Confirmation of eosinophilic sialodochitis by terminal duct biopsy.

OBJECTIVE: To analyse the histopathological features of eosinophilic sialodochitis by using terminal duct biopsy. METHODS: Sixty-five patients with suspected eosinophilic sialodochitis and four with chronic obstructive sialadenitis were prospectively enrolled. Clinical features, laboratory tests and sialograms were comparatively analysed. Terminal duct biopsy of the parotid or submandibular glands was performed concomitantly with endoscopy-assisted duct dilatation to determine the histopathological features of eosinophilic sialodochitis. RESULTS: Based on eosinophil quantification, the samples of suspected patients were scored as 'definite', 'highly suspected' and 'negative' in 26 (40%), 15 (23.1%) and 24 (36.9%) cases, respectively. Gland types and peripheral blood eosinophil counts were significantly different among these three groups. The proportions of itching glands, mucus plug exudations and elevated immunoglobulin E levels were higher in the 'definite' group than in the other two groups; however, the intergroup differences were insignificant. The primary pathological features of eosinophilic sialodochitis were abundant eosinophils and lymphocytes infiltrated around the duct, degranulation of eosinophils, extensive fibrosis and scattered mastocytes. Periductal eosinophils were not found in cases of chronic obstructive sialadenitis. CONCLUSION: Our findings suggest that terminal duct biopsy is safe and valuable for the pathological confirmation of eosinophilic sialodochitis, and can be used simultaneously with endoscopy-assisted duct dilatation.

Imaging-based diagnosis and classification of radioactive iodine-induced sialadenitis.

OBJECTIVES: To establish an inflammation grading system for radioactive iodine-induced sialadenitis (RAIS) based on spiral computed tomography (CT), ultrasonography and sialography. METHODS: In all, 120 RAIS patients (18 males and 102 females) were retrospectively included. Spiral CT, ultrasonography and sialography appearances were analysed and categorized as follows: grade I, approximately normal or mild sialadenitis; grade II, moderate sialadenitis; and grade III, severe sialadenitis. Adenitis severity was analysed relative to sex, age, RAI treatment sessions and cumulative doses. RESULTS: Spiral CT showed heterogeneous (78.9%) and atrophic changes (36.8%) in the parotid glands (PGs) and duct ectasia (24.8%) in the submandibular glands (SMGs). Ultrasonography showed heterogeneous echogenicity (54.3%) and diminished gland size (30.2%) in PGs and duct ectasia in SMGs (34.7%). Sialography showed duct obliteration in 25.3% PGs and 3.2% SMGs. Statistical analysis showed good consistency among the three imaging grading results. The incidence and severity of PG lesions were significantly higher than that of SMGs (p < 0.001). As for PGs, adenitis severity was associated with both treatment sessions and cumulative doses; but in SMGs, disease severity was only related to treatment sessions. CONCLUSIONS: A grading system for severity of RAIS was established based on spiral CT, ultrasonography and sialography appearances.

Morphologic analysis of alveolar bone in maxillary and mandibular incisors on sagittal views.

PURPOSE: The aim of this study was to analyze the morphologic features of alveolus in relatively healthy maxillary and mandibular incisors using cone-beam-computed tomography (CBCT). METHODS: CBCT images of 318 patients were retrospectively acquired. Alveolar bone in incisive area was divided into: type 1 (thick), type 2 (relatively thick with mono-plate concavity), type 3 (thin with double-plate concavities), and type 4 (vulnerably thin). Alveolus prevalence and widths were analyzed statistically relative to age, gender, and molar relationship. RESULTS: Prevalence of type 1 alveolus was 78.9% in maxillary central incisors, 15.1% in maxillary lateral incisors, 24.1% in mandibular central incisors, and 5.0% in mandibular lateral incisors. Type 2 alveolus was commonly observed in the maxillary lateral incisors (82.2%), mandibular central incisors (66.2%), and mandibular lateral incisors (87.9%). Prevalence of type 3 and 4 alveoli ranged from 0.0 to 9.4%. As for maxillary central incisors, type 1 was the widest both at the alveolar crest (7.77 ± 0.58 mm) and apical area (9.05 ± 1.86 mm), while type 3 had the lowest width at the apical region (4.08 ± 0.51 mm). Among maxillary central incisors, prevalence of type 1 tended to decrease with age. At all maxillary and mandibular incisor sites, alveolus widths were significantly thicker in males than in females. At maxillary lateral incisor and mandibular incisor sites, prevalence of alveolus type was significantly different among three molar relationships. CONCLUSION: A 4-type classification system was suggested for alveolus morphology in incisive region. Identification of alveolus type might aid in the corresponding treatment.

