Delayed replantation of rat teeth after use of reconstituted powdered milk as a storage medium

Minimal extraoral dry storage period and moist storage for the avulsed tooth are identified as key steps for the treatment protocol of tooth replantation. Among the possible moist storage media, bovine milk has stood out because of its capacity of preserving the integrity of the periodontal ligament (PDL) fibers. This condition has attracted the attention to investigate the use of powdered milk, which is one of the presentation forms of bovine milk, as a feasible storage medium in cases of delayed tooth replantation. The aim of this study was to evaluate the healing process after delayed replantation of rat teeth stored in reconstituted powdered milk and long shelf-life (ultra high temperature) whole milk. Forty maxillary right rat incisors were assigned to four groups (n = 10): group I - the teeth were extracted and immediately replanted into theirs sockets; group II - the teeth were stored for 60 min in 200 ml of freshly reconstituted powdered milk; group III - the teeth were stored for 60 min in 200 ml of long shelf-life whole milk; group IV - the teeth were kept dry for the same time. All procedures were performed at room temperature. Next, the root canals of teeth in groups II, III, and IV were instrumented, filled with a calcium hydroxide-based paste, and replanted into their sockets. All animals received systemic antibiotic therapy and were killed by anesthetic overdose 60 days after replantation. The pieces containing the replanted teeth were removed, fixed, decalcified, and paraffin-embedded. Semi-serial 6-mu m-thick sections were obtained and stained with hematoxylin and eosin for histomorphological analysis. There was statistically significant difference (P < 0.05) between groups I and IV regarding the presence of replacement resorption and PDL remnants on root surface. The powdered milk and long shelf-life whole milk presented similar results to each other and may be indicated as storage media for avulsed teeth.

Effect of Chemical Disinfection and Accelerated Aging on Color Stability of Maxillofacial Silicone with Opacifiers

Purpose: The purpose of this study was to evaluate the color stability of MDX4-4210 maxillofacial elastomer with opacifier addition submitted to chemical disinfection and accelerated aging.Materials and Methods: Ninety specimens were obtained from Silastic MDX4-4210 silicone. The specimens were divided into three groups (n = 30): Group I: colorless, Group II: barium sulfate opacifier, Group III: titanium dioxide opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was conducted three times a week for 2 months. Afterward, the specimens were submitted to different periods of accelerated aging. Color evaluation was carried out after 60 days (disinfection period) and after 252, 504, and 1008 hours of accelerated aging, using a reflection spectrophotometer. Color alterations were calculated by the CIE L*a*b* system. Data were analyzed by three-way ANOVA and Tukey test (alpha = 0.05).Results: Group II exhibited the lowest color change, whereas Group III the highest (p < 0.05), regardless of the chemical disinfection and accelerated aging periods.Conclusion: Opacifier addition, chemical disinfection, and accelerated aging procedures affected the color stability of the maxillofacial silicone.

Comparative evaluation of the efficacy of occlusal splints fabricated in centric relation or maximum intercuspation in temporomandibular disorders patients

Fabrication of occlusal splints in centric relation for temporomandibular disorders (TMD) patients is arguable, since this position has been defined for asymptomatic stomatognathic system. Thus, maximum intercuspation might be employed in patients with occlusal stability, eliminating the need for interocclusal records. This study compared occlusal splints fabricated in centric relation and maximum intercuspation in muscle pain reduction of TMD patients. Twenty patients with TMD of myogenous origin and bruxism were divided into 2 groups treated with splints in maximum intercuspation (I) or centric relation (II). Clinical, electrognathographic and electromyographic examinations were performed before and 3 months after therapy. Data were analyzed by the Student's t test. Differences at 5% level of probability were considered statistically significant. There was a remarkable reduction in pain symptomatology, without statistically significant differences (p>0.05) between the groups. There was mandibular repositioning during therapy, as demonstrated by the change in occlusal contacts on the splints. Electrognathographic examination demonstrated a significant increase in maximum left lateral movement for group I and right lateral movement for group II (p<0.05). There were no significant differences (p>0.05) in the electromyographic activities at rest after utilization of both splints. In conclusion, both occlusal splints were effective for pain control and presented similar action. The results suggest that maximum intercuspation may be used for fabrication of occlusal splints in patients with occlusal stability without large discrepancies between centric relation and maximum intercuspation. Moreover, this technique is simpler and less expensive.

