Fractal analysis of the mandible cortical bone: correlation among fractal dimension values obtained by two processing methods from periapical radiograph and micro-computed tomography with cone-beam computed tomography.

The objectives of the present study were to assess Fractal Dimension (FD) values in the mandible cortical bone obtained from digital periapical radiographs (DPR), high-resolution microtomography (µCT), and cone-beam computed tomography (CBCT), by two processing methods: binarization (FD.b) and grayscale-based method (FD.f) and, finally, to identify the correlation among these values with other micro-architectural parameters. For this, a prospective study was conducted on 18 healthy individuals (mean age 23 ± 2.4 years old) who underwent third molar extraction. Pre-operative CBCT scans were conducted, bone fragments were removed from the retro-molar region, and DPR and µCT were performed on those bone samples. FD.b and FD.f values were calculated using three parasagittal sections for CBCT, one image for DPR, and three sections for µCT. The 3D bone microarchitecture was analyzed in µCT (voxel size: 19 µm). As a result, FD.b mean values of 1.55 ± 0.02 and 1.80 ± 0.01 were obtained for CBCT and µCT, respectively. Furthermore, FD.f mean values of 1.22 ± 0.12 for DPR, 0.99 ± 0.04 for CBCT, and 1.30 ± 0.07 for µCT were obtained. Both FD.b and FD.f values showed a good agreement. FD.f was negatively correlated with the standard deviation of the mean gray value (p = 0.003) for DPR and intra-cortical bone surface (p = 0.02) for µCT. In conclusion, image processing with or without binarization revealed different values for FD, although showing agreement. The grayscale-based method retrieved FD values correlated with the gray levels and the cortical porous network, which means that FD can be a valuable index for mandibular cortical bone evaluation. FD is associated with mineralization and microarchitecture. Nevertheless, there was no correlation between FD values obtained from low- (DPR) and high-resolution (µCT) X-ray modalities with FD obtained from the in vivo CBCT.

Evaluation of the dimensions, morphology, and position of the mandibular condyles in individuals with neurofibromatosis 1: a case-control study.

OBJECTIVES: The aim of this study was to evaluate the mandibular condyles of neurofibromatosis 1 (NF1) individuals without facial plexiform neurofibroma using cone beam computed tomography images. MATERIALS AND METHODS: Eighty cone beam computed tomography scans (160 mandibular condyles) were analyzed: 40 from NF1 individuals (study group) and 40 from individuals without NF1 (control group). The anteroposterior and mediolateral dimensions, height, and volume of the mandibular condyles were measured. The mandibular condyles were classified according to their morphology: healthy (absence of morphological changes), with flattening (loss of rounded contour of at least one of the surfaces), with erosion (loss of continuity of the cortical bone), with osteophyte (exophytic formation of the condyle surface), and with sclerosis (any increase in the cortical thickness in the load-bearing areas). Furthermore, the position of the mandibular condyles in relation to the joint fossa in an anteroposterior view was classified as anterior, concentric, or posterior. RESULTS: The study group had a higher anteroposterior dimension of the mandibular condyles compared with the control group (p < 0.05). There were no differences in condylar morphology and position between both groups (p > 0.05). The morphological alterations were not associated with sex or age in any group evaluated (p > 0.05). For both groups, the concentric position was the most common. For the study group, there was a significant difference in the condylar position between the sides (p < 0.05). CONCLUSIONS: NF1 individuals without facial plexiform neurofibroma present a high prevalence of condyles with a large anteroposterior dimension and asymmetric position in the joint fossa. However, no morphological and volumetric changes were observed in the mandibular condyles of them. CLINICAL RELEVANCE: The knowledge of the TMJ alterations in individuals with NF1 is important to establish an evaluation protocol, which would allow early intervention if indicated.

Bone and gingival tissue thicknesses of maxillary anterior teeth with and without a metal post: a cone beam computed tomographic study.