Evaluation of Parotid Gland Function Before and After Endoscopy-Assisted Stone Removal.

PURPOSE: To quantify gland function before and after endoscopy-assisted lithectomy for patients with parotid stones and to analyze correlations among different evaluation modalities. MATERIALS AND METHODS: This study investigated 58 patients (27 men and 31 women) with a stone larger than 5 mm or multiple parotid stones who underwent successful endoscopy-assisted surgery at the authors' center from August 2007 through September 2017. Meticulous postoperative manipulations were administered routinely for 3 to 6 months to promote functional recovery of the affected gland. Gland function was evaluated preoperatively and 6 to 36 months (mean, 12 months) postoperatively by sialography, scintigraphy, and sialometry. Statistical analyses were conducted to quantify gland function recovery and to distinguish correlations among the 3 objective tests. RESULTS: Preoperative sialograms exhibited ductal ectasia at the stone site with ductal stenosis anterior to the stone (n = 53) or duct interruption at the stone site (n = 5). Postoperative sialograms of 45 patients without stones were categorized as approximately normal (type I; n = 17); showing ectasia or stenosis of the main duct without persistent contrast on the functional film (type II; n = 16); showing ectasia or stenosis of the main duct with mild contrast retention (type III; n = 6); or showing poor ductal shape with evident contrast retention (type IV; n = 6). Scintigraphy of 23 preoperative and 12 postoperative patients and sialometry of 24 preoperative and 12 postoperative patients indicated severe preoperative impairment and postoperative improvement of gland function. Postoperatively, although no relevant differences in saliva flow rate were found between the 2 sides, scintigraphy showed lower function of the affected gland compared with the control side. Statistical data showed positive correlations among the 3 methods. Sialography intuitively reflected the ductal shape, whereas sialometry and scintigraphy were more sensitive for evaluating gland function. CONCLUSION: For patients with parotid stones, minimally invasive endoscopic surgery and meticulous postoperative manipulations help preserve the glands and facilitate recovery of gland function. The 3 evaluating modalities have certain positive correlations.

Double Roots of Mandibular Premolar in Full-mouth Periapical Films.

OBJECTIVE: To evaluate the incidence of two-rooted mandibular premolar morphology using full-mouth periapical film series in a Chinese population, with particular emphasis on bilateral incidence, so as to provide a clinical anatomical basis for root canal treatment in mandibular premolars. METHODS: A total of 2015 patients who underwent dental treatment and had full mouth periapical radiographs at the Peking University School of Stomatology from April 2011 to April 2012 were enrolled in this study. Three experienced dentists reviewed the patients' periapical films and classified the root morphology of mandibular premolars bilaterally. The incidence of unilateral and bilateral double roots were recorded and calculated, including confirmed and suspected bucco-lingual root types. RESULTS: In terms of the morphology of two-rooted mandibular first premolars, of the 2015 cases with complete root formation, two-rooted first premolars were detected in 120 cases, with a total number of 159 teeth. According to the number of teeth, the overall incidence of double roots was 4.03% (159/3972). In terms of the morphology of two-rooted mandibular second premolars, of the 2015 cases with complete root formation, two-rooted second premolars were detected in 24 cases, with a total number of 33 teeth. According to the number of teeth, the overall incidence of double roots was 0.85% (33/3880). CONCLUSIONS: The roots of mandibular premolars display specific morphological patterns. Based on a large sample, we observed and calculated not only the occurrence rate of bucco-lingual and mesio-distal double roots in first and second mandibular premolars, but also the incidence of unilateral or bilateral double roots within the same mandible. These findings could provide useful information on the anatomical structure of mandibular premolars for endodontic, prosthodontic and surgical procedures, and could improve the quality of treatment and reduce complications.

