OBJECTIVETo evaluate the reliability and superiority of micro-CT in marginal leakage assessment of Class V restorations.

METHODSClass V preparations with gingival margins in dentin and occlusal in enamel were made in sixteen extracted non-carious human molars and restored with dental bonding agents and composite resin. All teeth were then immersed in 50% ammonia-silver nitrate solution for 12 hours, followed by developing solution for 8 hours. Each restoration was scanned by a micro-CT and silver leakage was measured and three-dimensional image of the silver leakage alone cavity wall were reconstructed. Afterward, all restorations were sectioned and examined for leakage depth using a microscope. The silver leakage depth of each restoration obtained by micro-CT and microscope were compared for equivalency.

RESULTSThe silver leakage depths in gingival wall obtained with micro-CT (0.78 mm) and microscope (0.74 mm) showed no significant difference (P > 0.05), while the judgment of leakage depths in occlusal wall in micro-CT image (0.40 mm) was affected by adjacent enamel structure, giving less leakage depths compared to microscope (0.72 mm)(P < 0.01). The three-dimensional shapes of the microleakages displayed clearly by micro-CT alone wall of Class V restorations were multiform and some leakages showed channels on their way to spreading.

CONCLUSIONSMicro-CT can detect precisely the silver leakage in the dentin wall of a restoration and display its three-dimensional shape fully. Enamel structure affects the detection of the silver leakage next to it.

Dental Cavity Preparation ; Dental Enamel ; diagnostic imaging ; pathology ; Dental Leakage ; diagnostic imaging ; pathology ; Dental Restoration, Permanent ; methods ; Humans ; Imaging, Three-Dimensional ; Microscopy ; Molar, Third ; diagnostic imaging ; pathology ; X-Ray Microtomography ; methods

OBJECTIVE: To explore the value of estimating chronologic age based on the grades of mandibular third molar development. To evaluate whether mandibular third molar could be used as an indicator for estimating the age under or over 18 years. METHODS: The mineralization status of mandibular third molar of 1 845 individuals aged 10 - 30 was graded and marked based on Demirjian's classification of grades reformed by Orhan. Gender difference was examined by t-test. A cubic regression model was established to analyze the correlation between third molar and chronologic age. Each grade of age cumulative distribution diagram and ROC curve was respectively performed to evaluate the relationship between third molar and the age of 18. Using Bayes discriminant analysis, an equation was established for estimating the age of 18. RESULTS: The inner-rater reliability was 0.903. Statistical analysis showed a moderate correlation between age and grade. Significant differences of both genders were found only in grade D and H (P < 0.05). Males at the grades from 1 to D and females at the grades from 1 to C were under 18 years old, and both males and females at grade H were over 18 years old. The area under the ROC curve was 0.797 (P < 0.05). CONCLUSION Third molar development shows a high correlation with age, and combined with other indicators, it can be used to estimate the age of 18.
Age Determination by Teeth/methods* ; Asian People ; Bayes Theorem ; China ; Female ; Forensic Dentistry ; Humans ; Male ; Molar, Third/diagnostic imaging* ; Radiography, Panoramic ; Reproducibility of Results ; Sex Characteristics

We present a case of a patient with rare anatomy of a maxillary second molar with three mesiobuccal root canals and a maxillary third molar with four separate roots, identified using multi-slice computed topography (CT) and three-dimensional reconstruction techniques. The described case enriched/might enrich our knowledge about possible anatomical aberrations of maxillary molars. In addition, we demonstrate the role of multi-slice CT as an objective tool for confirmatory diagnosis and successful endodontic management.
Adult ; Asian Continental Ancestry Group ; China ; Dental Pulp Cavity ; anatomy & histology ; diagnostic imaging ; Female ; Humans ; Imaging, Three-Dimensional ; Maxilla ; Molar ; anatomy & histology ; diagnostic imaging ; Molar, Third ; anatomy & histology ; diagnostic imaging ; Root Canal Therapy ; Tomography, X-Ray Computed ; methods ; Tooth Root ; anatomy & histology ; diagnostic imaging

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months.
Adult ; Cone-Beam Computed Tomography ; methods ; Follow-Up Studies ; Fused Teeth ; diagnostic imaging ; Humans ; Image Processing, Computer-Assisted ; methods ; Imaging, Three-Dimensional ; methods ; Male ; Maxilla ; Molar ; abnormalities ; Molar, Third ; abnormalities ; Pulpitis ; diagnostic imaging ; Root Canal Therapy ; Tooth Root ; abnormalities ; Tooth, Supernumerary ; diagnostic imaging ; Tooth, Unerupted ; diagnostic imaging

This paper reported a case of fusion between an impacted third molar and a supernumerary tooth, in which a surgical intervention was carried out, with the objective of removing the dental elements. The panoramic radiography was complemented by the Donovan's radiographic technique; but because of the proximity of the dental element to the mandibular ramus, it was not possible to have a final fusion diagnosis. Hence, the Cone-Beam Computed Tomography-which provides precise three-dimensional information-was used to determinate the fusion diagnosis and also to help in the surgical planning. In this case report we observed that the periapical, occlusal and panoramic were not able to show details which could only be examined through the cone-beam computed tomography.
Adult ; Cone-Beam Computed Tomography ; methods ; Diagnosis, Differential ; Female ; Follow-Up Studies ; Fused Teeth ; diagnostic imaging ; Humans ; Imaging, Three-Dimensional ; methods ; Molar, Third ; abnormalities ; diagnostic imaging ; Patient Care Planning ; Radiography, Bitewing ; Radiography, Panoramic ; Tooth Root ; abnormalities ; diagnostic imaging ; Tooth, Impacted ; diagnostic imaging ; Tooth, Supernumerary ; diagnostic imaging

OBJECTIVETo investigate the development of third molar embryo and establish the normal value of posterior arch length of adolescence in Chengdu.

METHODSThe samples consisted of 40 males and 41 females with Class 1 dentitions, normal second molar occlusion, no history of orthodontic treatment, and good facial balance. Cephalometry and statistic analysis were conducted for all the subject.

RESULTSThe normal value of posterior arch length of maxilla in male was(16.52 +/- 2.35) mm and in female was(16.42 +/- 2.55) mm. The normal length of mandible was(13.00 +/- 2.44) mm in male and(12.43 +/- 2.18) mm in female. But statistic analysis showed no gender difference. Most of the third molar embryo had been formed and their tooth crowns had been calcified, the occurrence ratio was 84.0% in maxilla and 85.2% in mandible. Most of them located in the middle and inclined mesially.

CONCLUSIONThe data obtained in this study will be valuable for our clinical practice and be helpful for the study concerning dento-facial growth and development.

Adolescent ; Alveolar Process ; anatomy & histology ; diagnostic imaging ; Cephalometry ; Child ; Dental Arch ; anatomy & histology ; diagnostic imaging ; Dental Occlusion ; Dentition ; Female ; Humans ; Male ; Mandible ; anatomy & histology ; diagnostic imaging ; Maxilla ; anatomy & histology ; diagnostic imaging ; Molar, Third ; anatomy & histology ; diagnostic imaging ; Radiography ; Reference Values ; Tooth Migration