The objective of this retrospective study was to evaluate buccal bone and gingival thickness measurements obtained from cone beam computed tomographic (CBCT) images of maxillary anterior teeth with and without metal posts. A convenience sample of 71 CBCT images of healthy maxillary anterior teeth and 61 CBCT images of maxillary anterior teeth with a metal post were selected from a database. Eight tomographic measurements (4 bone thicknesses and 4 gingival thicknesses) were performed in the parasagittal section of each tooth, perpendicular to the tooth axis. The Mann-Whitney U test was used to compare these thicknesses, and the Spearman correlation coefficient was calculated for correlation of age with sex. Statistically significant differences were observed for almost all measurements (P < 0.05); the CBCT images of teeth with metal posts displayed lower bone thickness values and higher gingival thickness values. No statistically significant correlations were observed between the thickness measurements and age. However, significantly higher bone thickness values were observed in men (P < 0.05). Cone beam computed tomographic images of teeth with metal posts showed differences in mean bone and gingival measurements compared to teeth without metal posts, suggesting a possible interference of metal artifacts.

Artifacts caused by titanium implants in CBCT images of the mandible: an experimental study.

This study evaluated the quantity of metal artifacts produced by dental implants placed in different mandibular regions using various cone beam computed tomography (CBCT) protocols. Titanium implants were placed in 4 regions (incisor, canine, premolar, and molar) of an artificial mandible and subjected to CBCT examinations with the mandibular model placed in different positions within the field of view (FOV) and imaged with different FOV and voxel sizes. An axial section of the cervical region of each implant was selected for artifact quantification. The artifacts were measured by normalizing the actual standard deviation (ASD) of the voxel values. Kruskal-Wallis and Student-Newman-Keuls tests were used to compare the tooth regions and the different positions of the mandible. The Wilcoxon test was used to compare changes in FOV and voxel size. The intraobserver agreement was calculated using the intraclass correlation coefficient. The significance level was 5%. The incisor region showed significantly more artifacts than other regions (P = 0.0315). No statistically significant difference was found when the position of the mandible varied within the FOV (P = 0.7418). Smaller FOV and smaller voxels produced more artifacts (P < 0.0001). The quantity of metal artifacts was affected by FOV and voxel size as well as by anatomical region. Variation of the mandible location within the FOV did not affect the artifacts as defined by the normalized ASD of the voxel values.

Classification of the midpalatal suture maturation in individuals older than 15 years: a cone beam computed tomographic study.

PURPOSE: The aim of this study was to classify the maturation of the midpalatal suture (MPS) in a sample of individuals aged 15 years and older. METHODS: Tomographic images in axial sections of the MPS of 289 female individuals and 198 male individuals aged between 15 and 40 years were analyzed and classified in stages of maturation (A, B, C, D, and E), stage A represents the earliest maturation stage of the suture and in stage E the fusion of the MPS has occurred in the maxilla. The Kruskal-Wallis and Student-Newman-Kells tests were used to compare the chronological ages among different maturation stages. Spearman's correlation coefficient was used to assess the correlation between patient's age and the maturation stages of the MPS. RESULTS: Stage A was not observed in the sample. Stages B and C represent, respectively, 1.03% and 34.09% of the sample, stage D was found in 16.63% of the sample while stage E was the most prevalent stage found (48.25%). For females, it was revealed no statistically significant difference in the mean ages among stages C, D and E (p = 0.4753). For males, a statistically significant difference was observed, with the mean age of individuals in stages D and E of the MPS maturation higher than in other stages (p = 0.0001). There was a significant, but weak, correlation between patient's age and the maturation stages of the suture (rs = 0.11/p = 0.01). CONCLUSION: No individuals in stage A of suture maturation were found and stage B was identified in only 1% of the sample. The majority of the patients (64.88%) presented at least partial fusion of the MPS (stages D and E).

Relationship of maxillary posterior roots to the maxillary sinus and cortical bone: a cone beam computed tomographic study.

