A modified approach for vestibuloplasty in severely resorbed mandible using an implant-retained postoperative stent: a case report

Background. Severely resorbed mandibles often present a short band of keratinized tissue associated with a shallow vestibule. As a result, prominent muscle insertions are present, especially in the mental region of the mandible. This case report describes the deepening of the vestibular sulcus in an atrophic mandible by combining free gingival grafts harvested from the palate and a postoperative acrylic resin stent screwed on osseointegrated implants placed at the anterior region of the mandible.Study design. During the second-stage surgery, a split-thickness labial flap was reflected and apically sutured onto the periosteum. Two free gingival grafts were obtained and then sutured at this recipient site. A previously custom-made acrylic stent was then screwed onto the most distally positioned implants. To document the procedure's stability over time, a metal ball was placed in the most apical part of the vestibule and standardized cephalometric radiographs were taken before and 6 months after the procedure. Linear measurements of vestibular depths over the observation time were realized using specific software for radiographic analysis.Results. The proposed technique augmented the band of attached masticatory mucosa, deepened the vestibule and prevented the muscle reinsertion. The difference between the 2 measurements of vestibular depths was 9.39 mm (initial 20.88 mm, final 11.49 mm) after a 6-month postoperative period.Conclusion. The technique, in combination with palatal mucosal graft and use of a postoperative stent, decreased the pull of mentalis muscle and provided a peri-implantally stable soft tissue around implants. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 106: e7-e14)

ESTUDO da RETENÇÃO ENTRE RESINA ACRÍLICA PARA BASE DE DENTADURA E DENTES DE RESINA ACRÍLICA

Foi avaliada a resistência de união entre dentes e base de dentadura, ambos de resina acrílica. Os dentes foram incluídos em blocos cilíndricos de resina e, posteriormente, torneados, para se obterem cilindros de 5mm de diâmetro. Sobre a extremidade do dente, era adaptado um padrão de cera de mesmo diâmetro, que, após inclusão na mufla, era substituído por resina acrílica termicamente ativada pelo método de processamento convencional de base de dentadura. Como variáveis, usaram-se duas marcas de dentes, duas fases de inclusão (plástica e borrachóide) e aplicação ou não de detergente e monômero sobre os dentes. Os corpos-de-prova, antes dos ensaios de ruptura por tração, foram armazenados em água destilada, a 37ºC, por 2 semanas. Os resultados mostraram que: marca de dente e fase de condensação não influíram nos resultados; somente o uso de detergente ou de monômero aumenta a retentividade e o seu uso conjunto apresenta efeito acumulativo.

Alteration of blue pigment in artificial iris in ocular prosthesis: Effect of paint, drying method and artificial aging

The artificial iris is the structure responsible for the dissimulation and aesthetics of ocular prosthesis. The objective of the present study was to evaluate the color stability of artificial iris of microwaveable polymerized ocular prosthesis, as a function of paint type, drying method and accelerated aging. A total of 40 discs of microwaveable polymerized acrylic resin were fabricated, and divided according to the blue paint type ( n = 5): hydrosoluble acrylic, nitrocellulose automotive, hydrosoluble gouache and oil paints. Paints where dried either at natural or at infrared light bulb method. Each specimen was constituted of one disc in colorless acrylic resin and another colored with a basic sclera pigment. Painting was performed in one surface of one of the discs. The specimens were submitted to an artificial aging chamber under ultraviolet light, during 1008 h. A reflective spectrophotometer was used to evaluate color changes. Data were evaluated by 3-way repeated-measures ANOVA and the Tukey HSD test (alpha = 0.05). All paints suffered color alteration. The oil paint presented the highest color resistance to artificial aging regardless of drying method. (C) 2010 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

TMJ Vibrations in Asymptomatic Patients Using Old and New Complete Dentures

Purpose: The aim of this study was to assess the presence of temporomandibular joint (TMJ) noises in subjects with severe bone resorption, who have worn the same complete dentures for over 10 years, and 5 months after treatment with increments of acrylic resin on the occlusal surface after having new dentures in place.Methods: After applying the research diagnostic criteria (RDC)/temporomandibular disorder (TMD) questionnaire, 20 asymptomatic subjects were assessed before and 5 months after the new dentures were put in place. Joint vibrations were assessed by the Sono Pak program by selecting the vibrations that occurred during the opening and closing cycle.Results: The means of the results revealed a nonnormal distribution and were submitted to Kruskal-Wallis statistical analysis (p < 0.05). The vibration means were of low intensity (<= 9.96 Hz). After rehabilitation, there was a reduction in the vibrations (<= 5.2 Hz) statistically significant only at the end of mouth opening with the old dentures when compared with the other cycles.Conclusion: The intensity and number of occurrences of joint vibrations were reduced after 5 months of wearing new dentures.

