A preliminary evaluation into the performance of posterior resin bonded cast metal restorations (adhesive onlays).

Posterior resin bonded cast metal restorations (adhesive onlays) were used in a variety of clinical scenarios including: management of tooth wear and cracked tooth, as retainers for fixed bridge work, for correction of the occlusal plane and in providing cuspal coverage following endodontic treatment. The mean length in service for the examined onlays was 42 months, with a range of 9-75 months. Two restorations in two patients failed resulting in an overall success of 94%. Patient satisfaction was high at 95%. Such restorations seem to be a viable option for managing a number of clinical scenarios.

Effect of reduced exposure times on the microhardness of nanocomposites polymerized by QTH and second-generation LED curing lights.

This study investigated the effectiveness of polymerization of various curing regimes on five nanocomposite restorative materials­Z350, Grandio, Clearfil Majesty Esthetic, Ice and Tetric EvoCeram­by utilizing microhardness measurements. Five (n=5) disc-shaped specimens of each material were subjected to one of three curing regimes: curing with a halogen light for 20 seconds, curing with an LED light for 20 seconds and curing with an LED light for 10 seconds. Immediately following curing, hardness measurements were made with a Vickers indenter at five different locations on both the top and bottom surfaces of each disc. The mean for each surface was calculated. Data were analyzed using a one-way ANOVA and post-hoc Tukey HSD (α=0.05). The results demonstrated that among the Z350 composite samples, top and bottom microhardness values showed no statistical differences when cured with the halogen 20 second or LED 20 second regimes (p>0.05). Comparison of the top and bottom values of discs cured with the LED 10 second regime demonstrated significant differences (p<0.0001). Grandio samples cured with the halogen 20 second regime showed no statistical differences between top and bottom microhardness values (p>0.05); however, the bottom values of Grandio discs cured with the LED 20 second and 10 second regimes were significantly lower when compared with top surface values (p=0.001 and p<0.0001, respectively). Clearfil Majesty Esthetic, Ice and Tetric Evo Ceram samples cured with the halogen 20 second regime produced significantly lower bottom microhardness values, while both LED regimes produced top and bottom surfaces that were statistically comparable. The conclusion may be drawn that LED 10 second curing regimes were insufficient to cure Z350 and Grandio, while they were adequate for curing Clearfil Majesty Esthetic, Ice and Tetric EvoCeram.

Effect of Reduced Exposure Times on the Microhardness of Nanocomposites Polymerized by QTH and Second-generation LED Curing Lights

This study investigated the effectiveness of polymerization of various curing regimes on five nanocomposite restorative materials­Z350, Grandio, Clearfil Majesty Esthetic, Ice and Tetric EvoCeram­by utilizingmicrohardnessmeasurements. Five (n=5) disc-shaped specimens of each material were subjected to one of three curing regimes: curing with a halogen light for 20 seconds, curing with an LED light for 20 seconds and curing with an LED light for 10 seconds. Immediately following curing, hardness measurements were made with a Vickers indenter at five different locations on both the top and bottom surfaces of each disc. The mean for each surface was calculated. Data were analyzed using a one-way ANOVA and post-hoc Tukey HSD (α=0.05). The results demonstrated that among the Z350 composite samples, top and bottom microhardness values showed no statistical differences when cured with the halogen 20 second or LED 20 second regimes (p>0.05). Comparison of the top and bottom values of discs cured with the LED 10 second regime demonstrated significant differences (p<0.0001). Grandio samples cured with the halogen 20 second regime showed no statistical differences between top and bottom microhardness values (p>0.05); however, the bottom values of Grandio discs cured with the LED 20 second and 10 second regimes were significantly lowerwhen comparedwith top surface values (p=0.001 and p<0.0001, respectively). Clearfil Majesty Esthetic, Ice and Tetric EvoCeram samples cured with the halogen 20 second regime produced significantly lower bottom microhardness values, while both LED regimes produced top and bottom surfaces that were statistically comparable. The conclusion may be drawn that LED 10 second curing regimes were insufficient to cure Z350 and Grandio, while they were adequate for curing Clearfil Majesty Esthetic, Ice and Tetric EvoCeram.

An in vitro evaluation of shear bond strengths of glass ionomer/amalgam combinations

Purpose: The purpose of this study was to assess the shear bond strength of amalgam when bonded to dentine with various cements. Materials and Methods: Eighty human molars were divided into five groups and ground dentine surfaces treated, with one of five cements (Fuji I, Vitrebond, Rely X, Fuji II and Panavia F). Spherical amalgam (Tytin) was condensed onto the unset cement and shear bond strengths were measured after one week. Results: The mean shear bond strength of Panavia F (25.3 MPa) was significantly higher compared with Fuji I (16.8 MPa), Fuji II (10.3 MPa) and Vitrebond (5.1 MPa) however there was no significant difference with Rely X (19.0 MPa). Conclusion: The combination of a resin modified glass ionomer luting cement with a spherical alloy may enhance bonding of amalgam to dentine.

Reduction in intracanal bacteria during root canal preparation with and without apical enlargement.