This study evaluated the relationship between the apices of maxillary posterior teeth (second premolar, first molar, and second molar) and the maxillary sinus floor (MSF) and maxillary cortical bone (MCB). Cone beam computed tomographic (CBCT) scanning was used to analyze 1660 roots from 678 teeth and determine the shortest distance between the root apex and MSF and between the root apex and buccal and palatal cortices of maxillary bone. The root apices were classified based on their relationship to the MSF: type 1, the root apex protruded into the maxillary sinus; type 2, the root apex was from 0 mm (touching the MSF) to 1 mm below the MSF; and type 3, the root apex was greater than 1 mm below the MSF. As the age of the subjects increased (older than 40 years), there was a significantly greater proximity of the teeth to the MCB (P < 0.05) and less proximity of second molars to the MSF (P = 0.005). First and second molars each presented a high prevalence of root apices that protruded into the maxillary sinus (type 1), 47.8% and 43.8%, respectively. Second premolars were more frequently classified as type 3 (71.7%) than first and second molars. The mesiobuccal root of the maxillary second molar was the root closest to the MSF, while the maxillary first molar was the tooth closest to the MCB.

Anatomical evaluation of the relationship between the maxillary posterior teeth and maxillary sinus.

Knowledge of the anatomical relationships between the maxillary sinus (MS) and posterior teeth is important to prevent complications when endodontic or oral surgical procedures are performed. The aim of this study was to evaluate the relationships between the root apices of maxillary posterior teeth and the MS floor. Three oral radiologists evaluated 851 posterior teeth (1969 roots) imaged with cone beam computed tomography. The roots were analyzed individually in parasagittal sections, on which the most superior point of the apex was observed. A qualitative evaluation was performed, and each root was assigned a proximity score: 1, root invaginating the MS; 2, root in close contact with the MS floor; 3, root with no relationship with the MS; and 4, root with a measurable proximity to the MS. For roots classified as score 4, the distance to the MS floor was measured (quantitative analysis). Student t tests, 1-way analysis of variance, and simple linear regression analysis were performed (P < 0.05). The qualitative analysis revealed that the mesiobuccal root of the second molar had a pronounced proximity to the MS. The quantitative analysis revealed no differences in distance to the MS between right and left posterior teeth or between the different roots of the same tooth. In relation to the MS, the second molar was positioned closest, followed by the first molar, second premolar, and first premolar. Except for the comparison between mean distances of the second premolar and first molar (P = 0.11), the differences between groups of teeth were statistically significant (P < 0.05). Simple linear regression analysis showed that the more posterior the tooth was in relation to the midline, the shorter the mean distance from the root apex to the MS floor (P < 0.05). The mesiobuccal roots of second molars were closest to the MS. Second molars exhibited the shortest distances between their root apices and the MS and the greatest number of roots that were invaginating or in close contact with the MS. Therefore, second molars require special attention when endodontic or oral surgical approaches involve those regions.

Association between bruxism and temporomandibular disorders in children: A systematic review and meta-analysis.

BACKGROUND: Bruxism in children and its relation to the development of temporomandibular disorders (TMD) has not been clearly determined yet. AIM: The objective of this systematic review was to evaluate the possible association between bruxism and TMD in children. DESIGN: Seven databases were searched, and 497 articles were assessed. Methodological quality was assessed through Newcastle-Ottawa Scale. The meta-analysis was performed with the articles in which extraction of data was possible and the summary effect measure through odds ratio (OR) and respective 95% confidence intervals (CIs). Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) was used to assess the certainty of evidence. RESULTS: Ten cross-sectional studies were included in the systematic review. Of these, 8 showed a statistically significant association between bruxism and TMD. Seven studies however presented a high risk of bias. The meta-analysis was performed with 3 articles and obtained an OR of 2.97 (95% CI ranging from 1.72-5.15), indicating that children with bruxism are 2.97 times more likely to present TMD, with very low level of certainty defined by GRADE. CONCLUSIONS: Although the studies showed high risk of bias, the qualitative analysis of individual studies showed that the children with bruxism have greater chance of developing TMD.

