Comparison of T2 values of the displaced unilateral disc and retrodiscal tissue of temporomandibular joints and their implications.

Unilateral anterior disc displacement (uADD) has been shown to affect the contralateral joints qualitatively. This study aims to assess the quantitative T2 values of the articular disc and retrodiscal tissue of patients with uADD at 1.5 Tesla (T). The study included 65 uADD patients and 17 volunteers. The regions of interest on T2 maps were evaluated. The affected joints demonstrated significantly higher articular disc T2 values (31.5 ± 3.8 ms) than those of the unaffected joints (28.9 ± 4.5 ms) (P < 0.001). For retrodiscal tissue, T2 values of the unaffected (37.8 ± 5.8 ms) and affected joints (41.6 ± 7.1 ms) were significantly longer than those of normal volunteers (34.4 ± 3.2 ms) (P < 0.001). Furthermore, uADD without reduction (WOR) joints (43.3 ± 6.8 ms) showed statistically higher T2 values than the unaffected joints of both uADD with reduction (WR) (33.9 ± 3.8 ms) and uADDWOR (38.9 ± 5.8 ms), and the affected joints of uADDWR (35.8 ± 4.4 ms). The mean T2 value of the unaffected joints of uADDWOR was significantly longer than that of healthy volunteers (P < 0.001). These results provided quantitative evidence for the influence of the affected joints on the contralateral joints.

Characteristics of CBCT versus panoramic signs of the surrounding bone of molar root protrusions into the maxillary sinus.

The study aimed to (a) investigate the amount and characteristics of the surrounding bone of protruded molar roots into the maxillary sinus using cone-beam computed tomography (CBCT) and (b) assess the correlation between the amount of bone with panoramic high-risk signs. Radiographs of 408 roots protruding beyond the sinus floor were evaluated. Axial CBCT images were used to investigate then classify eight characteristics of surrounding bone: no bone; bone < half the root girth in the proximal or buccal-palatal aspect; bone covering half the root girth in the proximal or buccal-palatal aspect; bone > half the root girth in the proximal or buccal-palatal aspect; and, complete bone. These were then grouped into four degrees of bone support: no bone; bone ≤ half the root girth; bone > half the root girth; and, complete bone. Panoramic signs were subclassified as: projection of root; interruption of the sinus floor; darkening of the root; upward curving of the sinus floor; absence of periodontal ligament space; and, absence of the lamina dura. Correlation between the degree of bone and the panoramic signs was evaluated using the Chi-square or Fisher's exact tests. Positive and negative predictive values, sensitivity, specificity, accuracy, and receiver operating characteristic analysis were calculated. Complete bone support was the most common. 'Projection of root' had a high negative predictive value and sensitivity. 'Absence of the periodontal ligament space and lamina dura' had a high positive predictive value, specificity, accuracy, and area under the curve. These two signs were significantly correlated with the degree of bone support.

Non-endodontic periapical lesions clinically diagnosed as endodontic periapical lesions: A retrospective study over 15 years.

BACKGROUND: This study aimed to provide the frequency and demographic data of non-endodontic periapical lesions clinically misdiagnosed as endodontic periapical lesions from a Southeast Asian population over a 15-year period. MATERIAL AND METHODS: A retrospective study was conducted from departmental archives between 2005 and 2019. Cases clinically diagnosed as endodontic periapical lesions were retrieved. Then, cases with a histopathological diagnosis of non-endodontic periapical lesion were selected. Demographic data of non-endodontic periapical lesions were recorded. Radiographic features of cases with available radiographs were analyzed. RESULTS: Of 1,566 cases clinically diagnosed as endodontic periapical lesion, 157 cases received a histopathological diagnosis of non-endodontic origin. Eighteen different histopathological diagnoses were identified. The most frequent lesion was dentigerous cyst (n= 51, 32.48%) followed by odontogenic keratocyst (n=31, 19.75%), nasopalatine duct cyst (n=18, 11.46%) and ameloblastoma (n=15, 9.56%). Three cases of malignant tumors, including adenoid cystic carcinoma, mucoepidermoid carcinoma, and metastatic papillary thyroid carcinoma were observed. CONCLUSIONS: Non-endodontic periapical lesions constituted 10.03% of cases clinically diagnosed as endodontic periapical lesions. Histopathological examinations of non-endodontic periapical lesions revealed a variety of lesions ranging from foreign body reaction, cysts, fibro-osseous lesions, benign tumors and primary or metastatic malignant tumors. Of clinical significance is that some non-endodontic periapical lesions had different treatment modalities and prognoses compared with endodontic lesions. Therefore, dentists must be aware that periapical radiolucent lesions are not always a consequence of pulpal necrosis. Key words:Ameloblastoma, dentigerous cyst, endodontic periapical lesions, non-endodontic periapical lesions, odontogenic keratocyst.

