Chinese Journal of Dental Research, 02/2009

Keratoconjunctivitis sicca, characterized by reduction or lack of tears with the resulting consequences, is a relatively common disease. The current therapeutic options are largely symptomatic and insufficient in severe cases. During the last 10 years, 141 cases (150 eyes) of severe keratoconjunctivitis sicca have been treated by autologous submandibular gland transfer. It has been shown that autologous submandibular gland transfer is a lasting and effective solution for the severe cases. However, there are two main problems with this method that need to be resolved. One is that a lower flow rate leads to the obstruction of Wharton's duct in the early stage after transfer. The other is that half of the patients suffer from epiphora in the long term. In order to resolve the two problems, both clinical and basic research were performed to modify surgical procedures and to understand the mechanisms underlying the secretion of the transferred submandibular gland. We found that partial submandibular gland transfer could prevent or alleviate epiphora and that α1- and ß-adrenoceptors and vanilloid receptor 1 were involved in the secretion by normal and transferred submandibular glands. The agonists of these receptors could moderate structural injury and improve secretory function in the transferred submandibular gland. Keywords: keratoconjunctivitis sicca, dry eye syndrome, autologous submandibular gland transfer, receptor, surgery

Ameloblastomas are remarkable among odontogenic tumours because of their particular clinical and histological behaviours, including infiltrative potential, high recurrence rate and capacity to metastasise. Knowledge of the mechanism for invasion is essential for selecting the most appropriate therapeutic approach and anticipating a prognosis for each case. In this paper, some up-to-date frontier research on the different molecular biological aspects related to the invasiveness of ameloblastoma is reviewed to elucidate several points that still remain unclear. Keywords: ameloblastoma, invasiveness, molecular mechanism

Objective: To assess the clinical characteristics of oral lichen planus (OLP) in a Chinese cohort. Methods: A total of 539 OLP patients were enrolled in this study. Clinical and histopathological examinations were used for diagnosis. All data were analyzed statistically by t test, chi-square test, and Spearman correlation analysis with SPSS. Results: The mean age of OLP patients was 50.2 years. The ratio of males to females was 1:1.44. Reticular type occurred in 56.40% of the patients, followed by erosive type (24.86%) and erythematous type (18.74%). Patients aged less than 40 years were susceptible to reticular lesions (P = 0.001) whereas patients more than 60 years were susceptible to erosive lesions (P < 0.05). In total, 25.34% of the OLP male patients were smokers, higher than that of the control group (16.76%; P < 0.05). With the increase of duration and quantity of tobacco consumption, the erosion type became less frequent (P = 0.009 and 0.007 respectively). However, no difference in smoking was observed between the women with and without OLP. Conclusion: OLP occurs more commonly in middle-aged women. In patients younger than 40 years, the reticular type occurs more often, whereas erosion type is more common in patients older than 60 years. Erosion was less frequent in the OLP patients who smoked. Keywords: lichen planus, oral disease, mucosa oral lichen planus, smoking

Objective: To evaluate the effects of a remineralisation solution (RS) containing lower fluoride (F), calcium (Ca) and phosphate (P) in comparison with conventional NaF rinse on F and Ca uptake by dental plaque, and on acid resistance and remineralisation of enamel. Methods: Eight subjects participated in this randomised, double-blind and cross-over in vivo study. Subjects wore removable appliances mounted with a pair of enamel blocks and applied the RS rinse and conventional NaF rinse three times per day for 1 week, repectively. The RS rinse, pH 6.5, contained 0.53 mmol/L F of NaF, 15 mmol/L CaCl2, and 9 mmol/L NaH2PO4. The NaF rinse contained 12 mmol/L F. Dental plaque was accumulated for 48 h and collected after fasting overnight after the last use of the rinse. After acid extraction, F and Ca in the plaque were measured by an ion-selective electrode and atomic absorption spectroscopy, respectively. Acid resistance of the enamel was evaluated by microradiography after the enamel blocks were artificially demineralised by acid gel in vitro. The remineralisation of the pre-softened enamel was determined using a microhardness test. Results: Both rinses significantly enhanced F and Ca uptake in whole plaque. RS rinse produced a similar F deposition in plaque to the NaF rinse, although the formulation of RS rinse contained 22.6 times less F than the NaF rinse did. Moreover, RS rinse more effectively enhanced acid resistance and remineralisation of enamel than the NaF rinse did. Conclusion: RS rinse can provide greater cariostatic effects with a lower F dosage than the conventional NaF rinse, with less worry about excessive systemic F intake in children. Keywords: fluoride, dental plaque, mouth rinse, acid resistance, remineralisation