Fatigue Behavior of Different CAD/CAM Materials for Monolithic, Implant-Supported Molar Crowns.

PURPOSE: To evaluate the fracture resistance after the thermal and mechanical fatigue of feldspathic, lithium disilicate, and resin-modified CAD/CAM monolithic crowns cemented onto a universal post abutment. MATERIALS AND METHODS: A right second mandibular molar was designed in CAD/CAM software, and 30 crowns were machined using three different materials (n = 10): feldspathic ceramic, finished only with a glaze cycle (G1); lithium disilicate, sintered and finished with a glaze cycle (G2); and resin, modified by nanoceramic and finished with rubber (G3). All crowns were cemented under a constant 50 N load, the excess cement was removed, and the crowns were light-cured for 30 seconds. After being immersed in deionized water for 7 days, the crowns were submitted to thermal cycling, which consisted of varying the temperature from 2 to 50°C for 350,000 cycles, and mechanical cycling in a fatigue simulator, where a 250 N load was applied for 1,000,000 cycles at 2 Hz. The resistance of each crown was verified in a compression-to-failure test at 1 mm/min in a universal test machine. The groups were compared using one-way ANOVA with a Bonferroni post hoc test and Weibull statistics. RESULTS: The resin-modified group was the least resistant group (1755 ± 124 N), followed by the feldspathic (2147 ± 412 N) and lithium disilicate groups (2804 ± 303 N). The Weibull statistics demonstrated that lithium disilicate is the most reliable material and has the lowest fracture probability. CONCLUSIONS: It was possible to conclude that all of the tested CAD/CAM materials can be used as monolithic, implant-supported molar crowns.

Double mandibular canal and triple mental foramina: detection of multiple anatomical variations in a single patient.

Having complete information about a patient's mandibular canal and mental foramen is fundamental to performing safer procedures and avoiding intraoperative and postoperative complications. Cone beam computed tomography (CBCT) produces accurate images for the analysis of maxillomandibular bone structures and is widely used in dentistry. The aim of this study is to report a case of mandibular bifid canal associated with triple mental foramina that was revealed with CBCT images. A 45-year-old woman was referred for a CBCT scan of remaining bone quantity to assist in preoperative implant planning. The patient had reported problems related to anesthesia during extraction of the mandibular right second and third molars. Examination showed bilateral bifurcation of the mandibular canal, from the mandibular foramen to the gonial angle. In addition, exteriorization of the mandibular canal was noticed in 3 regions; that is, there were 3 distinct mental foramina. Clinicians must be aware of these anatomical variations in the mandibular region during dental procedures to avoid complications such as difficulty in obtaining anesthesia or postoperative sensory dysfunction.

Zirconia Abutment Supporting All Ceramic Crowns in the Esthetic Zone: Interim Results of a Prospective Study.

AIM: This prospective study evaluated peri-implant tissues around all-ceramic crowns fabricated using CAD/CAM technology. MATERIAL AND METHODS: Twenty-five patients received pre-fabricated zirconia implant abutments with CAD/CAM zirconia copings in the esthetic zone. Implants were evaluated at baseline, and at 3 and 6 months in function. RESULTS: Radiographic analyzes showed stable bone crest around the implants. Esthetics were more favorable as time lapsed (p > 0.05). Bleeding Index was constant in all time intervals. Plaque index reduced from 3 to 6 months. CONCLUSION: The all-ceramic CAD/CAM crowns were clinically, radiographically and esthetically stable during the study period.

Development of estimation models of bone height considering the potential presence of anterior extension of the mandibular canal.

