The effect of citric acid on retained plaque and calculus. A short communication

Five extracted human teeth with clinically demonstrable calculus were used. One proximal surface of each tooth was partly scaled, leaving a small amount of calculus. The crown was then cut off at the cementoenamel junction and the scaled proximal surface was divided vertically into two segments using a thin separating disk. One segment was treated by rubbing cotton pellets soaked in citric acid (pH1) over the surface for three minutes and then immersing the segment in saline to stop the reaction. The other (control) segment was treated by rubbing cotton pellets soaked in saline over the surface for three minutes. When viewed under a scanning electron microscope, the control sections displayed scaling striations, considerable surface debris, and large numbers of bacteria at the borders of the residual calculus. Citric acid-treated specimens displayed little debris on cementum or residual calculus and virtually no bacteria at the junction between calculus and cementum. The surface morphology of the citric acid-treated calculus varied from layered-like to honeycomb.     

Effect of a desensitizing agent containing glutaraldehyde and HEMA on bond strength to Er:YAG laser-irradiated dentine

OBJECTIVES: The aim of this study was to investigate whether a desensitizing agent (GLUMA Desensitizer) containing glutaraldehyde and HEMA improved the bond strength and bonding durability of a self-etching primer adhesive to Er:YAG-irradiated dentine. METHOD: Dentine of 120 human molars was exposed by wet grinding on SiC paper for bond strength testing. Thirty specimens each were allocated to the following treatment groups: (1) control; (2) Er:YAG laser irradiation; (3) Er:YAG laser irradiation followed by application of GLUMA Desensitizer; (4) Er:YAG laser irradiation followed by application of GLUMA Desensitizer and 10s rinsing with water. Composite cylinders were bonded to the dentine surfaces with a self-etching priming adhesive system. Tensile bond strengths (TBS) of 10 specimens of each treatment group were measured after 24-h water storage, 6 months water storage and 12 months water storage, respectively, and the failure modes were analyzed. TBS data were statistically treated by two-way ANOVA and Fisher's PLSD test at a significance level of p<0.05. RESULTS: TBSs for the GLUMA-non rinse and GLUMA-rinse groups were significantly higher than for the laser group at 24 h and 12 months. Specimens from the Er:YAG-irradiated dentine group had significantly lower bond strengths than the control group at each storage time. All control specimens showed cohesive fractures in resin close to the bonding interface whereas the Er:YAG laser-irradiated groups showed both dentine cohesive, resin cohesive and dentine-resin mixed failures. CONCLUSION: Application of GLUMA Desensitizer to Er:YAG-irradiated dentine increases the bond strength and durability of the self-etching priming adhesive used.     

Effects of TGF-beta on hyaluronan anabolism in fibroblasts derived from the synovial membrane of the rabbit temporomandibular joint

Hyaluronan (HA) synthesis in the synovial membrane is affected by various chemical mediators. It is hypothesized that transforming growth factor-beta 1 (TGF-beta 1) would be a mediator to modulate HA synthesis in cultured synovial membrane fibroblasts of the temporomandibular joint (TMJ). Fibroblasts were extracted from the TMJ synovial membrane of four-week-old Japanese white rabbits. The amount of HA and expression levels of HA synthase (HAS) mRNAs induced by TGF-beta 1 treatment were analyzed by means of high-performance liquid chromatography and real-time polymerase chain-reaction, respectively. Both medium and large amounts of HA were enhanced by the stimulation of TGF-beta 1. HAS2 mRNA expression was enhanced 13-fold after six-hour stimulation with TGF-beta 1 (10 ng/mL), whereas HAS3 mRNA expression was not changed significantly. These results suggest that TGF-beta 1 enhances the expression of HAS2 mRNA in the TMJ synovial membrane fibroblasts and may contribute to the production of high-molecular-weight HA in the joint fluid.     

Dynamic magnetic resonance sialography as a new diagnostic technique for patients with Sjögren's syndrome

Objective: To evaluate the clinical utility of dynamic magnetic resonance (MR) sialographic images as a diagnostic tool for patients with Sjögren's syndrome. Methods: The morphological findings and various kinds of functional parameters in volunteers on dynamic MR sialographic images were compared with those in five patients with definite Sjögren's syndrome. Results: On the MR sialographs of all five patients with Sjögren's syndrome, the so‐called ‘apple‐tree appearance’ was seen. The difference in two functional parameters using the dynamic MR sialographic data was elucidated between the two groups. The maximum area of the detectable ducts in the group of patients was significantly smaller (P < 0.001) than that in the group of volunteers. The ratio of change in the detectable ducts in the group of patients was significantly lower (P = 0.011) than that in the group of volunteers. Conclusions: Our study suggests that dynamic MR sialographic data in addition to MR sialographic images might be useful for the diagnosis of Sjögren's syndrome.     

Effects of ultrasound on the proliferation and differentiation of cementoblast lineage cells

BACKGROUND: The purpose of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) stimulation on the proliferation and differentiation of cementoblast lineage cells. METHODS: An immortalized human periodontal ligament cell line (HPL) showing immature cementoblastic differentiation was used. Cultured HPL cells were subjected to LIPUS exposure (frequency = 1 MHz; pulsed 1:4; intensity = 30 mW/cm(2)) or sham exposure for 15 minutes per day. Expression levels of alkaline phosphatase (ALP), type I collagen (Col-I), runt-related gene 2 (Runx2), bone sialoprotein (BSP), osteocalcin (OCN), and osteopontin (OPN) mRNA were analyzed with real-time polymerase chain reaction analysis. Furthermore, ALP activity, collagen synthesis, and protein level of Runx2 were examined after 6 days of LIPUS exposure. RESULTS: mRNA and protein levels of ALP, Col-I, and Runx2 were significantly increased by LIPUS exposure compared to controls, whereas BSP, OCN, and OPN mRNA expression could not be detected in HPL cells, irrespective of LIPUS exposure. CONCLUSION: LIPUS enhanced ALP activity, collagen synthesis, and Runx2 expression of HPL cells, which provides important insight into the promotion of early cementoblastic differentiation of immature cementoblasts.     

Relationship between smoking status and periodontal conditions: findings from national databases in Japan

BACKGROUND AND OBJECTIVE: The association between cigarette smoking and periodontitis was examined employing two nationally representative samples of adults in Japan. MATERIAL AND METHODS: Data were derived from the Survey of Dental Diseases (SDD) and the National Nutrition Survey (NNS) in 1999. In the SDD, periodontal conditions were evaluated by calibrated dentists utilizing the Community Periodontal Index (CPI), whereas in the NNS, participants were interviewed on the basis of smoking status by enumerators. Among 6805 records electronically linked via a household identification code, 4828 records of individuals aged 20 yr or older were analyzed. RESULTS: The prevalence of periodontal disease varied significantly by smoking status (p < 0.0001): 39.3%, 49.5% and 47.3% (CPI > or = 3), and 7.9%, 11.7% and 12.4% (a more severe form of periodontitis, CPI = 4), for nonsmokers, former smokers and current smokers, respectively. In adults aged > or = 40 yr (n = 3493), logistic regression models revealed greater probabilities (approximately 1.4 times higher) of periodontitis [CPI > or = 3, odds ratio = 1.38 (1.12-1.71), p = 0.0024] and a more severe form of periodontitis [odds ratio = 1.40 (1.04-1.89), p = 0.0288] in current smokers compared with nonsmokers, following adjustment for possible confounding factors. CONCLUSION: Based on the findings of this study and other numerous reports, cigarette smoking leads to deterioration of periodontal conditions in Japanese adults.