Structural Integrity Evaluation of Large MOD Restorations Fabricated With a Bulk-Fill and a CAD/CAM Resin Composite Material.

AIMS: To evaluate the effect of two composite restorative techniques (direct bulk fill vs indirect CAD/CAM) on the fracture resistance and mode of fracture of extended mesio-occlusal-distal (MOD) cavity preparations. METHODS: Fifty-one sound human mandibular third molars were divided into three groups (n=17). Extended bucco-lingual MOD cavities were prepared. Teeth in group 1 were restored with a bulk-fill resin composite (Filtek Bulk-Fill Posterior Restorative), teeth in group 2 were restored with composite computer-aided design/computer-aided manufacturing (CAD/CAM) inlays (Lava Ultimate), and teeth in group 3 served as control and remained intact. All specimens were submitted to thermocycling, and a fracture resistance test was performed using a Universal testing machine (0.5 mm/min). Mode of fracture was classified into five types. One-way analysis of variance and the Duncan test were used to analyze the fracture load data at a significance level of α = 0.05. A chi-square test was used for the analysis of fracture mode between the restorative groups. RESULTS: Statistical analysis showed significant differences in fracture resistance among the experimental groups. The teeth restored with the bulk-fill composite exhibited lower fracture resistance (1285.3±655.0 N) when compared to the teeth restored with the composite CAD/CAM inlays (1869.8±529.4 N) (p<0.05). Mode of fracture showed the same distribution between the restorative groups. CONCLUSIONS: Although both types of restorations failed at loads larger than those found in the oral cavity, the CAD/CAM composite inlays increased the fracture resistance of teeth with large MOD cavities when compared to direct bulk-fill composite restorations. The majority of fracture types were intraorally repairable for both restorative techniques.

Intra-pulpal temperature rise of different tooth types during dental bleaching supported by an Er,Cr:YSGG laser. A pilot study.

The purpose of this pilot in vitro study was to evaluate the temperature increase in the pulp chamber of the teeth, during Er,Cr:YSGG bleaching, as well as to show which teeth are the most susceptible in terms of pulp temperature increase during laser-activated bleaching treatment. Although Er:YAG studies have been published on this subject, it is the first time Er,Cr:YSGG wavelength is tested. Fifteen teeth were tested--3 each of the following--(maxillary central incisors, lateral incisors, canines, premolars and mandibular incisors). The bleaching procedure comprised an Er,Cr:YSGG laser (2780 nm, Waterlase MD, Biolase, USA) and a yellow-coloured bleaching agent with a concentration of 38 % H2O2 (Power whitening, WHITEsmile GmbH, Germany). The tip used was a 6-mm long Z-type glass tip (MZ8) of a 800 µm diameter. Average output power was set to 1.25 W, pulse duration 700 µs (S-mode), whilst the pulse repetition rate was 10 Hz. The results showed that the most susceptible teeth in terms of pulp temperature increase were the lateral maxillary incisors and the mandibular incisors. The mean temperature increase on these teeth was 1.06 and 1.00 °C, respectively, on 60 s Er,Cr:YSGG-supported bleaching.

Bonding strength of silorane-based composite to Er-YAG laser prepared dentin.

The aim of this study was to investigate the shear bond strength of two adhesive systems to laser-irradiated dentin compared with their shear bond strength to bur-cut dentin as well as to evaluate the influence of composition and type of dental materials on shear bond strength. Thirty-two dentin specimens prepared from human third molars were divided into two groups and conditioned either with an Er:YAG laser machine or with a carbide bur. Two different adhesive systems (Silorane System Adhesive and Single Bond) were evaluated in the present study. After light curing of the adhesives, a Teflon mold was placed over the ring with the dentin sample and filled with the composite resins Filtek Silorane and Filtek Z250 combined with the appropriate adhesive systems. This procedure resulted in 32 cylindrical specimens (3 mm in diameter, 4 mm in height) being bonded to the dentin. The specimens were stored for 24 h at 37 °C in water and then were thermocycled. Shear bond strength testing was conducted by means of a universal testing machine and failure patterns were analyzed under a stereomicroscope. Two specimens of each fracture failure mode were randomly selected for SEM evaluation. Filtek Silorane present no statistically significant difference in shear bond strength compared with Filtek Z250, regardless of dentin treatment (p > 0.05). Additionally, the self-etching Silorane Adhesive System exhibited as good adhesive values as etch-and-rinse Single Bond, independently on dentinal substrate (p > 0.05). Specimens prepared by Er:YAG laser appear as receptive to adhesive procedures as conventional carbide bur-cut specimens (p > 0.05).

The evaluation of various restoration techniques on internal adaptation of composites in class v cavities.

