Finite-Element Analysis of Stress on Dental Implant Prosthesis

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

Wear resistance of experimental titanium alloys for dental applications

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

Infrared spectroscopy: a tool for determination of the degree of conversion in dental composites

Infrared spectroscopy is one of the most widely used techniques for measurement of conversion degree in dental composites. However, to obtain good quality spectra and quantitative analysis from spectral data, appropriate expertise and knowledge of the technique are mandatory. This paper presents important details to use infrared spectroscopy for determination of the conversion degree.

Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação clínica de pacientes submetidos à colocação de implantes zigomáticos pela técnica de Stella & Warner

This study aimed to evaluate patients who underwent placement of zygomatic implants technique by Stella & Warner, considering the survival of conventional and zygomatic implants, sinus health and level of patient satisfaction in relation to oral rehabilitation. We evaluated 28 patients where 14 had received conventional and zygomatic implants, being rehabilitated with implant-fixed dentures (group 1) and 14 were rehabilitated only with conventional implants and implant-fixed dentures (group 2). The study had four phases, represented by radiographic evaluation of implants (stage I), clinical evaluation (stage II), assessing the health of the maxillary sinus (stage III) and a questionnaire to measure satisfaction of rehabilitation with fixed prosthesis implant Total -backed (stage IV). Group 2 underwent only stage IV, while group 1 participated in all stages. Descriptive analysis and statistics were performed, using the t test for independent samples in the evaluation of phase IV. The results demonstrated that the technique of Stella & Warner proved effective, allowing a high survival rate of conventional implants and zygomatic (100%), considering a minimum follow-up of 15 months and maximum 53 months after prosthetic rehabilitation. There were no pathological changes in tissues periimplants conventional and zygomatic implants analyzed. Radiographic findings showed satisfactory levels bone implants in the oral rehabilitation with conventional zygomatic implants and a good positioning of the apex of the zygomatic implants over the zygomatic bone. The presence of the zygomatic implant did not cause sinus and the t test showed a satisfaction index lower in group 1 compared with group 2. The zygomatic implant placement technique by Stella & Warner proved to be a predictable technique with high survival rate in patients with atrophic jaws, necessitating long-term follow-up to confirm the initial findings of the study

Avaliação clínica e radiográfica das complicações técnicas em próteses sobre implantes

The evaluation criteria of the cases treated with dental implants are based on clinical and radiographic tests. In this context it is important to conduct research to determine prognosis of different types of prosthetic rehabilitation and determination of the main problems affecting this type of treatment. Thus, the objective of this study was to assess the prosthetic conditions of individuals rehabilitated with implant-supported prosthesis. In this cross-sectional study 153 patients were treated, accounting for a sample of 509 implants. The failures were observed by clinical and radiographic examination. The results showed that the fracture (0.2%) loss (0.4%) and loosening of the screws (3.3%) were failures are less frequent. The fracture structures as the resin (12.4%), porcelain (5.5%) and metallic (1.5%), loss of resin that covers the screw (23.8%) and loss of retention overdentures on implants (18.6%) had a higher occurrence. The failure of adaptation between the abutment and the implant (6.9%) and especially between the prosthesis and the abutment (25.4%) had a high prevalence and, when related to other parameters showed a significant association, particularly with the cemented prosthesis (OR = 6.79). It can be concluded that to minimize the appearance of failures, protocols must be observed from diagnosis to the settlement and control of prostheses on implants, particularly with respect to technical steps of the making of the prosthesis and care in radiographic evaluating the fit between their components

Assessment of genetic relationship between Klebsiella pneumoniae and Klebsiella oxytoca samples isolated from a dental office

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Assessment of genetic damage induced by dental bleaching agents on mouse lymphoma cells by single cell gel (comet) assay

