Methodological Quality Assessment of Meta-analyses in Endodontics

Introduction

The objectives of this review were to assess the methodological quality of published meta-analyses related to endodontics using the assessment of multiple systematic reviews (AMSTAR) tool and to provide a follow-up to previously published reviews.

Occlusione dentale e prestazione sportiva: revisione della letteratura

Objectives

A search of PubMed was performed to evaluate the hypothesis that correct occlusion or the use of a splint can improve an athlete's performance.

Materials and methods

A search of PubMed based on the key words dental occlusion and sport and considering works published through February 2010 yielded 72 articles. For this review, we selected 12 of these whose main topic was athletes.

Results

For this review we considered two case-control studies, two reviews, seven pilot studies, and one article regarding the use of a mouthpiece in scuba divers.

Conclusions

It is clear that the muscles of the cranio cervico-mandibular district are involved in sports activities. It is still not clear whether insertion of a splint in the oral cavity can or cannot improve an athlete's performances: data on this issue are discordant. We can conclude that every athlete has to be evaluated individually with appropriate clinical and instrumental methods.     

A comparative mechanical and bone remodelling study of all-ceramic posterior inlay and onlay fixed partial dentures

Objectives

Comparative studies of bone remodelling and mechanical stresses between inlay and onlay fixed partial dentures (FPD) are rather limited. The purpose of this paper was to evaluate the biological consequence in posterior mandibular bone and the mechanical responses in these two different prosthetic configurations.

Methods

Three-dimensional (3D) finite element analysis (FEA) models are created to explore the mechanical responses for the inlay and onlay preparations within the same oral environment. Strain induced bone remodelling was simulated under mastication. The remodelling adopted herein relates the strain in the bone to the change of Hounsfield Unit (HU) value in proportion to the surface area density (SAD) of bony morphology, which allows directly correlating to clinical computerised tomography (CT) data.

Results

The results show that both FPD designs exhibit a similar resultant change in bone mineral density (BMD) though the onlay configuration leads to a more uniform distribution of bone density. The inlay design results in higher mechanical stresses whilst allowing preservation of healthy tooth structure.

Conclusions

This study provides an effective means to further clinical assessment and investigation into biomechanical responses and long-term restorative outcome with different FPD designs.

Clinical significance

Quantifying in vivo stress distributions associated with inlay/onlay FPDs can further supplement clinical investigations into prosthetic durability, FPD preparation techniques (i.e., taper angles, material development), consequent stress distributions and the ongoing biomechanical responses of mandibular bone.     

Antibacterial activity of Propolis versus conventional endodontic disinfectants against Enterococcus faecalis in infected dentinal tubules

Introduction

The antibacterial activity against Enterococcus faecalis of 2 propolis samples was investigated in a dentin block model, and their effectiveness was compared with that of established endodontic disinfectants, chlorhexidine (CHX) and calcium hydroxide [Ca(OH)₂].

Methods

Standardized dentin blocks were infected with E. faecalis ATCC 29212. The root canal space was filled with one of the ethanolic extracts of propolis (Artvin or Tekirda? mix [TM]), CHX 2%, Ca(OH)₂, or ethanol or phosphate-buffered saline for control. Canal dentin was sampled after 1 or 7 days by using a standard-size bur. The dentinal shavings were vortexed vigorously in phosphate-buffered saline, and aliquots were cultured on tryptone soy agar plates. Colonies were counted after 2 days of incubation. Statistical significance was set to 5%.

Results

All experimental agents significantly reduced the number of the cultivable bacteria. CHX was the most potent disinfectant at both times. Compared with the ethanol control, no significant reduction in the number of colonies was found for the propolis extracts at day 1; however, significant reduction was found at day 7. The 2 propolis samples were statistically similar to each other and to Ca(OH)₂, but the TM sample was also similar to CHX at day 7. This has been linked to the greater concentration of flavonoids, a group of antibacterially active compounds, in the TM sample as determined by gas chromatography-mass spectrometry analysis.

Conclusions

The antimicrobial activity of the propolis samples tested in this study was between Ca(OH)₂ and CHX. Both propolis samples were antimicrobially effective; however, their activity did not exceed CHX.     

An animal model to study regenerative endodontics

Introduction

A growing body of evidence is demonstrating the possibility for regeneration of tissues within the pulp space and continued root development in teeth with necrotic pulps and open apices. There are areas of research related to regenerative endodontics that need to be investigated in an animal model. The purpose of this study was to investigate ferret cuspid teeth as a model to investigate factors involved in regenerative endodontics.

