossa shapes in the control group. The articular eminence inclination was steeper in the control group than in the TMJ disorder group.

Conclusions

The eminence inclination was steeper in the control patients than in the patients with TMJ disorders, and was not correlated with the condylar bone changes or condylar movements.     

Evaluating the effects of functional orthodontic treatment on mandibular osseous structure using fractal dimension analysis of dental panoramic radiographs

ObjectiveTo evaluate the effects of functional appliance treatment on mandibular trabecular structure using fractal dimension (FD) analysis of dental panoramic radiographs.Materials and MethodsThis study was conducted using digital panoramic radiographs of 45 patients with Class II malocclusion treated with functional appliances (treatment group, mean age: 11.39 ± 0.97 years; 23 girls, 22 boys) acquired before (T0) and after (T1) treatment and the panoramic radiographs of 45 control subjects who had undergone no orthodontic treatment (control group, mean age: 11.31 ± 0.87 years; 23 girls, 22 boys). FD values in the condylar process, mandibular corpus, and mandibular angle were analyzed from the panoramic radiographs of both groups.ResultsAnalysis of changes in FD between T0 and T1 revealed significant increases in the FD values of the right and left condylar processes and right mandibular corpus in the treatment group (P < .001) and in the right condylar process in the control group (P < .05). Between-group comparisons demonstrated that the treatment group showed greater changes in the condylar process (right, P < .001; left, P < .05) and right mandibular corpus (P < .05) compared to controls. Correlation analysis between the cephalometric and FD changes in the treatment group showed the right condylar process changes were negatively correlated with GoGn/SN angle (P < .05) and positively correlated with Co-Go (P < .05), although these correlations were weak.ConclusionsFD analysis demonstrated significant changes in trabeculation of the condyle and mandibular corpus in the treatment group compared to the control group. Functional appliance treatment may lead to skeletal correction by altering skeletal form and trabeculation of the mandibular bone.     

Cone beam computed tomographic assessment of mandibular condyle in Kennedy class I patients

Objectives

The aim of this study was to assess the dimensional and volumetric changes in the mandibular condyle in Kennedy class I patients versus completely dentate patients by cone beam computed tomography (CBCT) to estimate the effect of loss of posterior teeth on the mandibular condyle.

Patients and methods

This study was performed on one hundred patients requesting CBCT scans: fifty Kennedy class I patients and fifty fully dentate controls. Condyle dimensions mesio-distal, cranio-caudal and antero-posterior as well as condyle volume were measured in both the groups.

Results

Kennedy class I patients showed statistically significant higher mean condyle width but lower mean condyle height than the control group. No statistically significant difference was found between the study group and the control group regarding condyle AP dimension. There was no statistically significant difference between condyle volumes in the two groups.

Conclusion

Loss of posterior teeth is accompanied by significant decrease in condyle height and increase in condyle width with no change in the total condyle volume or antero-posterior dimensions.

     

Intaglio surface trueness of milled and 3D-printed digital maxillary and mandibular dentures: A clinical study

