Chinese Journal of Dental Research, 01/2015

Oral cancer is a fatal disease, which accounts for the fourth highest incidence of malignancy in males and the seventh highest in the general population of Taiwan. About 95% of oral cancer is oral squamous cell carcinoma (OSCC). The relatively high prevalence of OSCC in Taiwan is mainly because a high-risk group of the population exists, made up of 2.5 million people and who exhibit habits of betel nut chewing as well as cigarette smoking. Unfortunately, about 50% of the new OSCC cases found in medical centers presented with TNM stage III or IV cancer lesions leading to a low 5-year survival. Therefore, it is generally accepted that the prevention and screening of OSCC at early stages or premalignant levels in the high-risk group of the population is as equally important as treatment. In this review article, we describe the current status of OSCC in Taiwan regarding epidemiology. Furthermore we research and highlight the importance of various conventional and novel methods in the detection of this disease. Keywords: betel nut, cigarette smoking, detection, OSCC, prevention

Guideline for the Diagnosis and Management of Dentin Hypersensitivity from the Chinese Stomatological Association Expert Committee on Dentin Hypersensitivity.

The most recent Chinese health care reform, scheduled to run until 2020, has been underway for a number of years. Oral health care has not been explicitly mentioned in the context of this reform. However, oral health is an integral part of general health and the under-servicing of the Chinese population in the area of dental care is particularly high. The article describes how this problem could be addressed. Based on present scientific knowledge,specifically on evidence-based strategies and long-term empirical experience from Western industrialised countries, as well as findings from Chinese pilot studies, the author outlines a preventive oral health care system tailored specifically to the conditions prevailing in China. He describes the background and rationale for a clearly structured, preventive system and summarises the scientific cornerstones on which this concept is founded. The single steps of this model, that are adapted specifically to China, are presented so as to facilitate a critical discussion on the pros and cons of the approach. The author concludes that, by implementing preventive oral care, China could gradually reduce the under-servicing of great parts of the population with dental care that largely avoids dental disease and preserves teeth at a price that is affordable to both public health and patients. This approach would minimise the danger of starting a cycle of re-restorations, owing to outdated treatment methods. The proposal would both fit in well with and add to the current blueprint for Chinese health care reform. Keywords: early caries diagnostics, minimal invasive treatment, non invasive caries management, preventive dentistry, risk-oriented prevention

Objectives: To evaluate the effect of Fe2O3 on the optical properties of yttria-stabilised tetragonal zirconia (Y-TZP) dental ceramic when added, and to determine the correct content required to mimic the natural dentin. Methods: Disc-shaped Y-TZP specimens (0.50 ± 0.01 mm in thickness) containing various contents of Fe2O3 were fabricated by cold isostatic pressing and pressureless sintering, and then compared with human dentin slices (n = 40) under different moisture conditions. The visible light transmittance and colour parameters were recorded by a computer-controlled spectrocolourimeter. Sintered density and microstructure were investigated with the Archimedes' method and scanning electron microscopy (SEM), respectively. Results: With the reduction of moisture in dentin slices, the direct transmittance dropped from 1.58% to 0.87%. The direct transmittance of coloured zirconia specimens, ranging from 1.22% to 1.40%, covered the range of dentin. With increasing Fe2O3 content, the L* value of the coloured specimens decreased from 88.95 to 84.18, while b* increased from 3.43 to 12.02. The relative densities of all groups were over 99% of the theoretical value. The SEM indicated that zirconia with various amounts of Fe2O3 retained the compact microcrystalline tetragonal structure. Conclusion: Small amounts of colourant additions affected the colour and the transmittance slightly, but had no influence on the sintered density and microstructure. Y-TZP could be improved by the control of colourant additives of Fe2O3 in order to mimic the natural colour of dentin and to obtain a better aesthetical appearance of restorations, especially when the content was around 0.08 wt%. Keywords: colourant, Fe2O3, optical property, translucency, Y-TZP, zirconia

Objective: To explore the prevalence of NCCL and associated risk indicators in 35- to 44-year-olds and 65- to 74-year-olds from both urban and suburban districts of Guangzhou, Southern China. Methods: A cross-sectional survey was conducted on NCCL with a sample of 768 35- to 44-year-olds and 991 65- to 74-year-olds, and the Tooth wear index was applied to record the tooth wear. Data on socioeconomic status, health behaviour and general health condition were obtained from a structured questionnaire. Results: The prevalence of NCCL was 76.8% and 81.3% in middle-aged and elderly populations, respectively. The results from the analysis of covariance (ANCOVA) demonstrated that for the 35- to 44-year-olds, those who were male, older, living in the suburban district and used toothpicks frequently, they tended to have more teeth with NCCL. Men, who were aged between 65 and 74 years old, who used toothpicks frequently, drank vinegar beverages, ate hard food and had not visited a dentist in a year; tended to have more teeth with NCCL. Conclusion: NCCL was very common amongst middle-aged and elderly populations in South China. Older men who had unhealthy oral habits like using toothpicks, eating hard food and drinking vinegar beverages tended to have more teeth with NCCL. Oral health education would benefit those at risk. Keywords: non-carious cervical lesions, prevalence, risk indicator

Objective: To explore the early dental interventional strategies for adolescent patients and a child patient with cleidocranial dysplasia (CCD). Methods: Surgical exposure using the apically repositioned flap technique combined with orthodontic traction was used in the adolescent patients whose ideal treatment time for initiating treatment was missed. For the child patient whose ideal treatment time for initiating treatment was not missed, the simple surgical exposure method was carried out in order to promote the eruption of the impacted incisors. Results: All the impacted maxillary incisors of the three CCD patients were successfully positioned into a proper alignment either through the two stages of crown exposure and the elastic traction or simple surgical exposure. Conclusion: Crown exposure surgery combined with light force orthodontic traction provides an effective approach to treat the typical dental abnormalities of adolescent CCD patients. Simple surgical exposure was also an effective way for a child CCD patient for whom the most ideal time for initiation of treatment was not missed. Keywords: cleidocranial dysplasia, dental treatment, orthodontic treatment

Objective: To determine the prevalence of hypodontia in the general population and orthodontic population in adolescent Chinese Hans. Methods: Two groups named the general population (6015 subjects) and the orthodontic population (2781 subjects) were investigated, respectively. The former came from the students of three general universities in North China and the latter came from patients coming to the Department of Orthodontics, Peking University School and Hospital of Stomatology for orthodontic consulting during the summer and winter holidays in 2008. The prevalence and average missing number of hypodontic teeth was investigated in the two groups. The distribution of missing teeth was analysed between jaw positions and between genders. Results: The prevalence of tooth agenesis was found to be 5.89% for the general population group and 7.48% for orthodontic subjects. Tooth agenesis was more frequently found in females than in males in both of the two groups and showed a statistically significant difference (P 0.01). Tooth agenesis was found more frequently in the mandible than in the maxilla in the general population but had no difference in the orthodontic population. The prevalence and the number of missing teeth were higher in the orthodontic population than in the general population. Tooth agenesis showed different characteristics in the two populations. The congenital absence of the second mandibular premolars and the maxillary lateral incisors increased in the orthodontic population. Gender difference in hypodontia expressed an opposite effect in the two groups. Although tooth agenesis was more frequently found in females than in males, males missed more teeth than females in the orthodontic population. Conclusion: Tooth agenesis showed different characteristics between the general and orthodontic adolescent Chinese populations. Keywords: hypodontia, prevalence, orthodontics