Methods

Six young male ferrets between the ages of 36-133 days were used in this investigation. Each animal was anesthetized and perfused with 10% buffered formalin. Block sections including the mandibular and maxillary cuspid teeth and their surrounding periapical tissues were obtained, radiographed, decalcified, sectioned, and stained with hematoxylin-eosin to determine various stages of apical closure in these teeth.

Results

The permanent mandibular and maxillary cuspid teeth with open apices erupted approximately 50 days after birth. Initial signs of closure of the apical foramen in these teeth were observed between 90-110 days. Complete apical closure was observed in the cuspid teeth when the animals were 133 days old.

Conclusions

Based on the experiment, ferret cuspid teeth can be used to investigate various factors involved in regenerative endodontics that cannot be tested in human subjects. The most appropriate time to conduct the experiments would be when the ferrets are between the ages of 50 and 90 days.     

Methodological and Reporting Quality of Systematic Reviews and Meta-analyses in Endodontics

Introduction

The aim of this systematic review (SR) was to evaluate the quality of SRs and meta-analyses (MAs) in endodontics.

Prevalence and distribution of serotype-specific genotypes of Aggregatibacter actinomycetemcomitans in chronic periodontitis Brazilian subjects

Objective

Previous studies have suggested that Aggregatibacter actinomycetemcomitans is involved in the aetiology of aggressive periodontitis as well as chronic periodontitis. In addition, some authors have also reported that serotype-specific antigens of A. actinomycetemcomitans determine the severity of disease. This study aimed to elucidate the prevalence of A. actinomycetemcomitans and the distribution of A. actinomycetemcomitans serotypes in Brazilian subjects with chronic periodontitis.

Design

A total of 486 individuals were enrolled in this survey. All patients received clinical examinations that included periodontal pocket depth, clinical attachment loss, plaque, and gingival indexes. Subgingival samples were taken for microbial analysis. The genomic DNA of A. actinomycetemcomitans was provided by PCR.

Results

Out of 486 subjects examined, A. actinomycetemcomitans was isolated in 85 (17.5%) individuals. Out of 85 positive samples, 68 were infected by at least 1 serotype, 7 by mixed infection, and 10 were non-serotyped. Serotypes d and f were not detected. Serotype c showed the highest prevalence (52.9%), followed by serotype a (31.8%).

Conclusions

Intragroup analysis revealed that, in slight/moderate periodontitis, serotypes c and a were significantly more prevalent than serotypes b and d-f; the prevalence of serotype c in severe periodontitis was significantly greater than that of serotypes a and b. Our data were similar in Asian and Eurasian populations.     

Influence of gender on the metabolism of alcohols in human saliva in vitro

Objective

The aim of this study was to investigate possible gender differences in salivary metabolism of two alcohols, ethanol and 2-propanol. Ethanol and its metabolite acetaldehyde may play important roles in tumour development, especially in the upper digestive tract. 2-Propanol is tested to elucidate our previous findings, where gender-specific differences in salivary acetone levels were seen after exposure to this alcohol.

Design

Saliva was collected from 25 females and 22 males for in vitro exposure to 2-propanol. In the experiments with ethanol, saliva samples were collected from 17 females and 18 males. The saliva was exposed in vitro to 2-propanol or ethanol. The metabolites acetone, derived from 2-propanol, and acetaldehyde, derived from ethanol, together with the maternal substance were analysed by headspace gas chromatography.

Results

No differences related to gender, age, medication or tobacco intake in the acetone concentration in the saliva samples were found. Gender, age or tobacco intake did not result in difference in the production of acetaldehyde in saliva. However, in the pre-exposure samples the men had a significantly higher concentration of acetaldehyde compared to the women (p = 0.04). Also, there was a tendency (p = 0.05) to higher concentrations of acetaldehyde in the samples (at 1 mM ethanol exposure) from subjects who take medications.

Conclusion

No gender difference in the metabolism of 2-propanol and ethanol in human saliva in vitro were found.     

ElectroBond application may improve wetting characteristics of etched dentine

Objective

To assess the efficacy of an electrically assisted application technique on dentine wettability (water contact angle measurements) and to determine the promoted surface roughness of dentine after applying 37% phosphoric acid etching, a self-etching primer or a self-etching adhesive system.