[Effect of regenerative therapy for the furcation involvements of mandibular molars evaluated by cone-beam computed tomography].

OBJECTIVE: To evaluate the effect of regenerative therapy for the treatment of furcation involvements of mandibular molars with cone-beam computed tomography (CBCT). METHODS: In the study, 38 furcation involvements of mandibular molars were included and randomly divided into two groups. The experimental group accepted guided tissue regeneration and bone graft therapy, and the control group only flap surgery. The clinical examination and CBCT examination were performed at baseline and 1 year post-surgery. RESULTS: The clinical and CBCT data of both groups were not statistically different at baseline (P>0.05). At the end of 1 year post-surgery, except gingival recession, the clinical parameters of both groups were significantly improved (P<0.001). The vertical and horizontal attachment gains of the experimental group were (3.20 ± 1.82) mm and (2.05 ± 1.27) mm, respectively, and significantly higher than the changes of the control group (P<0.001). And at the end of 1 year post-surgery, the experimental group showed significantly higher bone gain at the vertical and horizontal directions compared with those of the control group: (2.82 ± 0.97) mm and (2.24 ± 0.92) mm, respectively (P<0.001). CONCLUSION: With the limitation of this study, the effect of guided tissue regeneration surgery and bone graft therapy for the treatment of furcation involvements of mandibular molars is significantly better than that of the flap surgery. CBCT can reflect the horizontal and vertical bone changes of furcation area, which is more comprehensive than traditional periapicals.

[Sialoendoscopy-assisted sialolithectomy for large parotid stones].

OBJECTIVE: To explore the clinical application of endoscope-assisted operative retrieval of large parotid stones as a minimally invasive alternative. METHODS: From January 2010 to April 2013, 6 patients (male: 5, female: 1, age from 30-62 years, and median age: 49.5 years)suffering from recurred swelling of parotid gland due to sialoliths were treated by endoscope-assisted parotid surgery in Peking University School and Hospital of Stomatology. All of the patients underwent clinical, ultrasonographic and cone-beam CT (CBCT) examinations to get the detailed information of the number, location and size of stones, which was recorded in the medical records. endoscope-assisted parotid surgery was performed under general anesthesia in all the 6 cases after the failure of basket or forcep retrieval firstly. During the operation, sialoendoscope was used to locate the stone exactly and then the calculus was exposed through a pre-auricular approach and released by incising the duct. The postoperative complications were recorded and observed during the follow-up periods. RESULTS: Preoperative radiological examinations showed that all of the sialoliths were near the hilum of parotid gland ducts in the 6 cases, which were 5-9 mm in diameter. All of the stones were removed successfully by endoscope-assisted operative retrieval. The incisions healed smoothly in all the 6 cases. There were no cases of facial nerve weakness, infection or salivary fistula. After a mean follow-up of 19 months (ranging from 6-36 months), 5 patients remained asymptomatic and 1 patient had mild obstructed or infective symptoms. The final results were satisfied. CONCLUSION: It is suggested that endoscope-assisted operative retrieval is a viable minimally invasive alternative to remove the large or recalcitrant parotid stones with a high successful rate and low complications.

Histopathological changes in salivary glands after radioactive iodine treatment for thyroid diseases.