PURPOSE: To evaluate the presence of the anterior extension (AE) of the mandibular canal and to measure the bone height (BH) at different points along the extension. MATERIALS AND METHODS: Cone-beam computed tomography examinations of 108 patients were bilaterally evaluated regarding the presence of the AE, and linear measurements of the AE and BH were obtained. For comparisons between sides and genders, Student t test was applied. Variations in BH measurements were assessed by a 2-way analysis of variance. Through a simple linear regression analysis, formulas were determined for calculations of the BH in the AE. RESULTS: A right AE was detected in 76.9% and left AE in 77.8% of the samples. In the majority of the cases, the extension was of the rectilinear type. The mean length of the AE was 8.5 mm, and there was no statistically significant difference observed in relation to gender or side. It was observed that the BH increases as it approaches the midline. CONCLUSION: The AE of the mandibular canal must be evaluated during presurgical planning. The formulae presented in this study provide a method to calculate BH values in the interforaminal region and can be used to assist in presurgical planning, especially in the cases in which the identification of the hipodense site, which corresponds to the AE, is not evident.

Assessing peri-implant bone microarchitecture: conventional vs. osseodensification drilling - ex vivo analysis.

The aim was to evaluate primary implant stability and bone microarchitecture in two drilling situations, by comparing the conventional technique (CT) and osseodensification (OD) (Versah Burs - Jackson - Mississippi - USA). The implant insertion torque (IT), implant stability quotient (ISQ), and the peri-implant trabecular microstructure were assessed on bone fragments obtained from pig's tibia (n=12), divided between CT (n=6) and OD (n=6). After the drilling procedure, the implants were installed (3.5x8.5 mm, Epikut - SIN - São Paulo - Brazil). The IT and ISQ were measured using a digital torque wrench and resonance frequency analysis. Then, the bone fragments containing the implants were removed with a trephine and analyzed by Microtomography (µCT, 8.0 µm). The comparison between groups was performed using the unpaired t-test (α=0.05). The results revealed that OD promotes a higher insertion torque (CT: 7.67±2.44 Ncm; OD: 19.78±5.26 Ncm) (p=0.0005), although ISQ was not different (CT: 61.33±4.66; OD: 63.25±4.58) (p=0.48). There was a significant increase in peri-implant bone volume (CT: 23.17±3.39 mm3; OD: 32.01±5.75 mm3) (p=0.008), and trabecular parameters: separation (CT: 0.4357±0.03 mm; OD: 0.3865±0.04 mm) (p=0.0449), number (CT: 1.626±0.18 1/mm; OD: 1.946±0.13 1/mm) (p=0.007), and thickness (CT: 0.1130±0.009 mm; OD: 0.1328±0.015 mm) (p=0.02). Structure model index (SMI) data demonstrate no significant differences between groups (CT: 1.7±0.2; OD: 1.4±0.4) (p=0.12). In conclusion, OD increases the insertion torque values and promotes beneficial changes regarding bone microarchitecture compared with CT, revealing more peri-implant bone volume with consequent higher primary stability.

Overweight/obesity and dental caries in Brazilian children and adolescents: a systematic review and meta-analysis.

This review aimed to assess the association between overweight/obesity and dental caries in Brazilian children/adolescents. Searches were performed in the Web of Science, Scopus, Cochrane, PubMed, Embase and SciELO, Lilacs and Open Grey literature databases up to June 2022. The Joanna Briggs Institute checklist for analytical cross-sectional studies, the checklist for cohort studies, and the checklist for case-control studies were used. A total of 41 publications were included, and 15 meta-analyses were performed. The authors analyzed the differences in weighted mean difference (MD) and odds ratios (OR), and their corresponding confidence intervals (CI) (95%) for dental caries among eutrophic and obese and/or overweight children/adolescents. Meta-analyses showed that there was no association between overweight and/or obesity and dental caries in Brazilian children/adolescents for most anthropometric reference curves using BMI (Body Mass Index). A greater experience of dental caries was associated with well-nourished adolescents in permanent dentition, compared with obese individuals in the same dentition, as classified by the CDC 2000 curve (OR = 2.53, 95% CI;1.49-4.29; p = 0.0006; I2 = 0%) in dichotomous outcome studies, and (MD = 0.61, 95%CI: 0.08-1.15; p = 0.02; I2 = 0%) in continuous studies. The strength of the evidence of the results was classified as very low, low or moderate. It was concluded that there is no association between overweight and/or obesity and dental caries in Brazilian children/adolescents for most anthropometric reference curves using BMI. A greater experience of dental caries was associated with well-nourished adolescents in permanent dentition, compared with obese individuals in the same dentition, as classified by the CDC 2000 curve.

