Education of dentists in China

China is geographically located in the east of Asia and its population exceeds 1.3 billion. An understanding of dental education in China is thus of interest. However, as there is little published information on this topic, this paper provides information about China regarding its dental history, dental school system including curriculum and dental licensure. High school graduates take a nationwide entrance examination to apply for dental school, of which there are more than 50 in China. A five year dental education leads to the BDS degree. Dental school graduates must then pass the nationwide licensure examination to practise dentistry. Currently, there are not adequate numbers of dentists to provide the necessary oral health care for people living outside metropolitan areas.     

A demographic analysis of vertical root fractures

Teeth with vertical root fractures (VRFs) have complete or incomplete fractures that extends through the enamel, dentin and pulp, down the long axis of the tooth. Several different variables were investigated and statistically evaluated as to their correlation with the presence of VRFs. Specifically analyzed were gender, tooth location, age, radiographic and clinical findings, bruxism, and pulpal status. The data were collected from three different endodontists, from three different geographic locations, comprising a total of 227 teeth. Although VRFs may occur in conjunction with any of the parameters investigated, only certain factors were found to occur in a significant number of cases. The results indicate that VRFs are statistically more prevalent in mandibular molars and maxillary premolars. They are associated with periradicular bone loss, pain to percussion, extensive restorations, and seem to occur more often in females and older patients. However, VRFs are not necessarily related to periapical bone loss, a widening of the periodontal ligament space, associated periodontal pockets, a sinus tract, particular pulpal status, or bruxism.     

Isolation and characterization of Lactobacillus species inhibiting the formation of Streptococcus mutans biofilm

Oral bacterium S11 was isolated from the saliva of young children without dental caries and with little or no visible supragingival plaque. The S11 strain showed 99.5% similarity with Lactobacillus fermentum, and was identified on the basis of biochemical characteristics and a 16S rDNA sequence. S11 strain and its culture supernatant significantly inhibited the formation of the insoluble glucan produced by Streptococcus mutans Ingbritt. S11 did not affect the multiplication of S. mutans Ingbritt, but the adherence of S. mutans Ingbritt onto cuvette walls was inhibited completely.     

Effects of dentin bonding agents on bonding durability of a flowable composite to dentin

The present study evaluated the bonding durability of a flowable composite on bovine dentin using dentin bonding agents with different numbers of application steps: Scotchbond Multipurpose (three steps), Prime & Bond NT and One-Step (two steps), AQ Bond and Prompt L-Pop (one step). Shear bond strength tests were performed, and resin-dentin interface and fracture mode were observed. There were no significant differences in bond strength among the specimens within 37 degrees C storage group (p > 0.05) and post-thermocycling group, except between Prompt L-Pop and Scotchbond Multipurpose (p < 0.05) in the post-thermocycling group. Further, Scotchbond Multipurpose and One-Step showed significantly lower bond strengths after thermocycling (p < 0.05). It was thus shown that the use of simplified bonding agents did not necessarily improve the bonding strength of flowable composites.     

Zygomaticomandibularis muscle

The aim of this study was to elucidate the precise anatomy of the zygomaticomandibularis muscle through cadaveric dissection and magnetic resonance imaging (MRI). Five fresh human cadavers and 10 fixed cadavers were dissected. Nine preserved human cadavers were used for the MRI study. Four volunteers took MRIs of their head as well. Zygomaticomandibularis muscle was found in all the cadaveric specimens. It is a fan shaped muscle. The length of the muscle is 25.1 +/- 4.6 mm, and the width at the zygomatic arch is 16.6 +/- 4.2 mm. The thickness is approximately 4.8 +/- 1.9 mm. It originates from the deep layer of the deep temporal fascia approximately 1 cm above the zygomatic arch and is inserted into the superior border and outer surface of the mandible between the coronoid process and mandibular notch. The deepest layer of the masseter muscle covers the lateral surface of zygomaticomandibularis. We believe that this muscle functions as coordinator of the temporalis and masseter in mammals with strong masticatory power but is a degraded or rudimentary muscle in humans.     

Nasal reconstruction with double-layer tensor fascia lata-wrapped diced rib cartilage in a patient with severe dorsal collapse

For patients with large dorsal defects due to posttraumatic deformities, rib cartilage or calvarial bone is used for reconstruction. Problems such as graft contour, distortion, limited amounts, and donor morbidity continue to exist for cartilage and bone grafts. To overcome the limitations of such grafts, many authors have used diced cartilage wrapped with fascia. However, diced cartilage wrapped with fascia is not suitable for structural support in cases of dorsal nasal collapse. We describe a technique using a dorsal structural graft for a 28-year-old man who had severe dorsal nasal collapse after a traffic collision. For enhancement of strength, we harvested a thick segment of the tensor fascia lata and applied 2 layers. A large amount of rib cartilage was inserted between the thick fascia layers. The tensor fascia lata wrapped with diced cartilage graft for dorsal augmentation is fraught with structural graft, similar to bone or cartilage grafts. This semirigid technique may be another option for dorsal structural support of severe nose deformities.     

