Technical quality of root canal treatment in Taiwan

AIM: To evaluate the current technical quality of root canal treatment (RCT) in Taiwan. METHODOLOGY: A total of 1085 RCT cases, randomly selected from a large sample and representative of the Taiwanese population from April to September 2000, were evaluated by eight endodontic specialists. The qualitative evaluation of RCT cases was based on two variables: length of the root filling and density of the obturation. A root canal with both adequate filling length (the apical termination of the root filling within 2 mm of the radiographic apex) and complete obturation (no lateral or apical canal lumen visible in the apical one-third of the root canal) was defined as having good-quality endodontic work (GQEW). A tooth was defined as having a GQEW when all its canals were categorized as GQEW. RESULTS: From a total of 1867 root canals, overfilling occurred in 235 (12.6%), adequate filling length in 1152 (61.7%), underfilling in 466 (25.0%) and no filling in 12 (0.6%). Of the 1867 root canals, 710 (38.0%) demonstrated complete obturation and 1157 (62%) demonstrated incomplete obturation. GQEW was found in 650 (34.8%) root canals and 329 (30.3%) teeth. The percentage of teeth with GQEW in hospital cases (38.1%) was significantly greater (P < 0.001) than that in private clinic cases (24.3%). In addition, the frequency of teeth with GQEW in the anterior teeth (40.4%) or in the premolars (33%) was significantly greater (P < 0.001) than that in the molars (18.4%). CONCLUSIONS: Approximately 70% of the teeth receiving RCT in Taiwan were either of inadequate filling length or sealing density.     

Effect of nitric oxide synthase inhibitor (L-NAME) on substance P-induced vasodilatation in the dental pulp

AIM: To investigate the vasodilator mechanisms of pulpal vessels, especially the involvement of nitric oxide (NO), during pulpal inflammation. METHODOLOGY: Eleven cats were prepared for intra-arterial administration of test agents through a lingual artery. The pulpal blood flow was measured by laser Doppler flowmetry from ipsilateral mandibular canine teeth. By using the NO synthase (NOS) inhibitor N(G)-nitro L-arginine methyl ester (L-NAME), the effects of L-NAME on various vasodilators, such as Substance P (SP)-, calcitonin-gene related peptide (CGRP)-, and papaverine-induced vasodilatation, were compared in vivo in 11 feline dental pulps. RESULTS: L-NAME pretreatment potentiates SP-induced vasodilatation for a duration of approximately 5 h. The increase of pulpal blood flow ranged from 91.47 to 109.91%, which was significantly different from SP injection alone (48.79%, P < 0.05). Other vasodilators such as CGRP and papaverine did not respond to L-NAME pretreatment. CONCLUSIONS: This study demonstrates that NOS inhibitor L-NAME administration alone has insignificant effects on pulpal blood flow, although L-NAME pretreatment can potentiate SP-induced vasodilatation, probably via increased activity in the enzyme guanylate cyclase. CGRP and papaverine did not respond to L-NAME pretreatment, indicating that they are not mediated via an endothelium-dependent mechanism.     

Influence of polymerization conditions on monomer elution and microhardness of autopolymerized polymethyl methacrylate resin

Residual monomer contents and surface hardness are important factors in determining the serviceability of provisional restorations. The intent of this study was to systemically evaluate the effects of curing conditions on provisional polymethyl methacrylate (PMMA) resins which utilize a free-radical polymerization reaction. Combinations of the three curing factors of temperature, pressure, curing environment (water/air) were adjusted during the fabrication of autopolymerized specimen disks. The initial hardness of tested materials was measured with a microhardness tester 1 h after disc fabrication, and the amounts of residual methyl methacrylate (MMA) released into water were analyzed by reverse-phase HPLC after 7 d of water immersion. Results from multiple regressions showed that curing temperature was the dominant factor in improving resin surface hardness, whereas curing in water was the key factor for reducing the quantity of residual monomer. The pressure factor, which was thought to be critical for managing autopolymerized resins, showed no significant influences on the properties tested. ANOVA results showed that provisional PMMA resins cured in hot water, with or without pressure, significantly reduced the amount of residual MMA elution (up to 80%) and increased the microhardness values (up to 50%).     

The rise and fall of the Latino dentist supply in California: implications for dental education

The purpose of this study was to determine the number of Latino dentists in California, identify the schools and countries where they were educated, and compare Latino dentist demographics with that of the state's new demographics. From the 2000 California Department of Consumer Affairs list of 25,273 dentists, we identified Latino U.S. dental graduates (USDGs) by "heavily Hispanic" surnames and Latino international dental graduates (IDGs) by country and school of graduation. From the 2000 U.S. census Public Use Microdata Sample (PUMS), we described Latino dentist characteristics such as Spanish language capacity and practice location. The number of Latino dentists acquiring licenses to practice in California has fallen dramatically, by nearly 80 percent, between 1983 and 2000. This decline is not merely an affirmative action issue; it results in an issue of access. Latino dentists are far more likely to speak Spanish and be located in a heavily Latino area than non-Latino dentists. Currently, although the supply of Latino dentists is dwindling, the Latino population is growing rapidly. In California and out-of-state schools, first-year matriculation of Latino USDG must increase. Further, non-Latino dentists should be prepared and given incentives to learn Spanish and locate practices in areas of need. The reintroduction of IDG Latino dentists needs to be seriously considered.     

Sliding reconstruction of the condyle using posterior border of mandibular ramus in patients with temporomandibular joint ankylosis

The traditional approach for ankylosis is gap arthroplasty or interpositional arthroplasty followed by reconstruction of the condyle using, for example, costochondral grafts. As these are non-pedicled grafts, there is eventual resorption with subsequent decrease in height of the ramus, facial asymmetry and deviated mouth opening. The authors have applied the method of total and partial sliding vertical osteotomy on the posterior border of the mandibular ramus for reconstruction of the mandible condyle as a pedicled graft for the correction of temporomandibular joint (TMJ) ankylosis. From 2004 to 2008, 18 patients who were diagnosed with TMJ ankylosis underwent operations for resection of the ankylosed condyle. Two methods were performed depending on the level of osteotomy on the posterior part of the mandibular ramus. All patients were followed-up for an average of 36 months (range 24-48 months). All patients showed apparent improved joint function with no cases of re-ankylosis. The results showed that sliding vertical osteotomy on the posterior border of the mandibular ramus seems to be an alternative and promising method for condylar reconstruction in patients with TMJ bony ankylosis.