OBJECTIVES: We aimed to evaluate the histopathological alterations in human salivary glands after radioactive iodine (RAI) treatment for thyroid diseases. STUDY DESIGN: We retrospectively selected patients with a history of RAI treatment for thyroid diseases from a database of patients who underwent surgery for oral and maxillofacial diseases and had specimens of salivary glands at Peking University School of Stomatology between December 2012 and July 2023. The patients' clinical records and histopathological slides of the salivary glands were carefully reviewed. RESULTS: Sixteen patients were included. Three symptomatic patients showed duct cell cytoplasmic vacuolization and increased numbers of disordered duct cell layers (3/3), severe duct stenosis and dilation (2/3), and exfoliated epithelial cells in the duct lumen (1/3). The glandular parenchyma showed severe acinar atrophy (2/2), fat content enhancement (2/2), and severe periductal fibrosis (3/3). Thirteen asymptomatic patients showed duct cell cytoplasmic vacuolization (5/13), acinar atrophy and increased fat content in the parenchyma (5/13), and periductal fibrosis (5/13). CONCLUSION: Main histopathologic changes in the salivary glands after RAI treatment for thyroid diseases are cytoplasmic vacuolization of duct cells, acinar atrophy, fat content enhancement, and periductal fibrosis. These changes were evident in symptomatic cases, and were also seen in some asymptomatic patients.

Diagnosis and Treatment of Radioactive Iodine-Induced Sialadenitis: A 10-Year Endoscopic Experience.

OBJECTIVES: The aim of this study was to explore the endoscopic characteristics of radioactive iodine-induced sialadenitis (RAIS), and to evaluate the treatment outcomes of endoscopic intervention for RAIS. STUDY DESIGN: Retrospective case series. METHODS: Eighty-two consecutive patients (11 males and 71 females) diagnosed as RAIS from Nov. 2012 to Sep. 2023 were retrospectively included. All patients underwent endoscopic exploration and intervention of the affected glands. The endoscopic features were collected, and treatment outcomes were followed-up and evaluated through post to pre-operative comparisons of gland status. RESULTS: Overall, endoscopic procedures were undertaken for 162 parotid glands (PGs) and 62 submandibular glands (SMGs). Endoscopy showed severe lumen stricture (49.3%) and ductal atresia (23.5%) in PGs, as well as severe stenosis of the anterior duct and ectasia of the proximal duct (59.7%) in SMGs. During a median six months' follow-up, the treatment outcomes of PGs were evaluated as "improvement" in 23.4%，"lesion maintenance" in 45.1% and "lesion aggravation" in 31.5% of the glands. As for SMGs, the treatment outcomes were scored as "improvement"in 29.0%，"lesion maintenance"in 54.8%, and"lesion aggravation"in 16.1% of the glands. No significant differences of treatment outcomes were found relative to RAI treatment sessions and cumulative dosage. CONCLUSION: RAIS is characteristic of severe lumen stricture and ductal atresia in PGs, and stenosis of the distal duct and ectasia of the proximal duct in SMGs. Endoscopy can alleviate clinical symptoms of RAIS and help to preserve the gland function. LEVEL OF EVIDENCE: 4 Laryngoscope, 2024.

Sialoendoscopy-assisted sialolithectomy for submandibular hilar calculi.

PURPOSE: To assess the clinical effects of endoscopy-assisted sialolithectomy for submandibular hilar calculi. MATERIALS AND METHODS: The present study was undertaken in 70 patients with symptomatic stones in the hilum of submandibular glands who underwent endoscopy-assisted sialolithectomy from December 2005 through March 2011 in the Peking University School and Hospital of Stomatology. The operative data were analyzed retrospectively. All patients were followed periodically postoperatively. Submandibular gland function was investigated by postoperative symptoms, clinical examinations, sialography, and scintigraphy. RESULTS: Submandibular stones were successfully removed in 65 patients, with a success rate of 92.9%. Temporary lingual nerve injury occurred in 1 patient. Two patients developed ranulae and underwent an uneventful sublingual gland excision. During a mean follow-up of 23 months (range, 6 to 55 mo), 52 of 65 patients were symptom free, whereas 11 patients complained of occasional swelling of the affected gland at mealtimes and 2 patients developed a recurrent stone. Thirty patients underwent postoperative sialography. The sialographic appearances included 4 types: 1) approximately normal; 2) the main duct was significantly dilated at the hilum, but no persistent contrast was seen on the functional film; 3) the main duct was significantly dilated in the hilar region, and persistent contrast was seen at the dilated hilum of the functional film; 4) the main duct was dilated or strictured, and persistent contrast was seen on the functional film. Three of the 4 patients who underwent scintigraphy exhibited good function. CONCLUSIONS: Sialoendoscopy-assisted sialolithectomy is a safe and effective gland-preservation technique for patients with hilar stones of the Wharton's duct.