Objective: To evaluate attachment and proliferation of human gingival fibroblasts (HGFs), human periodontal ligament fibroblasts (HPDLFs) and human osteoblasts (HOBs) on diseased root surfaces of human teeth demineralised with EDTA and subsequently treated with freshly prepared platelet-rich plasma (PRP) or platelet-poor plasma (PPP) from human blood. Methods: HGFs, HPDLFs and HOBs were grown from tissue explants. Human whole blood from healthy subjects was collected to prepare PRP and PPP. The root surfaces of periodontitis- affected teeth were scaled, sectioned, and demineralised with EDTA and treated with PPP or PRP or none. The control group was neither demineralised nor treated with PPP or PRP. The cementum surfaces of root slices were cultured with HGFs, HPDLFs or HOBs for 24 or 48 h. Attachment and proliferation of cells were evaluated using cell count, scanning electron microscopy and MTT assay. Results: The root surfaces of the control group demonstrated the least number of attached cells. Demineralisation alone or combined with PRP or PPP increased cell attachment and proliferation. Electron microscopic evaluation further confirmed that both PRP and PPP significantly enhanced cell attachment to the diseased root surfaces. Conclusion: Pretreatment of diseased human root surfaces with EDTA, PRP or PPP enhances the attachment and proliferation of HGFs, HPDLFs and HOBs to the diseased root surface. Keywords: periodontal cells, attachment, platelet-rich plasma, platelet-poor plasma, demineralisation

Objective: To evaluate the effect of irradiation on adenosine triphosphate (ATP) catabolism in skeletal muscles. Methods: Thirty-six inbred female mice were used in the study. The animals were randomly divided into five irradiated groups and one unirradiated group as control. The left hind legs of the mice in irradiated groups were exposed to a single-dose γ-irradiation of 60 Gy. The concentrations of adenosine monophosphate (AMP), adenosine diphosphate (ADP) and ATP in the irradiated gastrocnemius muscles were determined by high-performance liquid chromatography. Results: In the early periods after irradiation, a significant reduction of the three examined substances was observed in the irradiated gastrocnemius muscle compared with the controls (P < 0.05), whereas the concentrations of AMP, ADP, and ATP in the irradiated legs recovered to the normal level 30 days after irradiation. Conclusion: ATP catabolism in skeletal muscle was influenced by radiation in the early stage. This early disorder of ATP catabolism in the irradiated skeletal muscle might be one of the potential factors that initiate the morphological and functional changes of the muscle in late periods after irradiation. Keywords: γ-irradiation, trismus, ATP catabolism, skeletal muscle, HPLC

Objective: To evaluate the protein expression of interleukin-8 (IL-8) in salivary adenoid cystic carcinoma (SACC) and to analyse its correlation with the clinicopathologic characteristics and prognosis. Methods: A total of 43 cases of SACC and eight of normal salivary tissues were examined for the expression of IL-8 using immunohistochemistry, and the relationship of IL-8 expression with patients' clinicopathologic features was analysed. Results: While the positive staining rate of IL-8 expression in SACC was 79.1% (34/43), the normal salivary tissues showed negative staining of IL-8 (0/8). IL-8 expression in SACC was positively related to distant metastasis of SACC (P < 0.05), but not related to the gender, age, tumour location, and pathological types. Conclusion: The overexpression of IL-8 in SACC might be involved in metastasis of SACC. The potential mechanism underlying IL-8 expression related to the prognosis and treatment of SACC needs further research. Keywords: salivary adenoid cystic carcinoma, interleukin-8, metastasis, prognosis

