Lasers for caries removal in deciduous and permanent teeth.

BACKGROUND: Despite considerable improvements in oral health, dental caries continue to be a public health issue. The most frequently used, and universally accepted technique, to remove caries is through mechanical ablation of decayed tissues by means of rotating drills (diamond or tungsten carbide, or both). In the past few decades, the introduction of adhesive filling materials (resin composites) has affected cavity filling procedures by reducing its retention needs, with advantages for dental tissue conservation. Consequently, new minimally invasive strategies were introduced into dental practice, such as the use of lasers to perform highly controlled tissue ablation. Laser use has also raised expectations of limiting pain and discomfort compared to using drills, as well as overcoming drill phobia. OBJECTIVES: The main objective of the review was to compare the effects of laser-based methods to conventional mechanical methods for removing dental caries in deciduous and permanent teeth. SEARCH METHODS: We searched the following electronic databases: Cochrane Oral Health's Trials Register (searched 22 June 2016), Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 5) in the Cochrane Library (searched 22 June 2016), MEDLINE Ovid (1946 to 22 June 2016), Embase Ovid (1980 to 22 June 2016), ProQuest Dissertations and Theses (1980 to 22 June 2016), Zetoc (limited to conference proceedings) (1993 to 22 June 2016), and ISI Web of Knowledge (limited to conference proceedings) (1990 to 22 June 2016). We checked the reference lists of relevant articles to identify additional studies. We searched the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform for ongoing trials. SELECTION CRITERIA: We included randomised controlled trials, split-mouth trials and cluster-randomised trials (irrespective of their language) comparing laser therapy to drill ablation of caries. We included participants of any age (children, adolescents and adults). DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles and abstracts of citations identified by the review search strategy. Two review authors independently evaluated the full text of relevant primary studies, assessed risk of bias and extracted data. We used standard methodological procedures expected by Cochrane. MAIN RESULTS: We included nine randomised trials, published between 1998 and 2014, involving 662 participants. The population consisted of both children and adolescents in four trials, only adults in four trials, and both children/adolescents and adults in one trial. Four studies examined only permanent teeth, and five studies evaluated both deciduous and permanent teeth. Six trials used Er:YAG (erbium-doped yttrium aluminium garnet) lasers, two trials employed Er,Cr:YSGG (erbium, chromium: yttrium-scandium-gallium-garnet) lasers, and one trial used Nd:YAG (neodymium-doped yttrium aluminium garnet) laser.Overall, the trials had small sample sizes, and the majority were at unclear or high risk of bias. The primary outcomes were evaluated in a limited number of trials (removal of caries (four trials (but only two reported quantitative data)); episodes of pain (five studies)). There was insufficient evidence to suggest that either lasers or drill were better at caries removal (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.99 to 1.01; 2 studies; 256 treated caries; P = 0.75; I2 = 0%; low-quality evidence).The incidence of moderate or high pain was greater in the drill group compared to the laser group (RR 0.40, 95% CI 0.28 to 0.57; 2 studies; 143 participants; P < 0.001; I2 = 50%). Similarly, the need for anaesthesia was significantly higher in the drill group than in the laser group (RR 0.25, 95% CI 0.10 to 0.65; 3 studies; 217 children/adolescents; P = 0.004; I2 = 0%).In terms of marginal integrity of restoration, there was no evidence of a difference between laser and drill comparisons evaluated at 6 months (RR 1.00, 95% CI 0.21 to 4.78; 3 studies), 1 year (RR 1.59, 95% CI 0.34 to 7.38; 2 studies), or 2 years (RR 1.00, 95% CI 0.21 to 4.74; 1 study).There was no evidence of a difference for durability of restoration between laser therapy or drill at 6 months' follow-up (RR 2.40, 95% CI 0.65 to 8.77; 4 studies), at 1 year (RR 1.40, 95% CI 0.29 to 6.78; 2 studies) or at 2 years' follow-up (RR 0.50, 95% CI 0.02 to 14.60; 1 study).Only two trials investigated the recurrence of caries, but no events occurred during 6 months' follow-up.There was insufficient evidence of a difference between laser or drill in terms of pulpal inflammation or necrosis at 1 week (RR 1.51, 95% CI 0.26 to 8.75; 3 studies) and at 6 months (RR 0.99, 95% CI 0.10 to 9.41; 2 studies). AUTHORS' CONCLUSIONS: Given the low quality of the body of evidence, we concluded that evidence was insufficient to support the use of laser as an alternative to traditional drill therapy for caries removal. We found some evidence in favour of laser therapy for pain control, need of anaesthesia and patient discomfort, but, again, the body of evidence was of low quality. Additional well-designed, randomised trials investigating the most relevant outcomes are needed.

Mechanical effect of static loading on endodontically treated teeth restored with fiber-reinforced posts.

The aim of this study was to investigate the mechanical behavior of a dental system built up with fiber-reinforced composite (FRC) endodontic posts with different types of fibers and two cements (the first one used with a primer, the second one without it). Six FRC posts were used. Each system was characterized in terms of structural efficiency under external applied loads similar to masticatory forces. An oblique force was applied and stiffness and maximum load data were obtained. The same test was used for the dentine. The systems were analyzed by scanning electron microscope (SEM) to investigate the surface of the post and inner surface of root canal after failure. The mechanical tests showed that load values in dental systems depend on the post material and used cement. The highest load (281 ± 59 N) was observed for the conical glass fiber posts in the cement without primer. There was a 50 and 85% increase in the maximum load for two of the conical posts with glass fibers and a 229% increase for the carbon fiber posts in the cement without primer as compared with the cement with primer. Moreover, almost all the studied systems showed fracture resistances higher than the typical masticatory loads. The microscopic analysis underlined the good adhesion of the second cement at the interfaces between dentine and post. The mechanical tests confirmed that the strength of the dental systems subjected to masticatory loads was strictly related to the bond at the interface post/cement and cement/dentine.

Compressive and flexural behaviour of fibre reinforced endodontic posts.

OBJECTIVES: The aim of this study was to investigate the mechanical properties of five types of fibre-reinforced composite (FRC) posts and compare them with traditional metal post. METHODS: Five FRC posts and a metallic post having different geometry and type of fibre (glass, carbon or quartz fibre) were loaded to failure in compression and bending. The transverse sections of FRC posts were observed using SEM to evaluate the fracture mode and the percentage of fibres (compared with burn-off test). Densities and voids content were also evaluated. RESULTS: Mechanical results were subjected to a one-way ANOVA and Tukey test (p<0.05). In compression, quartz fibre posts exhibited the greater maximum load and ultimate strength, carbon fibre posts showed a poor compressive behaviour. All posts had similar compressive moduli. Carbon posts showed the highest flexural properties (p<0.0001) while glass posts the greater maximum load. The fracture load values correlated to the diameters of posts showed a parabolic behaviour. The flexural strengths of all posts were four and seven times higher than dentine. The elastic moduli of almost all posts were similar to dentine. The compressive strengths were lower than flexural strengths. The fibre diameters ranged from 5.2 to 26 µm, the volume percentage of fibres was about 64%. The content of voids of some posts lower their mechanical behaviour. CONCLUSIONS: Compressive properties of FRC posts were lower than in bending. The flexural properties of FRC posts were higher than the metal post and similar to dentine. The mechanical behaviour is influenced by voids.