Eight-week histological analysis on the effect of chitosan on surgically created one-wall intrabony defects in beagle dogs

OBJECTIVE: To evaluate the periodontal tissue regenerative effects of a chitosan/collagen sponge applied to preclinical one-wall intrabony defects surgically created in beagle dogs. MATERIAL AND METHODS: 4 x 4 mm one-wall intrabony defects were surgically created in the bilateral maxillary first and third, and the mandibular second and fourth premolars. The surgical control group received a flap operation only, while the buffer control group was treated afterwards with a phosphate-buffered saline/collagen sponge (CS) and the chitosan group was treated with a chitosan/cs. The subjects were killed 8 weeks after the operation, and a comparative histological examination was performed. RESULTS: The amount of junctional epithelium migration was 2.30+/-1.24 mm in the surgical control group, 1.49+/-1.25 mm in the buffer control group, and 0.26+/-0.59 mm in the chitosan group. A significant difference was exhibited only between the surgical control and the chitosan group (p<0.05). The amount of connective tissue adhesion was 0.68+/-0.60, 1.07+/-0.91, and 0.41+/-0.42 mm in the surgical control, buffer control, and the chitosan group, respectively. The amount of cementum regeneration was 1.42+/-0.49, 1.60+/-0.41, and 3.46+/-0.78 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was seen between the chitosan group and the rest (p<0.01). The amount of alveolar bone regeneration was 1.00+/-0.77, 1.52+/-0.37, and 2.43+/-0.44 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was observed between the chitosan group and the rest (p<0.05). CONCLUSION: The results demonstrate the beneficial effect of the chitosan/cs on the one-wall intrabony defects of beagle dogs. The inhibited apical migration of epithelium and the increase in the amount of new bone and new cementum suggest the potency of chitosan in inducing periodontal tissue regeneration.     

Specific orofacial problems experienced by musicians

BACKGROUND: Patients who play musical instruments (especially wind and stringed instruments) and vocalists are prone to particular types of orofacial problems. Some problems are caused by playing and some are the result of dental treatment. This paper proposes to give an insight into these problems and practical guidance to general practice dentists. METHOD: Information in this paper is gathered from studies published in dental, music and occupational health journals, and from discussions with career musicians and music teachers. RESULTS: Orthodontic problems, soft tissue trauma, focal dystonia, denture retention, herpes labialis, dry mouth and temporomandibular joint (TMJ) disorders were identified as orofacial problems of career musicians. Options available for prevention and palliative treatment as well as instrument selection are suggested to overcome these problems. Conclusions: Career musicians express reluctance to attend dentists who are not sensitive to their specific needs. General practitioner dentists who understand how the instruments impact on the orofacial structures and are aware of potential problems faced by musicians are able to offer preventive advice and supportive treatment to these patients, especially those in the early stages of their career.     

Pharmacokinetic profile of a locally administered doxycycline gel in crevicular fluid,blood, and saliva

BACKGROUND: With the help of so-called controlled release delivery systems, the half-life period of locally administered antibiotics in gingival crevicular fluid (GCF) can be extended significantly. The aim of this study was to characterize the delivery profile of a new one-component 14% doxycycline free amine gel for local application. Pharmacokinetics of doxycycline (DOXY) were analyzed in GCF, saliva, and serum. METHODS: Twenty patients with persisting or recurring pockets (probing depths > or = 5 mm and bleeding on probing) after mechanical treatment (surgical or non-surgical) took part in the study. In each patient 1 periodontal defect was treated with DOXY gel. Samples of GCF, saliva, and serum were obtained before application of DOXY gel; 15 minutes after application; at 2 and 5 hours; and at 1, 2, 3, 4, 7, 9, and 11 days after application. Separation and quantitative measurement of DOXY was performed with high performance liquid chromatography and UV detection at lambda = 260 nm. RESULTS: Coefficients of variation were lower than 2% (intraassay) and 4% (interassay), respectively. For concentrations between 50 to 1000 microg/ml, we found a linear relationship between expected and measured DOXY values (linear coefficient of correlation: r = 0.998). Within the first 5 hours after application, concentration of DOXY in GCF (maximum after 15 minutes 19.97 +/- 5.85 mg/ml) and saliva (maximum after 15 minutes 17.83 +/- 2.84 mg/ml) was similar. Then concentration fell to a lower level (28.90 +/- 19.44 microg/ml) compared to GCF (577.41 +/- 127.34 microg/ml) after 3 days. Up to 10 days after application, the concentration of DOXY in GCF was 34.24 microg/ml. With the exception of 1 patient, all serum samples were DOXY-negative. CONCLUSIONS: 1) After subgingival application of biodegradable 14% doxycycline gel, mean doxycycline levels in GCF that exceeded 16 microg/ml could be maintained for at least 12 days. Thus, the antimicrobial agent may be classified as a controlled release device. 2) The antibiotic effect was limited mainly to the subgingival sites of application of the doxycycline gel. 3) The doxycycline gel possesses the pharmacokinetic and clinical properties to deliver efficacious levels of antibiotics to the periodontal pocket and to maintain these levels for at least 1 week without the need of further drug retention by a periodontal dressing.     

Use of separate single-tooth implant restorations to replace two or more consecutive posterior teeth: a prospective cohort study for up to 1 year

PURPOSE

The aim of this study was to evaluate the periodontal and prosthodontic complications of multiple freestanding implants in the posterior jaws for up to 1 year of function.

MATERIALS AND METHODS

Eight patients received 20 implants posterior to canines. Two or more implants were consecutively inserted to each patient. Single crowns were delivered onto the implants. Marginal bone loss, implant mobility, probing depth, and screw loosening were examined to evaluate the clinical success of such restorations for maximum 1 year of functional loading.

RESULTS

All the implants performed well during the observation period. Neither periodontal nor prosthodontic complications were found except a slight porcelain chipping. While the marginal bone level was on average 0.09 mm lower around the implant after 6 months of loading, it was 0.15 mm higher after 1 year.

CONCLUSION

Within the limits of this investigation, separate single-tooth implant restorations to replace consecutive missing teeth may clinically function well in the posterior jaw.