Methods

Wettability was assessed on 30 caries-free extracted human third molars. Specimens were sectioned parallel to the occlusal surface to expose moderately deep dentine and ground flat (water-wet 180-grit SiC) to provide uniform flat surfaces. 37% H₃PO₄, Clearfil SE Bond (CSEB) primer or Prompt-L-Pop (PLP) adhesive system were applied on dentine surfaces. In half of the specimens, the electric impulse-assisted application technique/ElectroBond-assisted application was followed. Contact angle measurements were performed to assess wettability using the Axisymmetric Drop Shape Analysis technique. Additional surfaces were conditioned for atomic force microscopy (AFM) analysis. Two-way ANOVA, Student's t and Student-Newman-Keuls tests were performed (P < 0.05).

Results

PLP-treated dentine showed the highest intertubular roughness and the lowest dentine wettability. ElectroBond application reduced water contact angles when dentine was treated with H₃PO₄ or Clearfil SE Bond primer, but not when dentine was treated with PLP.

Conclusions

The use of electric current improved wettability of dentine surface following application of phosphoric acid and a mild self-etch primer, but not self-etch adhesive.     

Micro-computed tomography evaluation of the preparation of long oval root canals in mandibular molars with the self-adjusting file

Introduction

The aim of this study was to assess the shaping potential of a novel nickel-titanium instrument, the self-adjusting file (SAF), in long oval root canals in distal roots in mandibular molars.

Methods

Twenty mandibular molars with long oval distal root canals were selected and scanned preoperatively and postoperatively by using micro-computed tomography at an original resolution of 20 μm. Canals were shaped with the SAF, three-dimensionally reconstructed, and evaluated for volume, surface area, canal transportation, and prepared surface. Data were statistically contrasted by using paired t tests and regression analysis.

Results

Preoperatively, canal volume was 7.73 ± 2.13 mm³, and canal area was 42.83 ± 8.14 mm². Volumes and surface areas increased significantly (P < .001) by 4.84 ± 1.73 mm³ and 3.34 ± 1.73 mm², respectively, and no gross preparation errors were detected. Unprepared canal surface varied between individual canals, and mean unprepared surface was 23.5% ± 8.9%. Prepared areas were significantly larger compared with rotary canal preparation done in a previous study. Canal transportation scores were higher in the coronal root canal third (106 ± 50 μm) compared with the apical third (81 ± 49 μm).

Conclusions

In vitro, preparation of long oval-shaped root canals in mandibular molars with the SAF was effective and safe. Moreover, shapes generated with the SAF were more complete compared with rotary canal preparation.     

Effects of surface pre-reacted glass-ionomer fillers on mineral induction by phosphoprotein

Objectives

The aim of this study was to evaluate the mineralizing potential of ions released from surface pre-reacted glass-ionomer (S-PRG) fillers on mineral induction by phosphoprotein in vitro.

Methods

Phosvitin was used as a model of dentin phosphoprotein in this study. Phosvitin was immobilized on agarose beads with divinyl sulfone. Five aliquots of phosvitin-immobilized agarose beads were incubated in control or experimental mineralizing solution. The experimental mineralizing solutions were made from eluates of resin filled with S-PRG fillers. The beads were incubated at 37 °C in a shaking water bath, and aliquots were taken at several time points during the incubation. Then the beads were analyzed for calcium by atomic absorption spectrometry.

Results

Phosvitin-immobilized agarose beads induced mineral formation after incubation for 5.3 h in the metastable solution without ions eluted from S-PRG fillers. Undiluted eluates significantly reduced mineral induction time. SEM observation and X-ray diffraction revealed larger apatite crystals on the beads incubated with eluates of S-PRG fillers than with the control.

Conclusions

S-PRG fillers may play a role in mineral induction.     

Degradation resistance of ormocer- and dimethacrylate-based matrices with different filler contents

Objectives

To investigate the influence of matrix and filler content on degradation resistance of an experimental pure-ormocer and an dimethacrylate-based composite derived from a commercially available material.

Materials and methods

A dimethacrylate- Grandio (GR) and a model pure ormocer-based-matrix ORMOCER (ORM) were used. Each material had three different types according to their filler content (% w/w): regular (87% and 86%), flowable (80% and 79%) and fissure sealer (70% and 69%) for GR and ORM respectively. Disc-shaped (1 mm thickness × 10 mm diameter) samples were prepared for each material (n = 6). Water sorption and solubility tests were adapted from ISO4049. To evaluate porosity, specimens were scanned at a resolution of 19.4 μm and 3D reconstructions were made. The volume ratio of pores in the specimens were calculated and expressed as percentages. The results were submitted to 2-way ANOVA (factors: matrix and filler content) and Tukey post-hoc statistic test (p = 0.05).

Results

Filler content influenced the water sorption for the ormocer-matrix and the water solubility for the dimethacrylates. ORMOCER regular was a less porous material compared to flowable and sealer formulations. On the other hand, the filler content had no effect on porosity for Grandio.

