Ceramics ; Esthetics, Dental ; Humans

Dentists ; legislation & jurisprudence ; Liability, Legal

OBJECTIVETo develop a method of three-dimensional computer aided design (CAD) of post-and-core restoration.

METHODSTwo plaster casts with extracted natural teeth were used in this study. The extracted teeth were prepared and scanned using tomography method to obtain three-dimensional digitalized models. According to the basic rules of post-and-core design, posts, cores and cavity surfaces of the teeth were designed using the tools for processing point clouds, curves and surfaces on the forward engineering software of Tanglong prosthodontic system. Then three-dimensional figures of the final restorations were corrected according to the configurations of anterior teeth, premolars and molars respectively.

RESULTSComputer aided design of 14 post-and-core restorations were finished, and good fitness between the restoration and the three-dimensional digital models were obtained. Appropriate retention forms and enough spaces for the full crown restorations can be obtained through this method.

CONCLUSIONSThe CAD of three-dimensional figures of the post-and-core restorations can fulfill clinical requirements. Therefore they can be used in computer-aided manufacture (CAM) of post-and-core restorations.

Computer-Aided Design ; Dental Prosthesis Design ; methods ; Humans ; Post and Core Technique

OBJECTIVETo evaluate the genotoxicity of a magnesium alloy coated with beta-tricalcium phosphate (beta-TCP).

METHODSFour groups were designed. In the first group, AZ31B magnesium alloy surface was coated with beta-TCP using chemical bath deposition, and in the second group magnesium alloy was tested. The other two groups were negative control (pure titanium) and positive control groups (0.5 mg/L bleomycin). Single cell gel electrophoresis was adopted to investigate genotoxicity of the alloy samples in different groups, and 60 cells from each group were analysed. Tail moment and tail DNA percentage were used as reliable indicators to show DNA damage in lymphocytes induced by every testing sample. Student-Newman-Keuls (SNK) test was used to compare results from 4 groups.

RESULTSThere were no significant differences in tail moment and tail DNA percentage between magnesium alloy group [(0.52 +/- 0.12), (6.82 +/- 1.81)%] and magnesium alloy coated with beta-TCP group [(0.51 +/- 0.12), (6.89 +/- 1.93)%, P > 0.05]. Tail moment and tail DNA percentage in negative group were (0.47 +/- 0.14) and (6.29 +/- 1.64)%, and tail moment and tail DNA percentage in positive group were (5.17 +/- 1.23) and (22.09 +/- 4.51)%.

CONCLUSIONSNo significant increase was found in DNA damage in lymphocytes induced by magnesium alloy coated with beta-TCP.

Alloys ; Calcium Phosphates ; Coated Materials, Biocompatible ; Electrophoresis, Agar Gel ; Humans ; Magnesium ; Materials Testing

OBJECTIVETo incorporate an antibacterial monomer, methacryloxylethyl cetyl dimethyl ammonium chloride(DMAE-CB), into a dental adhesive, and to evaluate the antibacterial activity against Streptococcus mutans (Sm) of this DMAE-CB-incorporated adhesive after being cured.

METHODSDMAE-CB was incorporated into a dimethacrylates-based dental adhesive as experimental group. The adhesive without DMAE-CB served as a negative control. Thirty-nine specimens were fabricated for each group. The effects of the cured adhesives on the growth and adherence of Sm were evaluated with growth inhibition assay and spectrophotometry respectively. The influence of aging treatment and saliva treatment on the antibacterial efficiency of the modified adhesive was evaluated. Moreover, the bacterial growth of Sm in the eluents of two different adhesives was examined.

RESULTSCompared with negative control, the cured DMAE-CB-incorporated dental adhesive exhibited inhibitory effect on the growth and adherence of Sm. The inhibition rate was 99% and the absorbance value was (0.332 +/- 0.063) for experimental group, significantly lower than that of negative control (0.434 +/- 0.093, P = 0.021). Moreover, after aging treatment the DMAE-CB-incorporated adhesive could still inhibit the growth and adherence of Sm; the inhibition rate was 99%, and the absorbance value of experimental group was (0.372 +/- 0.062), significantly lower than that of negative control (0.455 +/- 0.066, P = 0.022). After saliva treatment the DMAE-CB-incorporated adhesive could still inhibit the growth and adherence of Sm; the inhibition rate was 90%, and the absorbance value of experimental group was (0.299 +/- 0.061), significantly lower than that of negative control (0.370 +/- 0.068, P = 0.045). However, the eluent of DMAE-CB-incorporated adhesive didn't show inhibitory effect on the growth of Sm when compared with negative control, and the antibacterial effect and the doubling time of experimental group [(130.5 +/- 8.4) min] had no statistical difference than negative control [(126.4 +/- 7.0) min, P = 0.298].

CONCLUSIONSThe incorporation of DMAE-CB can render the dental adhesive with antibacterial activity after polymerization via influencing the growth and adherence of Sm.

Ammonium Compounds ; pharmacology ; Dentin-Bonding Agents ; pharmacology ; Streptococcus mutans ; drug effects

OBJECTIVETo report nine cases of descending necrotizing mediastinitis (DNM) and to summarize the management experience.

METHODSBetween December 2005 and December 2008, nine patients (mean age, 55.7 years; age range, 38 to 78 years) with DNM were treated. Eight patients underwent surgical drainage of the involved cervical region and mediastinum (4 with cervical drainage alone; 4 with cervical drainage and right thoracotomy).

RESULTSTwo patients died, one of them refused surgical therapy and the other one died of multiorgan failure related to postoperative septic shock. Seven patients recovered. The mortality rate was 22%.