Dental bleaching is a simple and conservative procedure for aesthetic restoration of vital discoloured teeth. However, dental bleaching agents may represent a hazard to human health, especially by causing DNA strand breaks. Genotoxicity tests form an important part of cancer research and risk assessment of potential carcinogens. In the current study, the genotoxic potential associated with exposure to dental bleaching agents was assessed by the single cell gel (comet) assay in vitro. Six commercial dental bleaching agents (Clarigel Gold - Dentsply; Whitespeed - Discus Dental; Nite White - Discus Dental; Magic Bleaching - Vigodent; Whiteness HP - FGM and Lase Peroxide - DMC) were exposed to mouse lymphoma cells in vitro. The results pointed out that all dental bleaching agents tested contributed to the DNA damage as depicted by the mean tail moment. Clear concentration-related effects were obtained for DNA damaging, being the strongest effect observed at the highest dose of the hydrogen peroxide (Whiteness HP and Lase Peroxide, at 35% concentration). on the contrary, Whitespeed (Discus Dental) induced the lowest level of DNA breakage. Taken together, these results suggest that dental bleaching agents may be a factor that increases the level of DNA damage as detected by the single cell gel (comet) assay.

Expression of cell cycle regulatory proteins in epithelial components of dental follicles

Dental follicle is a component of tooth germs, which remain adjacent to the crown of unerupted or impacted teeth. Under the influence of pathologic changes, however, dental follicles that possess reduced epithelium can proliferate into stratified squamous epithelium as far as originate dental cysts. In order to clarify the role of apoptosis and cellular proliferation herein, expression of p53 and PCNA was examined in epithelial components of dental follicles associated with impacted third molars by means of immunohistochemistry. A total of 40 cases was included in this study being 22 cases with reduced epithelium and 18 cases with stratified epithelium. Expression of p53 expression was weak or not detected in dental follicles with reduced and stratified squamous epithelium. By contrast, PCNA positive cells were evidenced in basal and supra basal layers of the stratified squamous epithelium and in reduced epithelium of dental follicles, but without any significant statistically differences between them (P > 0.05). In conclusion, these data suggest that dental follicles possess proliferative activity as depicted by PCNA-positive nuclei in some epithelial cells. However, the biological behavior of dental follicles during the late stage of dental eruptive process may not be associated with deregulation of death and/or cell proliferation.

Oral cavity evaluation and dental chart registration of coati (Nasua nasua) in captivity

The aims of this study were to develop a dental chart evaluate any oral cavity disease, develop gypsum models the dental arches, and to register the occlusions found in coatis (Nasua nasua) in captivity. Formulation of the dental chart was assisted by intraoral radiographs from the head of an adult coati cadaver of the same species with the following dental formula: I 3/3, C 1/1, P 4/3, M 2/2. Seven live coatis of the Nasua nasua species were evaluated. Five of the seven coatis presented with various dental abnormalities as follows: dental plaque (71.4 %), gingivitis (71.4 %), periodontitis (57.1 %), dental stain (42.9 %), dental abrasion (57.1 %), dental fracture (57.1 %), pulp exposure (42.9 %), malocclusion (5 7.1 %) and supernumerary teeth (14.2 %).

Strategies to improve fertility in Bos indicus postpubertal heifers and nonlactating cows submitted to fixed-time artificial insemination