Impacts of the COVID-19 pandemic on the routine of Brazilian oral radiologists.

OBJECTIVE: To analyze the challenges and impacts of COVID-19 on the routine of Brazilian oral radiologists regarding changes in biosafety protocols, number of patients and staff, the flow of acquisition, and availability of images. METHODS: Structured digital questionnaires with questions related to the impacts of the COVID-19 pandemic on Oral Radiology were applied and analyzed. Descriptive statistical analysis was used to describe the items included in the survey, and means and standard deviations were calculated to describe continuous variables and frequency percentages to describe categorical data. RESULTS: A high number of Brazilian oral radiologists continued to work in the pandemic period, with little or no change in their working hours. Digital flow and teleradiology are in most of their workplaces and the changes imposed by the pandemic will be incorporated and permanent, according to most of the participants in this study. CONCLUSIONS: The COVID-19 pandemic brought important impacts on radiology clinics, with changes in the flow of patients, in the service and in the type of exam performed. In addition, adaptation to biosafety standards became necessary, with a significant increase in spending on personal protective equipment.

Fractal dimension, lacunarity, and cortical thickness in the mandible: Analyzing differences between healthy men and women with cone-beam computed tomography.

Purpose: The objective of this study was to assess the fractal dimension, lacunarity, trabecular microarchitecture parameters, and cortical linear measurements in the mandibles of male and female individuals to identify differences between them. Materials and Methods: In total, 116 cone-beam computed tomography scans of healthy individuals of different ages (57 men and 59 women, aged between 20 and 60 years) were selected. The following bone parameters were measured: 1) buccal, lingual, and basal cortical bone thickness in 5 standard parasagittal sections (the midline, the left and right sides of the lower lateral incisors, and the left and right sides of the lower canines); 2) the bone volume fraction of 10 sequential axial sections from each patient by creating a volume of interest in the area between the lower canines; and 3) fractal dimension and lacunarity using grayscale images of the same region of the volume of interest in the anterior mandible. Spearman correlation coefficients and the Mann-Whitney test were used. Results: A significant and positive correlation was found between age and cortical thickness, especially in the region of the central incisors. Significant differences between sexes in terms of fractal dimension, lacunarity, and bone volume were found. Women revealed lower fractal dimension values and higher lacunarity and bone volume ratio values than men. Conclusion: Fractal dimension, lacunarity, trabecular bone volume, and cortical thickness were different between men and women of different ages.

MRI changes and clinical characteristics in temporomandibular joints with displacement of the articular disk without reduction - a cross-sectional observational study.

OBJECTIVES: This study examined changes in magnetic resonance imaging (MRI) of temporomandibular joints (TMJ) with anterior displacement disk without reduction (DDwoR) and its correlation to clinical symptoms. METHODS: 190 individuals with DDwoR were evaluated according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and MRI. Pain's chronicity/intensity and limited mouth opening (locking) were correlated with: TMJ degeneration (MRI T1), effusion (T2), disc's shape and position (proton density). RESULTS: In 103 TMJ with DDwoR, hemiconvex shape (41.6%), sclerosis (45.6%) and mild effusion (47.6%) were the most prevalent findings. There was not association (p > .05) between: different DDwoR positions with pain's intensity/chronicity; effusion with locking. Disk deformation was associated with degeneration (p = .034) and pain's intensity (p = .006). Locking was associated with degeneration (p = .05). CONCLUSIONS: Condylar osteodegeneration is often related to DDwoR. Locking by DDwoR is associated with severe levels of chronic pain and articular disk deformation.

Assessment of marginal gaps and image quality of crowns made of two different restorative materials: An in vitro study using CBCT images.