Conclusion

Modifications made in the pure ormocer-matrix formulation were not significantly important to produce a more water-stable material compared to the dimethacrylate-matrix composite materials.     

Microleakage after thermocycling of cemented crowns—A meta-analysis

Objectives

Microleakage testing of dental materials is a commonly accepted evaluation technique of margin integrity. Thermocycling has been utilized by many researchers to study the influence of temperature extremes on the marginal gap of cemented restorations. The aim of this investigation was to analyze microleakage data on cemented crowns, published in the dental literature until Dec 2009, to identify methodological factors that might potentially affect the results of in vitro microleakage tests and to compare the results.

Methods

The following databases were included: Ovid MEDLINE(R) In-Process & Other Non-Indexed Citations and Ovid MEDLINE(R) 1950 to Present, Ovid-MEDLINE(R) 1950 to Present with Daily Update, EMBASE, EBM Reviews - Cochrane Database of Systematic Reviews and Pub Med. The search was limited to articles in English, French, Italian and German published until the end of 2009. Classical reviews, comments, animal studies, in vivo articles and studies investigating restorative materials or milk teeth were excluded. 33 different studies were finally selected. The studies were entered in a database and compared using selected literature criteria: sample, restoration procedures, thermocycling and mechanical cycling, evaluation method. For statistical analysis only 16 studies could be applied.

Results

It was not possible to make a quantitative synthesis of most of the data, due to the heterogeneity of the studies concerning methods, treatment and outcome variables. Comparing the main groups of materials (ceramics, gold alloys and base metal alloys), no significant difference in the proportion of teeth without microleakage was found. Furthermore no significant difference in the proportion of teeth showing microleakage less than two third of the wall or teeth showing microleakage including the entire wall was found. Using the mean values in the meta-analysis instead of the proportions does not change the results. Confidence intervals could only be calculated for two materials (gold alloy, metal alloy). No difference between materials was found.

Significance

Comparison of the results from different studies is critical, since there are no generally accepted standards for experimental parameters, such as type and concentration of the storage solution, time of storage, temperature during storage, type and duration of thermal cycling and/or mechanical cycling, and the scoring criteria. There is lack of standardization of experimental conditions, which would ensure confidence in the studies and would further allow better comparability of various results.     

Hard tissue-forming potential of stem/progenitor cells in human dental follicle and dental papilla

Objective

The existence of stem/progenitor cells in dental tissue has been suggested but their characterization in the human tooth germ remains elusive. The purpose of this study was to investigate these cells in human dental follicles and dental papillae at the crown-forming stage and compare their potential for hard tissue formation.

Design

We used dental follicle cells (DFCs) and dental papilla cells (DPCs) derived from dental follicles and dental papillae at the crown-forming stage and compared their proliferative capacity, cell surface antigens and ability to form hard tissue in vitro and in vivo.

Results

Both DFCs and DPCs had extensive proliferation ability, expressed similar cell surface antigens and were capable of forming hard tissue in vivo as well as in vitro. However, there were two differences between DFCs and DPCs. First, DPCs had a significantly higher calcium accumulation than that in DFCs. Second, DFCs expressed a cementoblast marker, whereas DPCs expressed an odontoblast marker.

Conclusions

We propose that dental follicles and dental papillae at the crown-forming stage contain different types of stem/progenitor cells and may have hard tissue-forming ability in a possibly origin-specific lineage direction.     

The role of salivary factors in persistent oral carriage of Candida in humans

Background

Candida albicans is a commensal oral yeast in approximately one-third to one-half of the healthy population. To date, there are no studies investigating the multiple anti-candidal salivary constituents of healthy individuals with either nil or, consistent oral yeast carriage.

Objective

To compare the composition and anti-candidal activity in stimulated whole saliva of healthy ‘consistent’ oral Candida carriers with Candida-free individuals.

Methods

A sub-sample of 22 consistent, Candida-free individuals and 10 consistent Candida carriers were recruited from a 12 months screening study investigating oral Candida carriage in 97 healthy patients treated by fixed orthodontic appliances. Unstimulated and stimulated saliva samples were collected. The following salivary attributes were measured using standard methodology: the flow rate, pH, lysozyme, lactoferrin and IgA concentration and, the degree of inhibition of blastoconidial growth and blastospore germination.

Results

Saliva from the Candida-free individuals showed 20.2% higher inhibition of blastoconidial growth (p < 0.05) of a reference strain of Candida albicans. No significant differences between the other salivary attributes of the two groups were found.