[Method and its application of gingival thickness measurement based on cone-beam computed tomography].

OBJECTIVE: To develop a novel method for obtaining the clear visualization of the gingival profile by cone-beam computed tomography (CBCT) that consistently allows the measurements of gingival thickness and use it to explore the relationship between the gingival thickness and gingival biotype, and the gingival thickness and underlying alveolar bone thickness in the maxillary anterior region. METHODS: In this study, 15 volunteers with healthy gingiva in the maxillary anterior teeth were involved, and a special preparation was done before CBCT scans including making impression with the contrast agent. The tissue biotypes were assessed clinically with the probe, The thickness of both gingiva and bone and the gingival thickness of the cemento-enamel junction (CEJ) were measured radiographically with cone-beam computed tomography scans. All data analyses were performed using SPSS 16.0. RESULTS: The CBCT image showed clear visualization of the gingival profile. The average gingival thickness of the CEJ was (1.22±0.32) mm. A correlation was observed between the tissue biotypes and the gingival thickness (r=0.449,P<0.05). The labial gingival thickness was negative associated with the underlying bone thickness measured with CBCT in the maxillary anterior region (r=-0.31, P=0.021). CONCLUSION: A method was established for measuring gingival thickness based on cone-beam computed tomography. The gingival biotypes had a positive correlation with gingival thickness of the CEJ.

Eosinophilic Sialodochitis: A Type of Chronic Obstructive Sialadenitis Related to Allergy.

OBJECTIVES: To investigate the clinical, laboratory, radiological, histopathological, and immunohistochemical features, and the expression of allergy-related cytokines in eosinophilic sialodochitis (ES). METHODS: Thirty-eight patients diagnosed with chronic obstructive sialadenitis (COS) who had undergone glandular excision or incisional biopsy were enrolled. Seventeen patients with comorbid atopic disease and increased ductal tissue eosinophils comprised the ES group, while 21 patients comprised the COS group. The clinicopathological features and allergy-related cytokine expression were compared between groups. RESULTS: The ES group frequently involved multiple, bilateral major salivary glands, and the number of glands was significantly greater than the COS group (2.8 ± 1.1 vs. 1.2 ± 0.4, P < .001). Serum immunoglobulin (Ig) E was elevated in 91% of patients in ES group (419 ± 357 kU/L) and peripheral blood eosinophil was significantly greater compared with the COS group (7.6% ± 4.6% vs. 2.5% ± 1.4%, P < .001). Histologically, eosinophil infiltration in ES group was observed around the main and interlobular ducts (50 ± 39/high power field [HPF]). Follicular hyperplasia (76%), epithelial mucous metaplasia (82%), and mucus plugs with eosinophils (41%) were observed. IgE-positive cell count was 20.7 ± 18.3/HPF and tryptase-positive mast cell count was 23.5 ± 15.1/HPF, which was significantly greater than the respective cell counts in COS group, which mainly infiltrated around the ducts. The levels of interleukin-4, interleukin-13, and eotaxin in tissue were significantly greater in ES than the COS group. CONCLUSIONS: The clinicopathological characteristics of ES are significantly different from COS and ES might have an allergy-related pathogenesis. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E800-E806, 2021.

Allergy-Related Sialodochitis: A Preliminary Cohort Study.