Statement of problemWhile the dimensional accuracy of the intaglio surface of a removable complete denture is key to its adaptation, comfort, and clinical performance, information on the ability of milling and 3D-printing workflows to accurately reproduce this surface is lacking.PurposeThe purpose of this clinical study was to compare the trueness of the intaglio surface of milled and 3D-printed removable complete digital dentures.Material and methodsIntraoral scans were obtained from 14 participants for a total of 20 edentulous arches. Ten maxillary and 10 mandibular denture bases were then designed and fabricated with a completely digital workflow, both with milling and 3D-printing. Fabricated dentures were digitized with the same intraoral scanner used to obtain intraoral digital scans of the edentulous arches. Standard tessellation language (STL) files of the printed and milled denture bases were used for 3D analysis and comparisons with the STL file of the corresponding designed denture base. Specifically, a reverse engineering software program was used to trim and extract intaglio surfaces, align them, and measure their global mean 3D distance. In order to evaluate the homogeneity of production accuracy of each manufacturing process, the intaglio surfaces were also divided into several regions of interest and the corresponding 3D distances measured. Within- and between-group differences and maxillary and mandibular dentures differences were assessed with parametric and nonparametric tests (α=.05).ResultsMilling showed a global better trueness of the entire intaglio surface (-0.002 mm) than 3D-printing (0.018 mm), both for the whole data set (P<.001) and for maxillary (P=.032) or mandibular (P=.049) denture base subgroups. Within each fabrication technology, maxillary (P<.11) and mandibular dentures (P=.2) showed no significant difference in trueness. Measured deviations were significantly different from zero for the 3D-printed dentures (P<.001), but not for the milled dentures (P=.487). Additionally, for milled dentures, no significant difference in trueness was found among the 11 regions of interest identified for the maxillary dentures (P=.085) and the 13 regions of interest for the mandibular dentures (P=.211). Conversely, 3D-printing showed significant variations in trueness among the same zones of interest, both in maxillary (P<.001) and mandibular (P=.004) dentures.ConclusionsWithin the limits of the manufacturing methodologies used for complete dentures, milling can provide a slightly better trueness of the intaglio surface than 3D-printing, with less variation across several zones of interest. However, given the magnitude of such differences, they may be reasonably considered to be of limited, if any, clinical significance.     

Changes in the position of the condyle after bilateral sagittal split ramus osteotomy in patients with mandibular retrusion and protrusion: a new condyle: fossa matching concept

The purpose of this study was to compare the condylar positional changes after bilateral sagittal split ramus osteotomy (BSSRO) in patients with mandibular retrusion and those with mandibular prognathism. We also studied the correlation between the degree of matching of the condyle and fossa, and condylar displacement. Thirty patients with mandibular retrusion (n = 11) or mandibular prognathism (n = 19) who underwent BSSRO were included. The condylar position was assessed from spiral computed tomographic (CT) scans taken preoperatively, during the first postoperative week, and at least 6 months postoperatively. All data were measured by MIMICS 17.0 and analyzed by Student’s t test and Pearson’s correlation analysis. The size of the condyles of patients with mandibular retrusion was significantly less than those of patients with mandibular prognathism (491.5 (172.8) compared with 823.2 (212.0) mm³). The size of the glenoid fossa in those with mandibular retrusion (599.6 (110.4) mm³) and those with prognathism (597.6 (151.6) mm³) did not seem to differ. Postoperatively the condyles moved outwards, backwards, and downwards in both groups of patients. Correlation analysis between the condyle:fossa volume ratio and the condylar positional changes showed that a large condyle:fossa volume ratio correlated with the smaller positional changes in the condyle. The condylar position changed immediately after mandibular advancement and setback, and persisted in the long term. Larger condyles tended to have fewer positional changes.     

Helicobacter pylori in dental plaque and gastric mucosa

ObjectivesThe aim of this study was to investigate the presence of Helicobacter pylori in both dental plaque and gastricmucus.Study designDental scaling hand instruments were used to collect supragingival and subgingival dental plaque from 81 dentate participants. Denture plaque was obtained from the fitting surfaces of dentures from 41 edentulous patients. Gastric mucus from gastric mucosa of antrum and body of stomach were collected from all 122 participants (92% white) with a soft gastroscopic brush. These samples were dispersed in modified urea broth and normal saline solution before being inoculated onto selective Skirrow's agar and incubated in a microerophilic atmosphere for culturing H. pylori.ResultsDental plaque from all dentate participants was negative for H. pylori culture. Only one 80-year-old edentulous patient had positive H. pylori culture in both gastric mucus and denture plaque.ConclusionsAlthough dental plaque has a mixed flora that may act as a reservior for gastric reinfection, dental plaque could not be implicated as the major reservoir of H. pylori for gastric reinfection.     