Conclusion

The fact that saliva of Candida-free individuals significantly inhibited the blastoconidial growth more than Candida-carriers (p < 0.05) suggests that saliva may play a role in modulating oral candidal populations in health. Further studies, with a larger cohort are needed to confirm these findings and determine the factors that confer enhanced salivary anti-candidal activity.     

Cutting Efficiency of Twisted versus Machined Nickel-Titanium Endodontic Files

Introduction

The purpose of this study was to compare the efficacy of the cutting ability of two different instruments, concerning changes in the dentin thickness removed and root canal volume, by using multislice computed tomography scanning.

Methods

Thirty single-rooted mandibular premolars were divided into two equal groups according to the preparation system used: the twisted file (TF) and ProTaper (Dentsply Maillefer, Ballaigues, Swizerland). Dentin thickness along the whole length of the root canal and canal volume were measured before and after instrumentation by using multislice computed tomography scanning and image analysis software.

Results

ProTaper removed significantly more dentin from the mesiodistal and buccolingual directions of the root canal than the TF (P < .05). No significant difference was recorded for the changes in root canal volume between the two systems (P > .05).

Conclusions

The TF system was found to cut dentin efficiently with more uniform cutting than ProTaper system.     

Clinical and microstructural aberrations of enamel of deciduous and permanent teeth in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy

Objective

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) causes multiple endocrine deficiencies, oral candidiasis and different forms of ectodermal dystrophy including enamel hypoplasia, documented in permanent teeth. Our purpose was to examine dental aberrations associated with APECED, including possible manifestations in primary teeth.

Design

We studied clinically, radiographically, and by scanning electron microscopy (SEM) teeth of children belonging to two APECED families with different mutations in the AIRE gene.

Results

In addition to enamel defects in the permanent teeth we observed hypoplastic pits and hypomaturated patches in the deciduous teeth with underlying changes in the prismatic ultrastructure. The enamel of the permanent molars exhibited a layered arrangement with included whirl-like formations.

Conclusions

Our findings confirm that APECED causes enamel defects that are individually but chronologically distributed, and can alter enamel development early enough to affect deciduous teeth.     

Biomechanical aspects of prosthetic treatment of structurally compromised teeth

Purpose

This article presents clinical guidelines for restoring structurally compromised teeth and dentitions to reduce the risk for fatigue-caused failures in connection with prosthetic reconstructions.

Materials and methods

Based on the best scientific evidence available and clinical expertise acquired through experience and practice, biomechanical principles are elucidated from a prosthetic aspect.

Results

In prosthetic treatment in the structurally compromised dentition, all efforts need to be focused on protecting the abutments and reconstruction from future fatigue failures. A modified, “therapeutic” occlusion to avoid nonaxial forces may then be prudent.

Conclusion

By lending the prosthesis a favorable occlusal design, the nonaxial forces may be markedly reduced, and the teeth, cement, and restorative materials will be less susceptible to fatigue failures.—Reprinted with permission of Quintessence Publishing.     

Molecular characterization of Streptococcus mutans strains containing the cnm gene encoding a collagen-binding adhesin

Objective

Streptococcus mutans, known to be a major pathogen of dental caries, is also considered to cause infective endocarditis. Its 120-kDa Cnm protein binds to type I collagen, which may be a potential virulence factor. In this study, we characterized S. mutans clinical strains focusing on the cnm gene encoding Cnm.

Design

A total of 528 S. mutans strains isolated from Japanese, Finnish, and Thai subjects were investigated. Using molecular techniques, the distribution frequency of cnm-positive strains and location of the inserted cnm were analyzed. Furthermore, isogenic mutant strains were constructed by inactivation of the cnm gene, then their biological properties of collagen-binding and glucan-binding were evaluated. Southern hybridization of the genes encoding glucan-binding proteins was also performed.

Results

The distribution frequency of cnm-positive strains from Thai subjects was 12%, similar to that previously reported for Japanese and Finnish subjects. Furthermore, the location of insertion of cnm was the same in all cnm-positive clinical isolates. As for the cnm-inactivated mutant strains constructed from 28 clinical isolates, their collagen-binding activity was negligible. In addition, glucan-binding activity in the cnm-positive clinical isolates was significantly reduced and corresponded to a lack of gbpA encoding glucan-binding protein A.

Conclusions

Our results indicate that strains with cnm genes, the most crucial factor for the collagen-binding property of S. mutans, are detectable at similar frequencies over several different geographic locations. In addition, the common properties of these strains are a high level of collagen-binding activity and tendency for a low level of glucan-binding activity.