Biomimetic calcium phosphate coating on Ti-7.5Mo alloy for dental application

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

Effect of Vertical Misfit on Screw Joint Stability of Implant-Supported Crowns

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

Color stability of maxillofacial silicone with nanoparticle pigment and opacifier submitted to disinfection and artificial aging

The purpose of this study was to evaluate the color stability of a maxillofacial elastomer with the addition of a nanoparticle pigment and/or an opacifier submitted to chemical disinfection and artificial aging. Specimens were divided into four groups (n = 30): group I: silicone without pigment or opacifier, group II: ceramic powder pigment, group III: Barium sulfate (BaSO(4)) opacifier, and group IV: ceramic powder and BaSO(4) opacifier. Specimens of each group (n = 10) were disinfected with effervescent tablets, neutral soap, or 4% chlorhexidine gluconate. Disinfection was done three times a week during two months. Afterward, specimens were submitted to different periods of artificial aging. Color evaluation was initially done, after 60 days (disinfection period) and after 252, 504, and 1008 h of artificial aging with aid of a reflection spectrophotometer. Data were analyzed by three-way ANOVA and Tukey test (alpha = 0.05). The isolated factor disinfection did not statistically influence the values of color stability among groups. The association between pigment and BaSO(4) opacifier (GIV) was more stable in relationship to color change (Delta E). All values of Delta E obtained, independent of the disinfectant and the period of artificial aging, were considered acceptable in agreement with the norms presented in literature. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.3625401]

Avaliação ortopantomográfica das angulações mesiodistais de caninos, pré-molares e molares inferiores com e sem a presença dos terceiros molares

OBJETIVOS: comparar os valores médios normais das angulações mesiodistais dentárias, propostos por Ursi, em 1989, com as angulações mesiodistais de caninos, pré-molares e molares inferiores em indivíduos com e sem a presença dos terceiros molares inferiores e idades entre 18 e 25 anos. Além disso, foram comparados os valores das angulações mesiodistais desses dentes nessas duas situações. MÉTODOS: foram utilizadas 40 radiografias ortopantomográficas de indivíduos, de ambos os gêneros, que não receberam tratamento ortodôntico, divididos em dois grupos: Grupo I, constituído por 20 radiografias que não apresentavam os terceiros molares inferiores; e Grupo II, formado por 20 radiografias com os terceiros molares inferiores presentes. RESULTADOS E CONCLUSÕES: a análise dos resultados e a análise estatística permitiram concluir que ambos os grupos exibiram pré-molares e molares inferiores mais angulados em sentido mesial, quando comparados à oclusão normal. Por outro lado, a angulação mesiodistal de caninos inferiores mostrou-se semelhante àquela apresentada em casos de oclusão normal. Os dois grupos, quando comparados entre si, exibiram semelhantes valores angulares dos caninos, pré-molares e molares inferiores, de modo que a presença dos terceiros molares não exerceu influência sobre essas angulações mesiodistais dentárias.

Bone healing in critical-size defects treated with either bone graft, membrane, or a combination of both materials: a histological and histometric study in rat tibiae

Objectives: The aim of the present investigation was to histologically analyze the effect of using lyophilized bovine bone (GenOx (R) organic matrix) with (or without) guided tissue regeneration (using a decalcified cortical osseous membrane [GenDerm (R)]) on bone healing in surgically created critical-size defects created in rat tibia.Material and methods: Surgical critical-size bone defects were created in 64 animals that were randomly divided into four groups: group I (control); group II (defect filled with GenOx (R)); group III (defect covered by GenDerm (R)); group IV (defect filled with GenOx (R) and covered by GenDerm (R)). Animals were killed at 30 or 90 days post-surgery. The specimens were embedded in paraffin, serially cut, and stained with hematoxylin and eosin for analysis under light microscopy. The formation of new bone in the cortical area of the defect was histomorphometrically evaluated.Results: All experimental groups demonstrated superior bone healing compared with the control group. However, group IV samples showed evidence of more advanced healing at both 30 and 90 days post-surgery as compared with the other experimental groups.Conclusions: The bovine organic bone graft GenOx (R) associated with GenDerm (R) this produced the best treatment results in the case of critical-size defects in rat tibia.

Light-Emitting Diode Therapy in Chemotherapy-Induced Mucositis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of cyclosporin A on alveolar bone homeostasis in a rat periodontitis model

Objectives: the administration of cyclosporin A has been associated with significant bone loss and increased bone remodeling. The present investigation was designed to evaluate the effects of cyclosporin A on alveolar bone of rats subjected to experimental periodontitis, using serum, stereometric and radiographic analysis.Methods: Twenty-four rats were divided into one of the following groups with six animals each: group I, control rats; group II, in which the animals received a cotton ligature around the lower first molars; group III, in which the rats received a cotton ligature around the lower first molars and were treated with 10 mg/(kg body weight day) of cyclosporin A; group IV, in which the rats were treated with 10 mg/(kg body weight day) of cyclosporin A. At the end of experimental period, at 30 days, animals were killed and the serum calcium and alkaline phosphatase levels were measured in all groups. The distance from the alveolar bone crest to the cemento-enamel junction was measured radiographically for each mesial surface of the lower first molars of each rat. After histological processing, the stereological parameters: volume densities of multinucleated osteoclasts (V-o), alveolar bone (V-b), marrow (V-m), and relation of eroded surface/bone surface (Es/Bs) were assessed at the mesial region of the alveolar bone.Results: Significant decreases in serum calcium were observed in those groups that received cyclosporin A therapy. No significant changes in serum alkaline phosphatase were observed. The therapy with cyclosporin A combined with the ligature placement decreased the V-b and increased the V-o, V-m and Es/Bs at the mesial surface of lower first molars. on the other hand, the radiographic data showed that cyclosporin A therapy diminished the alveolar bone loss at the mesial surface of the lower first molars.Conclusions: Therefore, within the limits of this study, we suggest that cyclosporin A at immunosuppressive levels can bring about an imbalance in the alveolar bone homeostasis in rats. However, in the presence of inflammatory stimulation, the inhibition of the immune system by cyclosporin A may decrease the initial periodontal breakdown.