OBJECTIVES/HYPOTHESIS: To explore the clinically feasible diagnosis criteria and treatment outcomes of allergy-related sialodochitis (ARS). STUDY DESIGN: Prospective Cohort Study. METHODS: Ninety-six consecutive patients were enrolled by the following criteria: 1) recurrent swelling of ≥2 large salivary glands that lasted for ≥3 months; 2) with mucus plug exudations; 3) with atopic diseases; 4) ductal stenosis and/or ectasia. Sixty-four patients with elevation of peripheral blood eosinophil (PBE) and/or serum IgE level comprised group A (highly-suspected ARS group), while the remaining 32 comprised group B (patients without confirmed evidence of ARS). These patients were treated with interventional endoscopy. A chronic obstructive sialadenitis symptom (COSS) questionnaire was used to quantify the treatment outcomes. RESULTS: In group A, Serum IgE was elevated in 84.4% of patients and PBE was elevated in 34.4% of patients. Percentage of submandibular gland involvement was higher in group A than group B (48.4% vs. 18.8%). On sialograms, the snowflake changes of branch ducts were seen in higher percentage of group A compared with group B (59% vs. 35% for parotid glands, 27% vs. 8% for submandibular glands, respectively). Mucus plug smears showed abundant eosinophils in 14 group A patients. Biopsy of five group A patients revealed significant eosinophil infiltration around the main and interlobular ducts. During follow-up, the COSS scores were significantly decreased in both groups, and group B was improved better than group A. CONCLUSION: PBE and serum IgE are important diagnostic indexes of ARS. Mucus plug smear or histopathology verifies the diagnosis. Interventional endoscopy is helpful for ARS cases. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:2030-2035, 2021.

[Evaluation of the in vitro quantitative measurement of II degree furcation involvements in mandibular molars by cone-beam computed tomography].

OBJECTIVE: To evaluate the accuracy of measurement of II degree furcation involvements in molars of dry mandibles by cone-beam computed tomography (CBCT). METHODS: Twenty molars with II degree furcation involvements in dry mandibles were examined directly and measured by CBCT. Eight parameters were selected to describe the exact appearance of each II degree furcation involvements, including vertical defect dimensions, horizontal defect dimensions and furcation entrance dimensions. The results were compared with the corresponding data obtained by probing and periapical radiograph. RESULTS: All furcation involvements could be correctly classified by CBCT. For 5 of 8 parameters, no significant difference was found between the data obtained by CBCT and probing measurements (P>0.05). The distances from furcation entrance to alveolar crest, to bottom of bone pocket, and to the deepest site of horizontal bone defect measured by CBCT were less than those probed directly (P<0.05), but the differences were less than 0.5 mm (0.21, 0.24, 0.35 mm, respectively). The localization of furcation entrance may cause the differences. Two out of 20 furcation involvements could not be detected on periapical radiographs, and only 2 of 8 parameters could be measured on periapical radiographs. CONCLUSION: CBCT could provide precise and detailed 3D images of II degree furcation involvements in vitro.

Treatment strategy of hilar and intraglandular stones in wharton's duct: A 12-year experience.

OBJECTIVES/HYPOTHESIS: To suggest a strategy for transoral removal of hilar and intraparenchymal submandibular stones. STUDY DESIGN: Retrospective case series. METHODS: Retrospective evaluation was performed for 514 consecutive patients with hilar and intraparenchymal submandibular stones treated via endoscopy-assisted surgery from January 2006 to June 2018. Three patients had bilateral stones. The stones were classified as: hilar (type I), posthilar (type II), intraparenchymal (type III), and multiple stones (type IV). RESULTS: The affected glands included 311 with type I, 84 with type II, 65 with type III, and 57 with type IV stones. Stones were successfully removed in 478 glands (92.5%, 478/517). Main treatment techniques included hilum ductotomy in 311 glands, intraparenchymal ductotomy in 68, submandibulotomy in 14, intraductal retrieval in 74, and hilum ductotomy accompanied by intraductal retrieval in 11. At a mean 40-months follow-up of 478 successful cases, clinical outcomes were good in 425, fair in 27, and poor in 26 glands. Postoperative sialograms in 75 stone-free patients were categorized as: type I, normal (n = 6); type II, ectasia or stenosis in the main duct and no persistent contrast on functional films (n = 44); type III, ectasia or stenosis in the main duct and mild contrast retention (n = 15); and type IV, poor shape of the main duct and evident contrast retention (n = 10). Postoperative sialometry of 32 patients revealed no significant differences of the gland function between the two sides. CONCLUSIONS: Appropriate use of various endoscopy-assisted approaches helps preserve the gland and facilitates recovery of gland function in patients with different depths of hilo-parenchymal submandibular stones. LEVEL OF EVIDENCE: 4 Laryngoscope, 130:2360-2365, 2020.