Resistência de união entre dentes artificiais e resinas acrílicas para base protética

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of water storage and heat treatment on the cytotoxicity of soft liners

Objective: To evaluate the effect of water storage time on the cytotoxicity of soft liners.Methods: Sample discs of soft liners Dentusoft, Dentuflex, Trusoft, Ufi-Gel-P and denture base acrylic resin Lucitone-550 were prepared and divided into four groups: GN: No treatment, G24: Stored in water at 37 degrees C for 24 h; G48: Stored in water at 37 degrees C for 48 h, GHW: Immersed in water at 55 degrees C for 10 min. To analyse the cytotoxic effect, three samples of each group were placed in tubes with Dubelcco's Modified Eagle Mediums and incubated at 37 degrees C for 24 h. During this period, the toxic substances were leached to the culture medium. The cytotoxicity was analysed quantitatively by the incorporation of radioactivity H-3-thymidine checking the number of viable cells (synthesis of DNA). The data were statistically analysed using two-way ANOVA and Tukey's honestly significant difference tests (alpha = 0.05).Results: Treatments did not reduce the cytotoxicity effect of the soft liners (p > 0.05). It was found that Ufi-Gel-P had a non-cytotoxic effect, Trusoft had a slightly cytotoxic effect, Dentuflex had a moderated cytotoxic effect, Dentusoft alternated between slightly and non-cytotoxic effect, and Lucitone-550 had non-cytotoxic effect when stored in water for 48 h.Conclusion: The effect of water storage and the heat treatment did not reduce the cytotoxicity of the soft liners.

Evaluation of the occlusion vertical dimension of complete dentures after microwave disinfection

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of surface treatments on the flexural strength of denture base repair

Objective: The purpose of this study was to evaluate the flexural strength of repairs made with autopolymerising acrylic resin after different treatments of joint surfaces.Material and Methods: Fifty rectangular specimens were made with heat-polymerised acrylic resin and 40 were repaired with autopolymerising acrylic resin following joint surface treatments: group 1 (intact specimens), group 2 (chemical treatment: wetting with methyl-methacrylate for 180 s), group 3 (abraded with silicon carbide paper), group 4 (abraded and wetting with methyl-methacrylate for 180 s) and group 5 (without surface treatment). The flexural strength was measured by a three-point bending test using a universal testing machine with a 100 Kgf load cell in the centre of repair at 5 mm/min cross-head speed. All data were analysed using one-way ANOVA and Tukey HSD test for multiple comparisons (p < 0.05).Results: Among repaired specimens, groups 2 and 4 had 66.53 +/- 3.4 and 69.38 +/- 1.8 MPa mean values and were similar. These groups had superior flexural strength than groups 3 and 5 that were similar and had 54.11 +/- 3.4 and 51.24 +/- 2.8 MPa mean values, respectively. Group 1 had a mean value of 108.30 +/- 2.8 MPa being the highest result.Conclusion: It can be concluded that the treatment of the joint surfaces with methyl-methacrylate increases the flexural strength of denture base repairs, although the strength is still lower than that observed for the intact denture base resin. Abrasion with sandpaper was not able to influence the flexural strength of repaired denture bases.

Disinfection of Bovine Enamel by Microwave Irradiation: Effect on the Surface Microhardness and Demineralization/Remineralization Processes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of microwave disinfection on the surface roughness of three denture base resins after tooth brushing

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

IMPROVEMENT TO THE MARGINAL COPING FIT of COMMERCIALLY PURE TITANIUM CAST IN PHOSPHATE-BONDED INVESTMENT BY USING A SIMPLE PATTERN COATING TECHNIQUE

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Customized fiber glass posts. Fatigue and fracture resistance

Purpose: To evaluate the root fracture strength of human single-rooted premolars restored with customized fiberglass post-core systems after fatigue simulation. Methods: 40 human premolars had their crowns cut and the root length was standardized to 13 mm. The teeth were endodontically treated and embedded in acrylic resin. The specimens were distributed into four groups (n=10) according to the restorative material used: prefabricated fiber post (PFP), PFP+accessory fiber posts (PFPa), PFP+unidirectional fiberglass (PFPf), and unidirectional fiberglass customized post (CP). All posts were luted using resin cement and the cores were built up with a resin composite. The samples were stored for 24 hours at 37 degrees C and 100% relative humidity and then submitted to mechanical cycling. The specimens were then compressive-loaded in a universal testing machine at a crosshead speed of 0.5 mm/minute until fracture. The failure patterns were analyzed and classified. Data was submitted to one-way ANOVA and Tukey's test (alpha= 0.05). Results: The mean values of maximum load (N) were: PFP - 811.4 +/- 124.3; PFPa - 729.2 +/- 157.2; PFPf - 747.5 +/- 204.7; CP - 762.4 +/- 110. Statistical differences were not observed among the groups. All groups showed favorable restorable failures. Fiberglass customized post did not show improved fracture resistance or differences in failure patterns when compared to prefabricated glass fiber posts. (Am J Dent 2012;25:35-38).