Background: The present study assessed the quality of images and the presence of marginal gaps on cone-beam computed tomography (CBCT) images of teeth restored with all-ceramic and metal-ceramic crowns and compared the gap sizes observed on CBCT images with those obtained on micro-CT images. Methods: Thirty teeth restored with metal-ceramic and all-ceramic crowns, properly adapted and with gaps of 0.30 and 0.50 mm, were submitted to micro-CT and CBCT scans. Linear measurements corresponding to the marginal gap (MG) and the absolute marginal discrepancy (AMD) were obtained. The objective assessment of the quality of CBCT images was performed using the contrast-to-noise ratio (CNR), and the subjective assessment was defined by the diagnoses made by five examiners regarding the presence or absence of gaps. Results: The measurements were always higher for CBCT, with a significant difference regarding AMD. No significant difference in image quality was observed using CNR between the crowns tested. Low accuracy and sensitivity values could be observed for both crowns. Conclusion: Marginal mismatch measures were overestimated in CBCT images. No difference in image quality was observed between the crowns. The correct diagnosis of gaps was considered low, irrespective of crown type and gap size.

Clinical and tomography evaluation of periodontal phenotypes of Brazilian dental students.

BACKGROUND: The periodontal phenotype (PP) plays an important role in the function, esthetics, and maintenance of periodontal health and has a great influence in periodontal, restorative, and dental implant therapies. AIM: The aim of this study was to conduct a clinical evaluation of the PP and its morphometric variations through the cone-beam computed tomography (CBCT), from dentistry students with periodontal health. MATERIALS AND METHODS: Sixty students were examined, and the clinical parameters of probing depth and width of keratinized tissue (WKT) in the upper anterior segment were accessed. The gingival thickness was evaluated as thick or thin, through the translucency of the periodontal probe through the marginal gingiva. By convenience sample, 13 students were selected to assess bone thickness and gingival thickness and biological width through the previous CBCT examination. RESULTS: The most prevalent PP, according to the classification by De Rouck et al., was the thick scalloped (55%), and using the classification of Kao and Pasquinelli, the thick PP was most common (73,3%). The thick PP in both the classifications was more prevalent in both genders and the WKT was significantly higher in the thick-flat scalloped PP. The bone thickness was always greater than the gingival thickness in CBCT examinations both in the measures 1 mm and 3 mm above the bone crest. The average of the biological width measurement was 2.02 mm. CONCLUSIONS: The thick PP was most prevalent in the sample studied, and the gingival thickness was always thinner than the bone thickness in the measures evaluated.

Quantitative assessment of artefacts and identification of gaps in prosthetic crowns: a comparative in vitro study between periapical radiography and CBCT images.

OBJECTIVES: To evaluate, in an in vitro study, the quantity of artefacts generated by two different restorative materials, and to determine the diagnostic accuracy of cone beam CT (CBCT) scans and periapical radiographs in identifying gaps in prosthetic crowns. METHODS: A total of 30 teeth restored with metal-ceramic (n = 15) and all-ceramic (n = 15) crowns, properly adapted and with 0.30- and 0.50 mm gaps, underwent CBCT exams (with voxel sizes of 0.25 and 0.30 mm) and periapical radiographs. The artefacts generated by two different crowns were quantified and compared by the Mann-Whitney test. In addition, five examiners evaluated the presence or absence of gaps in periapical radiographs and CBCT images. The accuracy of tests was determined by the area under the receiver operatring characteristic curve and these values were compared by using the Kruskal-Wallis test. RESULTS: There was no significant difference in artefact values between the different restorative materials and the different resolutions of CBCT images. Regarding the accuracy of the tests evaluated, periapical radiography and CBCT with voxel size 0.25 mm showed the best performance for smaller gaps (0.30 mm). For larger gaps (0.50 mm), all exams tested showed the same performance. CONCLUSIONS: Periapical radiography was still the most cost-beneficial method for the diagnosis of maladaptation in dental restorations. CBCT exams did not improve accuracy in detecting gaps in prosthetic crowns.