The influence of short-term diabetes mellitus and insulin therapy on alveolar bone loss in rats

Background: It is well known that the multiple direct and indirect consequences of hyperglycemia in diabetic individuals have been linked to a number of abnormal host effector mechanisms that could lead to an increased risk of developing periodontal disease.Objective: the aim of this study was to investigate the effect of short-term experimental diabetes and insulin therapy on the severity of alveolar bone loss in rats, and the effect of experimental periodontitis on glycemic control.Methods: Seventy-two male Wistar rats were divided into four groups: group I animals were submitted to dental ligature around lower right first molars (ligated); group II consisted of streptozotocin (STZ)-diabetic, ligated rats; group III represented STZ-diabetic, unligated rats; and group IV consisted of insulin-treated (6 U/day), STZ-diabetic, ligated rats. Blood glucose of all diabetic rats was monitored at regular intervals. Standardized digital radiographs were taken after killing at 7, 15 and 30 days to measure the amount of bone loss about the mesial root surface of the first molar tooth in each rat.Results: No significant (p < 0.05) changes in plasma glucose levels of insulin-treated diabetic rats were found among the different examinations after the beginning of insulin therapy. Rats from group II showed significantly greater increases in mean plasma glucose levels at 15 and 30 days after ligature placement compared with rats from group III (p < 0.05). Furthermore, in spite of the significant alveolar bone loss progression that was observed in groups I, II and IV (p < 0.00001; two-way ANOVA), no significant differences among these groups regarding the severity of bone loss (p = 0.77) and no significant interaction between treatment group and time (p = 0.81) were found.Conclusions: Within the limits of this study, it can be suggested that the severity of periodontal disease was not affected by short-term diabetes, and that experimental periodontitis increased blood glucose levels in uncontrolled diabetic rats.

An in vitro evaluation of apicoectomies and retropreparations using different methods

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

Histomorphometric analysis of the repair process of autogenous bone grafts fixed at rat calvaria with cyanoacrylate

Objective: The purpose of this study was to perform histological and histometric analyses of the repair process of autogenous bone grafts fixed at rat calvaria with ethyl-cyanoacrylate adhesive. Material and Methods: Thirty-two rats were divided into two groups (n=16), Group I - Control and Group II - Adhesive. Osteotomies were made at the right parietal bone for graft obtainment using a 4-mm-diameter trephine drill. Then, the bone segments were fixed with the adhesive in the parietal region of the opposite side to the donor site. After 10 and 30 days, 8 animals of each group were euthanized and the calvarias were laboratorially processed for obtaining hematoxylin and eosin-stained slides for histological and histometric analyses. Results: An intense inflammatory reaction was observed at the 10-day period. At 30 days, this reaction was less intense, despite the presence of adhesive at the recipient-site/graft interface. Graft incorporation to the recipient site was observed only at the control group, which maintained the highest graft size at 10 and 30 days. Conclusions: Although the fragment was stable, the presence of adhesive in Group II did not allow graft incorporation to the recipient site, determining a localized, discrete and persistent inflammatory reaction.

Maxillary complete denture movement during chewing in mandibular removable partial denture wearers

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

Effect of oral hygiene education and motivation on removable partial denture wearers: longitudinal study

The purpose of this study was to determine the effect of two different preventive oral hygiene education and motivation programmes on the plaque and gingival index, as well as denture hygiene of patients provided with removable partial denture (RPD) during a 12-month follow-up.A total of 53 partially edentulous patients were recruited for this study. The presence or absence of plaque and gingival bleeding by gentle probing was scored on all tooth surfaces at the preliminary visit. The plaque and gingival indexes were measured using the Loe index. Following treatment, the patients were randomly divided into three groups. In Control Group I, subjects were instructed to continue their personal oral hygiene routine. In Group II, participants were given verbal instructions and a self-educational manual on oral hygiene without illustrations. In Group III, oral hygiene guidance was delivered using a combination of verbal instructions and a self-teaching manual. To evaluate the effect of the different modes of instruction, the presence or absence of plaque and gingival bleeding was scored on all tooth surfaces (day zero examination) and re-examined 7, 15 and 30 days, 3, 6 and 12 months following RPD placement. The state of denture hygiene was evaluated 7, 15 and 30 days and 3, 6 and 12 months following rehabilitation. Parametric statistics was applied to dental plaque and gingival indexes. For accumulation of plaque and calculus on the RPD, non-parametric statistic was applied.The frequency of plaque found during the preliminary visit was higher than that found in the other periods. With regard to gingival index, significant difference was found between the preliminary visit examination and other periods. There was a significant difference in the plaque accumulation on the denture surface between groups I and III.The different methods of oral hygiene instruction used in this study indicate that the type of education was not of significant importance.