Effects of chlorhexidine and sodium hypochlorite on the microhardness of root canal dentin

Objective. The purpose of this study was to evaluate the effects of endodontic irrigants on the microhardness of root canal dentin.Study design. Thirty extracted single-rooted human teeth were used. The crowns were sectioned at the cementoenamel junction. Each root was transversely sectioned into cervical, middle, and apical segments, resulting in 90 specimens. The 3 sections of each root were separately mounted in an individual silicon device with acrylic resin. The specimens were randomly divided into the following 3 groups (n = 30), according to the irrigant solution used: (1) group 1, control (saline solution); (2) group 2, 2% chlorhexidine gluconate solution; and (3) group 3, 1% sodium hypochlorite (NaOCl). After 15 minutes of irrigation, dentin microhardness was measured on each section at 500 mu m and 1000 mu m from the pulp-dentin interface with a Vickers diamond microhardness tester in Vickers hardness number (VHN).Results. Data obtained were analyzed using analysis of variance and the Tukey test (5%). Specimens irrigated with 2% chlorhexidine (group 2) or 1% NaOCl (group 3) presented lower values of dentin microhardness, with significant difference in relation to the control group (P < .05).Conclusion. It could be concluded that chlorhexidine and NaOCl solutions significantly reduced the microhardness of root canal dentin at 500 mu m and 1000 mu m from the pulp-dentin interface.

Photodynamic inactivation of Staphylococcus aureus and Escherichia coli biofilms by malachite green and phenothiazine dyes: An in vitro study

Objectives: The organization of biofilms in the oral cavity gives them added resistance to antimicrobial agents. The action of phenothiazinic photosensitizers on oral biofilms has already been reported. However, the action of the malachite green photosensitizer upon biofilm-organized microorganisms has not been described. The objective of the present work was to compare the action of malachite green with the phenothiazinic photosensitizers (methylene blue and toluidine blue) on Staphylococcus aureus and Escherichia coli biofilms.Methods: The biofilms were grown on sample pieces of acrylic resin and subjected to photodynamic therapy using a 660-nm diode laser and photosensitizer concentrations ranging from 37.5 to 3000 mu M. After photodynamic therapy, cells from the biofilms were dispersed in a homogenizer and cultured in Brain Heart Infusion broth for quantification of colony-forming units per experimental protocol. For each tested microorganism, two control groups were maintained: one exposed to the laser radiation without the photosensitizer (L+PS-) and other treated with the photosensitizer without exposure to the red laser light (L-PS+). The results were subjected to descriptive statistical analysis.Results: The best results for S. aureus and E. coli biofilms were obtained with photosensitizer concentrations of approximately 300 mu M methylene blue, with microbial reductions of 0.8-1.0 log(10); 150 mu M toluidine blue, with microbial reductions of 0.9-1.0 log(10); and 3000 mu M malachite green, with microbial reductions of 1.6-4.0 log(10).Conclusion: Greater microbial reduction was achieved with the malachite green photosensitizer when used at higher concentrations than those employed for the phenothiazinic dyes. (C) 2011 Elsevier Ltd. All rights reserved.

Correlation between factors associated with the removable partial dentures use and Candida spp. in saliva

Objectives: To correlate the presence and number of Candida spp. in the saliva of wearers of removable partial dentures retained with precision attachments with the proportion of metal/acrylic resin present in the dentures. Methods: Saliva samples from 40 removable partial denture wearers (test) and one paired sample of individuals, non- wearers of any type of removable denture (control) were collected, seeded, and the colony forming units of Candida counted and identified. The metal/acrylic resin proportion of each denture was quantified, using silicone plates pressed over each denture. Results: Candida spp. was found in the saliva of 80% of the individuals in the test group and 65% of the control, with C. albicans being themost prevalent species. The test group presented with the highest number of colony forming units of Candida per ml of saliva, and there wasweak correlation between this number and the metal and resin area of the denture (Pearson's coefficient of correlation). Greater prevalence and a higher number of colony forming units of Candida per ml of saliva occurred in removable partial denture wearers ( p = 0.04) with a weak positive correlation between the metal and resin area and the number of colony forming units of Candida per ml of saliva. However, this correlation was more significant for the area of resin. Correlation between factors associated with the removable partial dentures use and Candida spp. in saliva