无牙下颌角大小与其皮质骨厚度和剩余牙槽骨高度的关系

目的　分析无牙下颌角角度的变化 ,探讨其角度与性别、年龄、下颌角骨皮质厚度、剩余牙槽骨高度及无牙颌时间的关系。方法　年轻有牙组 131例 ,女性 6 8例 ,男性 6 3例 (平均年龄 2 7岁 ) ,年长有牙组 97例 ,女性 5 9例 ,男性 38例 (平均年龄 6 5岁 ) ,老年无牙颌组 12 8例 (平均年龄 80岁 ,76岁者 5 8例 ,81岁者 39例 ,86岁 31例 )。 3组共拍摄 35 6张曲面断层片。分别测量曲面断层片下颌角角度、无牙下颌角区骨皮质厚度和剩余牙槽骨高度。用调查问卷收集无牙颌患者的病史资料。结果　年轻有牙组和年长有牙组的下颌角大小差异无显著性 ,但两组男性下颌角均小于女性下颌角 (P <0 0 5 ,P <0 0 0 1)。老年无牙颌组下颌角为 12 8 4 °± 6 6 °,大于年长有牙组 ( 12 2 8°± 6 6 °) ,二者间差异有极显著性 (P <0 0 0 1)。 76岁无牙女性组 ,下颌角的大小与下颌角区骨皮质厚度呈负相关 (P <0 0 1) ;无牙颌男性和女性下颌角大小均与剩余牙槽骨平均高度呈负相关 (P <0 0 1)。无牙下颌角角度与无牙颌时间无关。结论　无牙患者较有牙者下颌角增大以及剩余牙槽骨越低下颌角越大的结果说明 ,自然牙列和全口义齿的咀嚼功能可能对下颌角的角度有显著影响。无牙下颌角的大小与其骨皮质厚度的显著关系提示 ,系     

3D vector analysis of mandibular condyle stability in mandibular setback surgery with bicortical bioabsorbable screw fixation

IntroductionBioabsorbable screws became widely used for stable fixation in orthognathic surgery as biomechanical technology advanced. Recently, 3D image analyses begin to be used to evaluate surgical changes. The purpose of this study was to evaluate, using 3D vector analysis, the stability of bicortical bioabsorbable screw fixation in mandibular setback using a sagittal split ramus osteotomy.Spatial change of the mandibular condyle was determined by 3D coordinates containing directional information.Materials and methodsBicortical screw fixation was performed using either a bioabsorbable screw (25 patients) or a titanium screw (5 patients) in orthognathic surgery. Pre- and post-operative CT images (6 months after surgery) were superimposed digitally. A 3D coordinate (X, Y, Z) and vectors were employed to quantify spatial changes of the condyle and analysed statistically.ResultsMeasuring on 3D image showed stable error about 0.16 mm. There were no significant differences in the total spatial changes of the condyle between titanium and bioabsorbable screws with the exception of the lateral–medial direction of the condylar centre (P = 0.042). The directional vector components were stable, regardless of mandibular setback.ConclusionIn 3D vector analysis, bioabsorbable screw fixation in SSRO with distal segment osteotomy shows clinically acceptable postoperative condylar position stability.     

Association between temporomandibular joint disc position evaluated by magnetic resonance imaging and mandibular condyle inclination evaluated by computed tomography

