Evaluation of the sealing capability and morphological fit of prefabricated dowels and fiber-reinforced composite resin: An in vitro study.

STATEMENT OF PROBLEM: Prefabricated dowels do not always provide intraradicular sealing in the root canal dentin, and the lack of sealing predisposes the dowel to adhesive failure and debonding. It is unclear if fiber-reinforced composite resin dowels provide better sealing. PURPOSE: The purpose of this in vitro study was to evaluate the intraradicular sealing and morphological fit of prefabricated dowels and fiber-reinforced composite resin dowels in root canal dentin. The thickness of the resin cement layer and push-out bond strength were determined to assess their effects on the sealing of the dowels. MATERIAL AND METHODS: A total of 50 permanent maxillary central incisors were endodontically treated and divided into 2 subgroups (n=25). In one group, prefabricated dowels were cemented; in the second group, fiber-reinforced composite resin dowels were placed. The thickness of the resin cement layer was assessed in 3 different locations: coronal, middle, and apical of the root canal dentin with fluorescence confocal laser microscopy. The push-out bond strength was then determined, and intraradicular sealing observed by using scanning electron microscopy. RESULTS: Fiber-reinforced composite resin dowels showed a closer intraradicular fit and seal in the root canal dentin, and the morphology of the apical portion of the fiber-reinforced composite resin dowels showed a sealing area with the gutta percha in the apical portion. The mean thickness of the resin cement layer was significantly reduced for the fiber-reinforced composite resin dowels compared with the prefabricated dowels (P<.05) in the cervical area (197.0 µm versus 311.0 µm) and in the apical portion of the root canal (57.3 µm versus 131.6 µm). The mean push-out strength was higher for the fiber-reinforced composite resin dowels (22.98 N/mm2) than that for the prefabricated dowels (16.49 N/mm2) (P<.05). CONCLUSIONS: The morphological fit of fiber-reinforced composite resin dowels provides better intraradicular sealing in the cervical and apical portions, reducing the resin cement thickness. The increased push-out strength can therefore be assumed to result from increased frictional retention compared with prefabricated dowels.

Does microwave and hydrogen peroxide disinfection reduce Candida albicans biofilm on polymethyl methacrylate denture surfaces?

STATEMENT OF PROBLEM: Whether the disinfection of polymethyl methacrylate (PMMA) dentures eliminates Candida albicans biofilm is unclear. PURPOSE: The purpose of this in vitro study was to determine the antimicrobial effect of immersion in hydrogen peroxide (H2O2) and subsequent application of microwaves on the formation of C albicans biofilm on the surface of polished and unpolished PMMA disks. MATERIAL AND METHODS: Polished and unpolished PMMA disks (n=40) were mounted in a Center for Disease Control (CDC) biofilm reactor by adding yeast-dextrose-peptone (YPD) broth inoculated with C albicans in a cell suspension for 24 hours. After this period, the PMMA disks (n=8) were disinfected with 5 different solutions: saline solution, 1% sodium hypochlorite (NaOCl), H2O2, H2O2 microwaved at 650 W for 3 minutes (H2O2/µw), and distilled water microwaved at 650 W for 3 minutes (H2O/µw). On the polished and unpolished surface of each disk, arbitrary fluorescence units (AFU) were quantified with the live/dead bacterial viability kit (Invitrogen) by using confocal laser scanning microscopy (CLSM) to evaluate 10 different areas of each surface; these were counted as the colony-forming units (CFUs). The mean values were compared by using the Mann-Whitney U test (α=.05). RESULTS: Polished surfaces disinfected with H2O2/µw obtained the lowest viable cells (9.76 AFU) and nonviable cells (12.46 AFU) compared with H2O/µw and H2O2. In the unpolished surface the lowest mean values of viable cells (14.64 AFU) and nonviable cells (12.46 AFU) were obtained for the PMMA disks disinfected with H2O/µw compared with H2O2/µw and H2O2. Both polished and unpolished disks showed significant difference (P<.05) compared with the group of PMMA disks immersed in saline solution. No CFUs were detected in the polished or unpolished PMMA disks immersed in H2O2/µw or in NaOCl. CONCLUSIONS: H2O2 alone did not eliminate the formation of the biofilm of C albicans; however, in combination with the use of the microwave at 650 W for 3 minutes, the biofilm formation of C albicans on polished surfaces was reduced. The number of AFUs of viable-nonviable cells and CFUs depended on whether the surfaces are polished or unpolished.

Effects of drug abuse and mental disorders on oral health: A case report.

Substance use disorders, related to mental health issues can lead to oral pathologies. The purpose of this case report was to identify the oral conditions and manifestations in a 28-year-old male narco-dependent schizophrenic who smoked tobacco and marijuana. In intra-oral clinical exploration, poor oral hygiene, excessive tartar formation and dental plaque were observed, and the diagnosis of severe chronic periodontitis was established. The choice of a treatment plan in such patients is complex because the consequences of an invasive treatment can aggravate the psychological state and emotional stability leading to a negative effect on behaviour and mental health due to edentulism. The effects of excessive drug consumption related to schizophrenia can cause poor oral hygiene habits leading to oral pathologies and the loss of teeth.

Postextraction Alveolar Preservation and Use of the Crown of the Extracted Tooth as a Temporary Restoration.

Ranging from the extraction of teeth from anterior sector commitment to the loss of bone and soft tissues, alveolar preservation is a regenerative technique that employs biomaterials that induce the preservation of bone tissue and minimize resorption. Placement of provisional restorations at the defect site maintains the stability of the soft tissues and aesthetics at which the definitive restoration is found. The objective of this clinical case was alveolar preservation postextraction of the anterior tooth that presented a coronal fracture, placing the clinical crown of the extracted tooth as the provisional restoration to maintain stability and to avoid soft tissue collapse and compromise to an aesthetic area.