Objective: To assess the interfacial bond strength of total-etch, two self-etch and self-adhesive resin cement luted endodontic glass-fibre posts. Methods: Sixteen recently extracted human teeth were collected for this study. The teeth were randomly and equally allocated to four groups: group 1, Single Bond 2 (3M ESPE, Seefeld, Germany) in combination with RelyX ARC (3M ESPE, Seefeld, Germany); group 2, ED Primer with Panavia F (Kuraray Co., Okayama, Japan); group 3, ParaBond with ParaCem (Coltène/Whaledent, Altstatten, Switzerland); and group 4, RelyX Unicem (3M ESPE, Seefeld, Germany). Fibre posts were cemented in endodontically treated teeth within the groups. One week later, the cemented posts in each group were processed for thin-slice pushout tests after thermal cycling (1000 cycles, 5/55 °C). Results: The interfacial bond strength was not different among the four groups. The bond strength was significantly higher at the coronal third of the root canal than at the middle- apical third for group 4. The rest of the groups did not show regional differences in bond strength. Conclusion: Single Bond/RelyX ARC, Panavia F, ParaCem, and RelyX Unicem demonstrated an equal potential for adhesion of fibre posts to intraradicular dentine. Keywords: adhesion, fibre post, intraradicular dentine, bond strength, push-out test

Objective: To certify that the Vector™ device, a recently introduced piezo-driven ultrasonic device, has an efficacy comparable to conventional instrumentation and leads to a smoother root surface after debridement. Methods: Forty periodontally extracted human teeth were randomly divided into four groups and each group of 10 teeth were treated by one of the following methods in an artificial periodontal pocket for a total of 10 min: hand instrument debridement (HD); conventional ultrasonic system with an 'IS' tip (Satelec); Vector system with abrasive fluid and metal curette (VA); and Vector system with polishing fluid and metal curette (VP). The efficiencies of these four different debridements were assessed using a root calculus figure analysing system with an accuracy of 0.01 mm2. Root smoothness was observed at 7× magnification under a stereomicroscope after root debridement. Results: The calculus removal efficiency of VA did not differ from those of the HD and Satelec groups, while the calculus removal efficiency of the VP group was significantly lower than those of HD and Satelec groups (P < 0.05). The root surfaces in the VA and VP groups were smoother than those in other groups, while the scratches were obvious on the root treated by HD or the Satelec ultrasonic system. Conclusion: This study indicates that the Vector system as a novel means is a promising alternative for initial and maintenance therapy of periodontitis. Keywords: hand instrumentation, root smoothness, ultrasonic instrumentation, artificial periodontal pocket, debridement

Objective: To compare and evaluate the rheological and radiographic properties of AH Plus, Endoflas FS, and Pulpdent root canal sealers using a two-plate system and digital imaging technique. Methods: The rheological and radiological properties of endodontic sealing materials were evaluated according to ANSI/ADA Specification No. 57. The two-plate method was used to evaluate the flow properties and film thickness, and the digital imaging technique was used to evaluate the radiopacity. Results: The results show that all three root canal sealers comply with ANSI/ADA Specification No. 57 requirements for all tests conducted for rheological and radiographic properties. There were statistically significant differences among the three test materials. In all of the tests, the AH Plus root canal sealer showed better rheological and radiographic properties than Endoflas FS and Pulpdent. Conclusion: AH Plus root canal sealer had better rheological and radiographic properties than Endoflas FS and Pulpdent root canal sealers. Keywords: AH Plus sealer, flow, film thickness, radiopacity

A rare case of a malignant peripheral nerve sheath tumour occurring on gingiva in a 9-yearold Chinese girl is presented. Keywords: malignant peripheral nerve sheath tumour, gingiva, children

Multiple supernumerary teeth are rare anomalies of the maxillofacial complex and often occur with some congenital syndromes. This article reports a case of non-syndromic multiple supernumerary teeth with some impacted in both jaws. Keywords: non-syndromic, multiple supernumerary teeth, impacted teeth