Temporomandibular joint disc displacement is common in the world's population and could be associated with bone and functional characteristics of the temporomandibular joint. The aim of these study was to analyse the association between temporomandibular joint disc position evaluated by magnetic resonance imaging (MRI) and the inclination of the mandibular condyle evaluated by computed tomography (CT). One hundred and seventy temporomandibular joints (TMJ) were retrospectively analysed. The temporomandibular disc position was evaluated by MRI and classified into three types: normal (N), disc displacement with reduction (DDWR) and disc displacement without reduction (DDWoR). The mandibular condyle measurements evaluated by CT included horizontal, sagittal and coronal inclination. ANOVA followed by post hoc Tukey's test was used to evaluate the interaction between condylar inclination and disc position. There was an association between disc position and the horizontal and sagittal condylar inclination (P < .05). There are statistically significant differences in the mean of horizontal and sagittal inclination of the mandibular condyle between the DDWoR and the other disc positions (P = .002 and P = .004). Disc position was not statistical associated with coronal inclination of condyle (P > .05). These results indicate that the inclination of the mandibular condyle may be different in TMJ with various disc position. A more medial horizontal inclination and a more posterior sagittal inclination of the mandibular condyle are associated with DDWoR.     

A Comparison of the Change in Mandibular Condyle/Fossa Relationship with the Use of Anatomic Teeth and Semi-anatomic Teeth in Complete Denture Prosthesis

The association between dental occlusion and mandibular condyle/fossa relation has long been debated and still remains one of the most controversial issues in Prosthodontics. The aim of the study was to evaluate the effect of two different tooth forms on the condyle/fossa relation recorded during jaw relation process. Twenty edentulous patients were selected with good neuromuscular control. For each patient two pairs of dentures were fabricated with anatomic teeth and semi-anatomic teeth. Condylar position was recorded using a digital volume tomography (DVT) following the process of jaw relation (following extra oral tracing). Subsequent laboratory remounting, the denture insertion was done and DVTs were taken again for both the dentures separately. Two methods were used to evaluate the condyle/fossa relation viz. (1) Zhang’s method (2) Brewka’s method. The obtained values were then subjected to statistical analysis. The statistical significance was set as at 0.05 %. The mandibular concentricity were analysed during the process of jaw relation and after the insertion of dentures with the two different tooth forms. Statistical analysis indicated that no statistically significant difference of the influence of different posterior tooth forms on the condyle/fossa relation recorded during jaw relation (p < 0.05). Thus within limitations of this study it was concluded that the condyle/fossa relation established during jaw relation does not change with the change in posterior tooth form used.     

Panoramic radiographic evaluation of the mandibular morphological changes in elderly dentate and edentulous subjects

Abstract

Objective. The aim of the present study was to analyze the changes in the gonial angle, ramus height, condyle height and cortical bone thickness in relation to gender and dental status in elderly patients. Materials and methods. The study population comprised 240 patients (age ranged from 60–69 years) who had digital panoramic radiographs taken for various purposes. One group consisted of 120 patients, 60 men and 60 women, who had all natural teeth present except for third molars. The second group consisted of the remaining 120 patients (60 men and 60 women) who were in a completely edentulous state (maxilla and mandible). The gonial angle, ramus height, condylar height and cortical bone thickness of the mandible were measured by computer software on their panoramic radiographs. Results. Women showed larger gonial angles than men, while men had greater cortical bone thickness and ramus height (p < 0.05). However, no significant difference in condylar height was found between both genders (p > 0.05). Edentulous subjects had a larger gonial angle than dentate subjects, while dentate subjects had greater cortical bone thickness on both sides and left side of condylar height (p < 0.05). The gonial angle had statistically negative correlations with cortical bone thickness and ramus height, regardless of gender. Conclusions. The outcomes of the present study indicate that the edentulous women undergo morphological changes of the mandible influenced by the dental status more than men.     