Morphologic Analysis of Maxillary Sinus Floor and its Correlation to Molar Roots using Cone Beam Computed Tomography.

OBJECTIVE: To analyse the anterior extension of the maxillary sinus, distribution of the sinus septa and vertical relationship between the maxillary sinus and molar roots using cone beam computed tomography (CBCT). METHODS: Imaging data of 970 consecutive patients who underwent CBCT scans were retrospectively collected. The anterior border, septa distribution of the maxillary sinus and relationship between the maxillary sinus and molar roots were analysed. The root-sinus relationship was divided into three types; the roots protruding into the sinus or touching the floor without a bony barrier was defined as Type I root-sinus relationship. RESULTS: Overall, 15.5% of the maxillary sinuses extended beyond the incisor region and 68.9% extended beyond the canine region. A bony septum of ≥ 2 mm was detected in 16.9% (328/1940) of the maxillary sinuses from 26.0% (252/970) of the patients. Among the 355 septa in the 328 sinuses with septa, 108 (30.4%) were located at the first and second premolar region, 180 (50.7%) at the first and second molar region and 67 (18.9%) posterior to the second molar. Among the first molars, a Type I root-sinus relationship was detected in 61.0% of palatine roots, 55.4% of distobuccal (DB) roots, and 52.7% of mesiobuccal (MB) roots. Moreover, among three-rooted second molars, a Type I relationship was detected in 62.0%, 58.2% and 45.8% of MB, DB and palatine roots, respectively. CONCLUSION: The maxillary sinus can extend beyond the incisor region; approximately 1/6 of sinuses have bony septa; and 1/2 of molar roots protrude into the maxillary sinus or touch the sinus floor without a bony barrier.

Three-dimensional radiographic features of ameloblastoma and cystic lesions in the maxilla.

OBJECTIVES: To characterize the radiographic features of maxillary ameloblastoma (AM), odontogenic keratocyst (OKC) and dentigerous cyst (DC) comparatively by using spiral CT and cone beam CT (CBCT). METHODS: Clinical records, histopathological reports, and nonenhanced spiral CT or CBCT images of 191 consecutive patients with primary maxillary AMs, OKCs, or DCs were retrospectively acquired, and radiographic features were analyzed. RESULTS: The study included 118 males and 73 females (age: 5-84 years). 72.0% of AMs and 84.3% of OKCs originated from the posterior maxilla, while 69.6% of DCs occurred in the anterior maxilla. Among 25 AMs, 44.0% were of desmoplastic type, with honey-combed appearance. 84.0% of AMs were circular or oval in shape, 84.0% expanded buccally, and 36.0% invade the nasal floor. Among 89 OKCs of 88 patients, 61.8% were circular or oval, 58.4% expanded buccally, 49.4% were dentigerous, 41.6% nearly filled the maxillary sinus, and 13.5% invaded the nasal floor. 93.7% (74/79) of DCs enveloped a single tooth, and the tooth-cyst relationship was centripetal in 35, eccentric in 30, and circumferential in 9. Moreover, 98.2% (55/56) of the cysts enveloping a supernumerary tooth were DCs, while 80.9% (38/47) of the cysts enveloping the third molar were OKCs. CONCLUSIONS: Maxillary AMs tend to grow with buccal expansion and invade the nasal floor, and DAs with honey-combed lobularity are common. Maxillary OKCs have variant shapes and tend to invaginate the maxillary sinus. The tooth-cyst relationship of dentigerous OKCs and DCs can be centripetal, eccentric, or circumferential.

Prevalence and Morphology of Mandibular Incisive Canal: Comparison among Healthy, Periodontitis and Edentulous Mandibles in a Population of the Beijing Area Using Cone-beam Computed Tomography.