CONCLUSIONSDelayed diagnosis and inadequate drainage are the main causes of high mortality rate of DNM. Aggressive surgical drainage and debridement of the neck and mediastinum by a multidisciplinary team of surgeons are very important in the treatment of DNM.

Adult ; Aged ; Focal Infection ; complications ; Humans ; Male ; Mediastinitis ; etiology ; Middle Aged

OBJECTIVETo report eight cases of central mucoepidermoid carcinoma of the jaws (CMCJ) and to analyze its clinical and pathological features.

METHODSEight cases of central mucoepidermoid carcinoma were diagnosed between 1989 and 2008. The clinical manifestation, radiological and histopathological changes were analyzed.

RESULTSThe mean age of this group of patients was 43.3 years, with 5 male and 3 female. Seven cases occurred in mandible, mainly in the molar, angle and ramus areas, and one in maxilla. The first complain usually was local swelling, pain or paraesthesia of the jaw and loosening and pain of the tooth. X-ray displayed unilocular or multilocular radiolucent lesion with distinct or ill-distinct border, and the light microscopic findings were similar to the mucoepidermoid carcinoma originated in the salivary gland.

CONCLUSIONSTo diagnose a CMCJ, it's necessary to synthetically analyze the case history, clinical examination, radiological and histopathological features. The treatment is wide local resection. Selective neck dissection and radiochemotherapy may improve curative effect and prognosis.

Adult ; Aged ; Carcinoma, Mucoepidermoid ; pathology ; Female ; Humans ; Jaw Neoplasms ; pathology ; Male ; Middle Aged

OBJECTIVETo investigate the prevalence and influencing factors of dental erosion among college students in Guangzhou and to provide necessary information for the prevention.

METHODSA total of 1704 16-24-year-old students from six colleges or universities were assessed for dental erosion. Data on the social economical status, eating habits, oral hygiene habits, and other related factors were obtained through questionnaire. The influencing factors were analyzed by chi(2)-test and logistic regression analysis.

RESULTSFive hundreds and one of the 1704 subjects suffered from dental erosion (29.4%). The teeth most frequently affected were the upper and lower incisors and first mandibular molar. For tooth surfaces were incisal/occlusal surfaces [66.1% (5491/8311)] and labial/buccal surfaces [31.0% (2574/8311)]. Logistic regression analysis showed that female, those who were not the only child in the family, and students who consumed carbonated drinks more than once per week or drank 500 ml or more of acidic beverages per week were more likely to have dental erosion.

CONCLUSIONSControl of the consuming of acidic beverages is an important measure for the prevention of dental erosion.

Adult ; China ; epidemiology ; Cross-Sectional Studies ; Female ; Humans ; Logistic Models ; Male ; Prevalence ; Tooth Erosion ; epidemiology

OBJECTIVETo investigate the expression of mammary serine proteinase inhibitor(Maspin) in patients with oral squamous cell carcinoma and its relationship with clinicopathological features.

METHODSThe Maspin protein expression was examined in 45 patients with oral squamous cell carcinoma and in non-malignant oral epithelia by immunohistochemical staining. The relationship between the Maspin protein expression and the clinicopathological parameters was statistically analyzed.

RESULTSThe Maspin protein expression in the cancerous tissues of oral squamous cell carcinoma was lower than that in the non-malignant oral epithelia (P = 0.001). Negative correlation was found between the Maspin protein expression in cancerous tissue and the status of lymph node metastasis (P = 0.038). Positive Maspin protein expression indicated negative lymph node metastasis, and negative correlation was also found between the Maspin protein expression and the postoperative metastasis (P = 0.004). Positive correlation was found between the Maspin expression and the patients' survival rate (P = 0.014), patients with positive Maspin protein expression having higher survival rate than those with negative Maspin expression.

CONCLUSIONSMaspin might be useful as a potential prognostic marker for oral squamous cell carcinoma.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; metabolism ; pathology ; Female ; Humans ; Male ; Middle Aged ; Mouth Neoplasms ; metabolism ; pathology ; Serine Proteinase Inhibitors ; metabolism ; Serpins ; metabolism

OBJECTIVETo evaluate (18)F-fluorodeoxyglucose-position-emission tomography-computer tomography imaging ((18)F-FDG-PET-CT) on head and neck squamous cell carcinoma(HNSCCA) and lymph node metastasis.

METHODS(18)F-FDG-PET-CT imaging of 20 patients with HNSCCA was evaluated retrospectively.

RESULTSAll the primary tumors were correctly diagnosed by (18)F-PET-CT imaging and SUV(avg) of the primary tumors was (6.22 +/- 2.20). All the sensitivity, specificity, positive predictive value and the negative predictive value were 100%. In detecting lymph node metastasis, the sensitivity was 51%, specificity 97.7%, false positive rate 2.3%, false negative rate 49%, positive predictive value 82%, and negative predictive value 91.2%.

CONCLUSIONS(18)F-FDG-PET-CT imaging was valuable in detecting HNSCCA and lymph node metastasis. SUV was helpful for differential diagnosis between benign or malignant tumors but it needs further study to determine the cutoff SUV for differentiating lymph node metastasis.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; diagnostic imaging ; pathology ; Female ; Fluorodeoxyglucose F18 ; Head and Neck Neoplasms ; diagnostic imaging ; pathology ; Humans ; Lymphatic Metastasis ; Male ; Middle Aged ; Positron-Emission Tomography ; methods ; Tomography, X-Ray Computed