Three-dimensional Analysis of Alveolar Bone With and Without Periodontitis

ObjectiveThe aim of this study was to investigate the alveolar bone density and thickness in Chinese participants with and without periodontitis.MethodologyThis study was retrospective and cross-sectional in nature and used cone-beam computed tomography (CBCT) to evaluate alveolar bone loss, bone density, and bone thickness around 668 mandibular molars (344 periodontally healthy teeth and 324 teeth with periodontitis). Comparative statistical tests were done related to the age, sex, tooth type, tooth side, and degree of bone loss. The significance level was set to be P < .05.ResultsThe alveolar bone density significantly differed between the healthy and periodontitis groups (mean difference = 24.4 Hounsfield units; P = .007). Similarly, the alveolar bone thickness of the healthy group was significantly higher than that of the periodontitis group (4.6 ± 1.8 mm compared to 4.2 ± 1.1 mm). Teeth in females demonstrated a significantly (P ? .001) higher bone density compared with males in both healthy and compromised groups. However, males showed a significantly (P ? .05) thicker bone of the teeth than females in relation to the healthy group. The alveolar bone density and thickness in both healthy and periodontitis groups significantly differed between the first and the second molars (P < .001). The alveolar bone thickness had a highly significant difference (P < .001) between the different degrees of bone loss.ConclusionsAlveolar bone thickness and density were reduced at periodontally diseased teeth.     

Molar Inclination and Surrounding Alveolar Bone Change Relative To the Design of Bone-borne Maxillary Expanders: A Cbct study

ObjectiveTo evaluate the molar inclination and skeletal and alveolar bone changes when comparing tooth bone-borne (MSE) and tissue bone-borne type maxillary expanders (C-expander) using cone-beam computed tomography (CBCT) in late adolescence.Materials and MethodsA sample of 48 late-adolescent patients were divided into two groups according to the type of expander: MSE group (n = 24, age = 19.2 ± 5.9 years) and C-expander group (n = 24, age = 18.1 ± 4.5 years). CBCT scans were taken before treatment and 3 months after expansion. Transverse skeletal and dental expansion, alveolar inclination, tooth axis, buccal alveolar bone height, thickness, dehiscence, and fenestration were evaluated on the maxillary first molar. Paired t-test, independent t-test, Pearson''s chi-square test, and Spearman correlation analysis were performed.ResultsThe MSE group produced greater dental expansion (P < .05), whereas skeletal expansion was similar in both groups (P = .859). The C expander group had more alveolar bone inclination change (P < .01), and the MSE group had more buccal tipping of the anchorage teeth (P < .01 or .001). Buccal alveolar bone height loss and thickness changes were greater in the MSE group (P < .01 or <.001). Formation of dehiscences was more frequent in the MSE group (P < .001), whereas for fenestrations, there were no significant differences between the two groups. Buccal bone height loss in the MSE group had a negative correlation with initial buccal bone thickness.ConclusionsThe incorporation of teeth into bone-borne expanders resulted in an increase in the severity of side effects. For patients in late adolescence, tissue bone-borne expanders offer comparable skeletal effects to tooth bone-borne expanders, with fewer dentoalveolar side effects.     

Effects of osseous structure based on three-dimensional reconstructive imaging evaluation in the assessment of temporomandibular joint disc position

Objectives

This pilot morphological study aimed to investigate the association between anterior disc displacement (ADD) and the status of the mandibular condyle and articular fossa.

Materials and methods

Thirty-four patients were divided into a normal articular disc position group and an ADD with and without reduction group. Images reconstructed were used to determine multiple group comparisons of these three different types of disc position, and the diagnostic efficacy for the morphological parameters with significant group difference was analyzed to assess.

Results

The condylar volume (CV), condylar superficial area (CSA), superior joint space (SJS), and medial joint space (MJS) all exhibited obvious changes (P < 0.05). Additionally, they all had a reliable diagnostic accuracy in differentiating between normal disc position and ADD with an AUC value from 0.723 to 0.858. Among them, the CV, SJS, and MJS (P < 0.05) had a significantly positive impact on the groups by analysis of multivariate logistic ordinal regression model.

Conclusions

The CV, CSA, SJS, and MJS are significantly associated with different disc displacement types. The condyle in ADD exhibited altered dimensions. These could be promising biometric markers for assessing ADD.

Clinical relevance

The morphological changes of mandibular condyle and glenoid fossa were significantly influenced by the status of disc displacement, and condyles with disc displacement had three-dimensionally altered condylar dimensions, irrespective of age and sex.