OBJECTIVE: To evaluate and quantify the prevalence and morphology of the mandibular incisive canal (MIC) comparatively among healthy, periodontitis and edentulous mandibles using cone-beam computed tomography (CBCT). METHODS: CBCT images of 1,070 hemimandibles from 535 consecutive patients, including 448 with healthy dentition, 42 with severe periodontitis mandibles and 45 with edentulous mandibles, were retrospectively analysed. MICs were identified, and linear measurements were performed. Statistical analyses were conducted to investigate differences in the prevalence and morphology of MICs relative to gender, laterality, age group and dental status. RESULTS: The MIC was observed in 92.8% of 1,070 hemimandibles. No significant differences of MIC prevalence were found between left and right sides, or between healthy and periodontitis mandibles. However, males had a higher prevalence of MIC than females, and patients with dentate mandibles had a higher prevalence of MIC than those with edentulous mandibles. For dentate mandibles, MICs started most commonly below the first premolar (51.9%) and ended around the canine (58.5%). The mean diameter of MIC was 2.5 ± 0.5 mm at origin, and 20.6% of MICs began with a diameter of ≥ 3 mm. The mean length of MIC was 13.4 ± 3.3 mm. The mean distances from the MIC to the labial cortex, lingual cortex, alveolar ridge and inferior border of mandible were 3.7 ± 0.9, 5.1 ± 1.6, 19.5 ± 3.8 and 8.9 ± 1.7 mm, respectively. Moreover, significant differences of measurements were found relative to gender, age group, and dental status. CONCLUSION: Due to the large variations in size and course of MICs, special caution should be exercised in any individual surgery affecting the anterior mandible.

Bifid variations of the mandibular canal: cone beam computed tomography evaluation of 1000 Northern Chinese patients.

OBJECTIVES: The aim of this study was to evaluate and quantify variations of bifid mandibular canals (BMCs) in a population of Northern China by using cone beam computed tomography (CBCT). STUDY DESIGN: CBCT images of 1000 consecutive patients were analyzed by using the NewTom proprietary software. BMCs were identified and classified on the basis of the Naitoh classification. Linear and angular measurements of BMCs were performed. Statistical analyses were conducted by using χ2 and Wilcoxon tests. RESULTS: BMCs were observed in 13.2% of 1000 patients and 8.4% of 2000 sides. The prevalence of BMCs was significantly lower in patients in the first 2 decades and in cases with a class II molar relationship. The retromolar canal (68.4%) was the most common type of BMC observed. No buccolingual canals were identified; however, 2 special canals were detected. A classification system of 3 subtypes of retromolar canals was suggested. On average, the beginning site of the branches from the opening of the main canal was at a distance of 8.1 mm. The mean diameter and length of BMCs were 2.1 mm and 12.6 mm, respectively. CONCLUSIONS: This study underlined the prevalence and characteristics of BMCs in a population of Northern China. Preoperative identification of BMCs with CBCT may help prevent postoperative complications.

[Investigation of temporomandibular joint space of healthy adults by using cone beam computed tomography].

OBJECTIVE: To investigate the condyle position in the fossa and obtain the reference ranges of Temporomandibular joint (TMJ) space of 50 healthy adults (100 joints) by using cone beam computed tomography (CBCT). METHODS: Fifty healthy adults (100 joints) were selected and undergone CBCT examination in the intercuspal position. Five different methods of joint space measurement were used based on the joint sagittal middle layer of CBCT images and the results were analysed statistically. RESULTS: The reference ranges of TMJ space of CBCT images by using five measurement methods were obtained. The results of the linear measurement methods demonstrated that there were no significant differences between anterior and posterior spaces (Z0.05),no significant differences between the two side joint spaces including anterior, posterior and superior spaces (t0.05 ),and also no significant differences in ln (P/A) values between two side joints (t0.05). CONCLUSION: All the results of the five measurement methods showed that the condyle was located in the center of the fossa with a variation in the healthy adults in intercuspal position.The CBCT image of the sagittal middle layer of the joint could show the joint space accurately and has an important value in the research related to the changes of TMJ space.