AIM: To compare in vitro intracanal bacterial reduction using nickel-titanium rotary instruments with and without apical enlargement. METHODOLOGY: Thirty-eight palatal roots of maxillary molar teeth, with mature apices were subdivided according to lengths and then randomly assigned to two experimental and one control groups. The roots were sterilized and then reinfected with Enterococcus faecalis, which served as a bacteriological marker. All roots in the experimental groups were prepared in a step-down sequence with engine-driven GT rotary files at 350 rpm. In experimental group A (n = 16) additional apical enlargement to ISO size 35 was performed. In group B (n = 16) a serial step-back technique was followed with no apical enlargement. This was combined in groups A and B with irrigation with NaOCl and EDTA. In the control group (group C, n = 6) irrigation only was carried out, with no mechanical preparation. Samples were then taken from the root canals to determine the numbers of remaining bacteria. RESULTS: In groups A and B, 15 (94%) and 13 (81%) specimens were rendered bacteria-free, respectively. In the control group C none of the specimens were bacteria-free. There was a significant difference (P < 0.001) in the antibacterial effects of experimental and control regimens. There was, however, no significant difference (P = 0.276) between the preparation methods used in the experimental groups. CONCLUSIONS: There was no significant difference in intracanal bacterial reduction when Ni-Ti GT rotary preparation with NaOCl and EDTA irrigation was used with or without apical enlargement preparation technique. It may therefore not be necessary to remove dentine in the apical part of the root canal when a suitable coronal taper is achieved to allow satisfactory irrigation of the root canal system with antimicrobial agents.

Management of teeth requiring root canal treatment and views on continuing professional education in endodontics by dental practitioners in Trinidad and Tobago [abstract]

Many of the new materials and techniques used in endodontics (root canal treatment) require considerable practice to master and many require continuing education courses to allow formal instruction. Nothing is known regarding techniques employed and views on continuing professional education (CPE) in endodotics by dentists in Trinidad and Tobago. With the shift toward evidence-based dentistry and rising patient expectation of quality oral health care, a survey was conducted to describe these issues. A self-administered postal questionnaire was sent to all registered dentists in Trinidad and Tobago. Seventy dentists responded after two mailings. Most respondents worked primarily in private practice (85.5 percent). Years since qualification ranged from 2 to 45 years and 54.3 percent were qualified for more than 10 years. Most frequent treatment of an acute dental abcess involved opening, preparing the canal(s), dressing and prescribing antibiotics (40 percent). Forty-one respondents (58.6 percent) ocassionally completed root canal treatment in a single visit. Isolation of the tooth for molar root treatment always caused difficulty for thirty-five respondents (50 percent) and rubber dam isolation was used routinely by only nine respondents (12.9 percent). Most respondents either filed (20 percent) or reamed (18 .6 percent) for canal preparation usually using K files. Thirty-three respondents (47 percent) used sodium hypochlorite to irrigate the tooth and thirty-one (44.3 percent) used cold lateral condensation of gutta percha to obturate. Thirty-four respondents (48.6 percent) subscribed to professional journals and sixty-seven (95.7 percent) had attended some form of Continuing Professional Education. Sixty-seven (95.7 percent) of respondents would attend CPE in endodontics if available in Trinidad and Tobago, with most (72.9 percent) preferring a lecture/seminar format addressing problem-solving and new techniques. Respondents to this survey showed use of a wide range of techniques and materials but still expressed considerable interest in developing their skills in endodontics through formal CPE. (AU)

Molecular identification of microorganisms from endodontic infections.

A relatively wide range of bacteria have been isolated from root canals using standard culture techniques. However, only 50% of the bacteria in the oral cavity are cultivable (S. S. Socransky et al., Arch. Oral Biol. 8:278-280, 1963); hence, bacterial diversity in endodontic infections is underestimated. This study used a PCR-based 16S rRNA gene assay, followed by cloning and sequencing of 16S rRNA amplicons from a small subset of samples to assess the diversity of bacteria present in infected root canals. A total of 41 clinical samples from 15 de novo and 26 refractory cases of endodontic infections were assessed. Of these samples, 44% were positive by culture and 68% were positive by PCR. Eight samples were selected for further analysis. Of these, the two de novo cases yielded sequences related to those of the genera Enterococcus, Lactobacillus, Propionibacterium, and Streptococcus and two clones were related to previously uncultivated bacteria, while the sinus-associated, de novo case yielded sequences related to those of the genera Lactobacillus, Pantoea, Prevotella, and Selenomonas. The five refractory cases produced clones which were related to the genera Capnocytophaga, Cytophaga, Dialister, Eubacterium, Fusobacterium, Gemella, Mogibacterium, Peptostreptococcus, Prevotella, Propionibacterium, Selenomonas, Solobacterium, Streptococcus, and Veillonella and two clones representing previously uncultivated bacteria. The phylogenetic positions of several clones associated with the Clostridiaceae and Sporomusa subgroups of the Firmicutes grouping are also shown. This study demonstrates that molecular techniques can detect the presence of bacteria in endodontic infections when culture techniques yield a negative result and can be used to identify a wider range of endodontic-infection-related bacteria including the presence of previously unidentified or unculturable bacteria.