Odontogenic keratocyst and ameloblastoma: radiographic evaluation.

OBJECTIVES: To describe the radiographic features of odontogenic keratocysts (OKCs) and ameloblastomas and to compare the radiographic findings between these 2 lesions. METHODS: Radiographs of OKCs and ameloblastomas were retrospectively reviewed. Location, border, shape, association with impacted tooth, tooth displacement, root resorption, and bone expansion were evaluated. Chi-squared or Fisher's exact tests were used for statistical analysis. A p value < 0.05 was considered to indicate statistical significance. RESULTS: One hundred OKCs and 101 ameloblastomas were reviewed. The ratios of maxilla to mandible were 1:1.4 and 1:9.1 in OKCs and ameloblastomas, respectively. All evaluated features significantly differed between OKCs and ameloblastomas (p ≤ 0.001). Most OKCs showed smooth border (60%) and unilocular shape (82%), while most ameloblastomas showed scalloped border (77.2%) and multilocular shape (68.3%). Association with impacted tooth was found in 47% of OKCs and 18.8% of ameloblastomas. Adjacent tooth displacement was found in 33.7% of OKCs and 55.8% of ameloblastomas. Root resorption was more common in ameloblastomas (66.7%) than in OKCs (7%). Bone expansion was also more common in ameloblastomas (96.3%) than in OKCs (63.6%). CONCLUSION: A unilocular radiolucent lesion with smooth border, no adjacent tooth displacement, no root resorption and causing mild or no bone expansion is suggestive of an OKC rather than an ameloblastoma.

A Pilot Study of Small-Diameter One-Piece Ceramic Implants Placed in Anterior Regions: Clinical and Esthetic Outcomes at 1-Year Follow-up.

PURPOSE: The aim of this study was to evaluate the clinical, esthetic, and patient-reported outcomes of one-piece zirconia implants placed in incisal areas using digital surgical templates after 1 year of follow-up. MATERIALS AND METHODS: Patients who had lost an anterior tooth received a 3.3-mm-diameter zirconia implant placed by computer-guided surgery. Implant survival and soft tissue conditions were assessed periodically 1 week, 3 months, 6 months, and 1 year after loading. Standardized radiographs were taken at definitive prosthesis insertion and 1 year postloading to evaluate peri-implant bone loss. Additionally, the esthetic outcomes and patient-reported outcomes were also investigated. RESULTS: Twenty zirconia implants were placed in 20 patients with no implants lost, resulting in 100% survival rates. A minor change in the mean marginal bone level (0.14 ± 0.87 mm) was found between definitive prosthetic loading and 12 months later. Peri-implant soft tissue remained stable throughout the observation period. The mean Pink Esthetic Score and White Esthetic Score were 12.05 and 8.60, respectively, while the mean Gingival Papilla Index scores were 1.55 at the mesial papilla and 1.65 at the distal papilla at the 1-year follow-up. The mean visual analog scale scores for patient perception of the overall process, speech, mastication, and esthetics were 93.3 ± 7.8, 95.1 ± 5.3, 93.6 ± 7.6, and 94.5 ± 6.2 mm, respectively. CONCLUSION: For the 1-year results, 3.3-mm-diameter one-piece ceramic implants placed by computer-guided surgery showed favorable clinical performances with no failure when used for single-tooth replacement in anterior regions.

Accuracy of computer-guided implantation in the placement of one-piece ceramic dental implants in the anterior region: A prospective clinical study.

PURPOSE: Placement of one-piece ceramic dental implants requires precision, which can be enhanced by using a computer-guided system. This prospective clinical study examines the accuracy of partially guided implantation in the placement of one-piece ceramic implants in the anterior region. MATERIALS AND METHODS: One-piece ceramic dental implants were placed in 20 patients who were missing a central or lateral incisor. Partially guided dental implant placements were performed in all cases. The deviations in the implant positions were analyzed by superimposing post-operative cone beam computed tomography images over pre-operative treatment planning images. The results were reported as deviations (mean ± standard deviation) for three aspects (3D offset, mesio-distal, labio-lingual, and apico-coronal) and in three dimensions (the angle, coronal, and apical parts). RESULTS: Implants were successfully placed in 20 patients. The mean angular deviation was 4.23±1.84°, whereas the mean coronal 3D offset was 0.98±0.48 mm, and the mean apical 3D offset was 1.57±0.46 mm. CONCLUSIONS: A prospective clinical study involving 20 patients was conducted to measure the accuracy of computer-guided implantation of one-piece ceramic dental implants. Accuracy was determined by comparing the planned implant position to the actual position. Greater accuracy can be expected at the coronal part than at the apical part. The coronal 3D offset was found to be the most accurate.