Aim. The aim of this study was to evaluate the effect of different restoration techniques on the formation of internal microgaps between materials and dentin in class V restorations. Materials and Methods. Twenty-five extracted human premolars were prepared with standardized class V cavity outlines (3 mm × 2 mm × 2 mm). The cavities were randomly divided into 5 groups of 10 cavities each and restored according to manufacturer's instructions: Group 1: preheating (55°C) conventional composite (Filtek Z250), Group 2: flowable composite (Filtek Flow), Group 3: Filtek Flow + Filtek Z250 light-cured separately, Group 4: Filtek Flow + Filtek Z250 light-cured simultaneously, and Group 5 (control): Filtek Z250 at room temperature (23°C). The specimens were then thermocycled and cross-sectioned through the center of the restoration. Subsequently, impressions were taken, and epoxy resin replicas were made. The internal adaptation of the materials to the axial wall was analyzed under SEM. Results. The preheated Filtek Z250 (Group 1) showed better internal adaptation than the room temperature groups (P < 0.05). The combination of Filtek Flow with Filtek Z250 which was light-cured separately (Group 3) exhibited better internal adaptation than control group (P < 0.05). Conclusion. Different restoration techniques exhibit different behavior regarding internal adaptation to dentin after photopolymerization.

Effects of a new antibacterial adhesive on the repair capacity of the pulp-dentine complex in infected teeth.

AIM: To evaluate the effects of a self-etching/priming adhesive system, containing the antibacterial monomer 12-methacryloyloxy-dodecylpyridinium bromide (MDPB), on the repair capacity of the pulp-dentine complex in infected cavities in dog's teeth. METHODOLOGY: Class V cavities with a residual dentine thickness ranging from 0.3-0.8 mm were prepared on the buccal surface of permanent teeth in four dogs. Pulpal exposures were performed in half of the cavities. Millipore filters that had been incubated for 3 h in a 10(5) milky suspension of a-streptococci were placed in the cavities, which were then filled temporarily. After 24 h, the filters were removed and both the exposed and non-exposed cavities were washed with sterile saline and assigned to four groups which were treated with either the experimental antibacterial adhesive system, or Clearfil SE bond, Dycal and Teflon discs. Stereotype connective tissue reactions (inflammatory cell response and/or tissue necrosis) and pulp-specific reparative tissue responses (reduction of odontoblasts and tertiary dentine formation) were assessed at post-operative periods of 4 and 8 weeks. RESULTS: Neither severe inflammation nor tissue necrosis was observed, either in the dentinal cavities or pulpal exposures treated with the self-etch adhesive containing MDPB. Rates of tertiary dentine formation in infected dentinal cavities treated with this system were comparable with those observed after dentine treatment with the Ca(OH)2-based material. Dentinal bridging was not seen in pulpal exposures treated with the experimental adhesive. CONCLUSIONS: The new antibacterial adhesive system maintained pulp vitality and primary odontoblastic function in infected nonexposed and exposed cavities but interfered with reparative dentine formation in infected pulpal exposures.

Pulpal responses following direct pulp capping of healthy dog teeth with dentine adhesive systems.

OBJECTIVE: The aim of the present study was to evaluate the pulpal responses following direct pulp capping of mechanically exposed teeth with new dentine adhesive systems, in the preclinical model of dog teeth. METHODS: Class V cavities (approximately 2.50 mm wide, 3.00 mm long, 1.5-2.0 mm deep) were prepared on the buccal surface of permanent maxillary and mandibulary molars, two rooted premolars, canines and third incisors. The cavities were assigned to five experimental groups, representing one control group treated with a Ca(OH)2-based material and four experimental groups where the adhesive systems Clearfil SE Bond, Prompt-L-Pop, Etch & Prime 3.0 and Single Bond were tested. The pulpal tissue responses to dentine adhesives were assessed at post-operative periods of 7, 21, 65 days. RESULTS: Variable responses were recorded, which were characterized by moderate to severe inflammatory reactions, progressive extension of tissue necrosis with time and total absence of continuous hard tissue bridge formation after pulp capping with each of the four adhesive systems. Application of a Ca(OH)2-based material was characterized by inflammatory cell infiltration, limited tissue necrosis as well as partial to complete hard tissue bridging. CONCLUSIONS: It seems evident that application of dentine adhesive systems in direct contact with the mechanically exposed pulp of healthy dog teeth cannot lead to acceptable repair of the dentine-pulp complex e.g. wound healing with tertiary dentine bridge formation.

In vivo evaluation of microleakage from composites with new dentine adhesives.

The purpose of this study was to investigate microleakage in V class composite restorations with total etch versus self-etching adhesives. Experiments were conducted in vivo and were also evaluated interfacial micromorphology. Forty class V cavities were prepared on the buccal surfaces of teeth in three healthy dogs. The cavities were randomly assigned into five groups of eight teeth and restored with one of the following adhesive systems: Etch and Prime 3.0/Definite flow/Definite, Prompt L-pop/Filtek flow/P-60, Admira bond/Admira Flow /Admira, Bond 1/Flow it/Alert, Stae/Wave/Glacier. After 60 days the animals were killed and the teeth were extracted. The teeth were then immersed in a solution of 0.5% basic fuchsin dye for 24 h, sectioned and scored for microleakage. Features of the tooth/restoration interfaces were also examined using Scanning electron microscopy. Student-Newman-Keuls and one-way anova revealed significance differences among the groups for overall wall scores (P < 0.05). The total-etch adhesives revealed significantly less microleakage scores than the self-etching adhesive systems tested. Wilcoxon Signed Ranks Test revealed significant differences between the occlusal and gingival microleakage scores for each adhesive restorative system, with the exception of Admira (P < 0.05).