T2 relaxation times of the retrodiscal tissue in patients with temporomandibular joint disorders and in healthy volunteers: a comparative study.

OBJECTIVE: The aims of this study were to compare the temporomandibular joint (TMJ) retrodiscal tissue T2 relaxation times between patients with temporomandibular disorders (TMDs) and asymptomatic volunteers and to assess the diagnostic potential of this approach. STUDY DESIGN: Patients with TMD (n = 173) and asymptomatic volunteers (n = 17) were examined by using a 1.5-T magnetic resonance scanner. The imaging protocol consisted of oblique sagittal, T2-weighted, 8-echo fast spin echo sequences in the closed mouth position. Retrodiscal tissue T2 relaxation times were obtained. Additionally, disc location and reduction, disc configuration, joint effusion, osteoarthritis, and bone edema or osteonecrosis were classified using MRI scans. The T2 relaxation times of each group were statistically compared. RESULTS: Retrodiscal tissue T2 relaxation times were significantly longer in patient groups than in asymptomatic volunteers (P < .01). T2 relaxation times were significantly longer in all of the morphologic categories. The most important variables affecting retrodiscal tissue T2 relaxation times were disc configuration, joint effusion, and osteoarthritis. CONCLUSIONS: Retrodiscal tissue T2 relaxation times of patients with TMD were significantly longer than those of healthy volunteers. This finding may lead to the development of a diagnostic marker to aid in the early detection of TMDs.

Branching patterns of the inferior alveolar canal in a Thai population: a novel classification using cone beam computed tomography.

OBJECTIVE: This aim of this study was to determine the prevalence and branching patterns of the inferior alveolar canal (IAC) in premolar and molar areas using cone beam computed tomography (CBCT). METHOD AND MATERIALS: CBCT volumes from partially or fully edentulous premolar and molar areas were investigated retrospectively. The presence of such branches with their patterns, sides, and areas, as well as the sex of the patient, were recorded by two observers and analyzed statistically. The branching patterns were initially classified into three types: A, superior type; B, forward type; and C, plexus type. During the investigation, an additional type was found in the premolar area and was classified as type D, an anterior extension type. RESULTS: In total, 243 mandibular sites in 176 subjects were included. Among them, 106 sites displayed branches (43.62%). In the premolar area, most branches were of the anterior extension type (D, 33%), followed by the superior and plexus types (A and C, respectively, 29%), and the forward type (B, 9%). In the molar area, the plexus type was the most common finding (C, 39%), followed by the superior type (A, 32%) and the forward type (B, 29%). Branches in the molar area were significantly more frequent in men than in women (P = .011). CONCLUSION: IAC branches with four branching patterns in the premolar and molar areas are not rare and could be detected by CBCT. Clinicians should be aware of these branches during surgical procedures concerning the posterior mandible.

The retromolar canal and its variations: Classification using cone beam computed tomography.

OBJECTIVE: To determine the prevalence of the retromolar canal and its various patterns using cone beam computed tomography (CBCT). METHOD AND MATERIALS: CBCT images with the presence of mandibular third molars from August 2013 to May 2015 were retrospectively investigated. The presence of retromolar canal, its patterns, sides, as well as gender were evaluated by two observers. The pattern of retromolar canal was initially classified into three types: Type A, superior type; Type B, radicular-retromolar type; and Type C, dental type. During the investigation, two additional types were found and further classified: Type D, plexus type; and Type E, forward type. The distribution of retromolar canals between genders and sides was statistically analyzed with Pearson's chi-square test. RESULTS: A total of 201 mandibular sites in 156 subjects (99 women, 57 men) were included. Among them, 128 sites had retromolar canals (63.68%). The presence of retromolar canal was not statistically related to gender or side. Most of the retromolar canals were the radicular-retromolar type (Type B, 38.10%), followed by the superior type (Type A, 29.93%), dental type (Type C, 19.73%), plexus type (Type D, 6.80%), and forward type (Type E, 5.44%). CONCLUSION: There was a high frequency of retromolar canals and these could be classified into five patterns. The clinician should be aware of this anatomical structure when performing surgical procedures involving the retromolar area.