Two experiments were designed to evaluate strategies to increase fertility of Bos indicus postpubertal heifers and nonlactating cows submitted to a fixed-time artificial insemination (TAI) protocol consisting of an intravaginal device containing 1.9 g of progesterone (CIDR) insertion + estradiol benzoate on Day 0, CIDR withdrawal + estradiol cypionate on Day 9, and TAI on Day 11. In Experiment 1, heifers (n = 1153) received a new or an 18-d previously used CIDR and, on Day 9, prostaglandin F(2 alpha) (PGF(2 alpha)) + 0, 200, or 300 IU equine chorionic gonadotropin (eCG). Heifers treated with a new CIDR had greater (least squares means +/- SEM) serum concentration of progesterone on Day 9 (3.06 +/- 0.09 ng/mL vs. 2.53 +/- 0.09 ng/mL; P < 0.05) and a smaller follicle at TAI (11.61 +/- 0.11 nim vs. 12.05 +/- 0.12 mm; P < 0.05). Heifers with smaller follicles at TAI had lesser serum progesterone, concentrations on Day 18 and reduced rates of ovulation, conception, and pregnancy (P < 0.05). Treatment with eCG improved (P < 0.05) follicle diameter at TAI (11.50 +/- 0.10 mm, 11.90 +/- 0.11 mm, and 12.00 +/- 0.10 mm, for 0, 100, and 200 IU, respectively), serum progesterone concentration on Day 18 (2.77 +/- 0.11 ng/mL, 3.81 +/- 0.11 ng/mL, and 4.87 +/- 0.11 ng/mL), and rates of ovulation (83.8%, 88.5%, and 94.3%) and pregnancy (41.3%, 47.0%, and 46.7%). In Experiment 2, nonlactating Nelore cows (n = 702) received PGF(2 alpha) treatment on Days 7 or 9 and, on Day 9, 0 or 300 IU cCG. Cows receiving PGF(2 alpha) on Day 7 had lesser serum progesterone concentrations on Day 9 (3.05 +/- 0.21 ng/mL vs. 4.58 +/- 0.21 ng/mL; P < 0.05), a larger follicle at TAI (11.54 +/- 0.21 mm vs. 10.84 +/- 0.21 mm; P < 0.05), and improved (P < 0.05) rates of ovulation (85.4% vs. 77.0%), conception (60.9% vs. 47.2%), and pregnancy (52.0% vs. 36.4%). Treatment with eCG improved (P < 0.05) serum progesterone concentration on Day 18 (3.24 +/- 0.14 ng/mL vs. 4.55 +/- 0.14 ng/mL) and the rates of ovulation (72.4% vs. 90.0%) and pregnancy (37.5% vs. 50.8%). In conclusion, giving PGF(2 alpha) earlier in the protocol in nonlactating cows and eCG treatment in postpubertal heifers and nonlactating cows improved fertility in response to a TAI (progesterone + estradiol) protocol. (C) 2009 Elsevier B.V. All rights reserved.

Fixed-time artificial insemination with estradiol and progesterone for Bos indicus cows II: Strategies and factors affecting fertility

In Experiments 1, 2, and 3, we evaluated the effects of temporary weaning (TW), equine chorionic gonadotropin (eCG), and follicle-stimulating hormone (FSH) treatments on results of it fixed-time artificial insemination (TAI) protocol in postpartum Bos indicus cows. In Experiment 1, treatment with 400 IU eCG or with TW for 48 h consistently improved pregnancy rates (PRs) at TAI, but, in Experiment 2, FSH treatment was less effective than eCG or TW. In Experiment 3, the inclusion of eCG treatment in cows subjected to TW did not improve PRs. We concluded that TW or 400 IU eCG should be included in the TAI protocol in postpartum Bos indicus cows to enhance fertility. In Experiment 4, we used records front heifers and cows treated with the proposed protocol during the 2006-2007 (n = 27,195) and 2007-2008 (n = 36,838) breeding seasons from multiple locations in Brazil to evaluate factors potentially affecting PRs. Overall PR at TAI was 49.6% (31,786 of 64,033). Pregnancy rate differed (P < 0.01) among farm within location (results ranging between 26.8% and 68.0%; P < 0.01), cow group within farm, by breed (Bos indicus, 48.3% [26,123 of 54,145]; Bos taurus, 61.7% [3652 of 5922]; and crossbred Bos indicus x Bos taurus, 50.7% [2011 of 3966]), category (nulliparous, 39.6% [2095 of 52901] suckled primiparous, 45.2% [3924 of 8677]; suckled multiparous, 51.8% [24,245 of 46,767]; and nonsuckled multiparous, 46.1% [1522 of 3299]), body condition score at TAI (<= 2.5 43.0% [3409 of 7923]; 3.0, 49.6% [18,958 of 38,229]; and >3.5, 52.7% [9419 of 17,881]). Days postpartum at beginning, of protocol did not affect PR (30 to 60 d, 47.6% [4228 of 8881]; 61 to 90 d, 51.7% 116,325 to 31,5721; and 91 to 150 d, 50.8% [7616 to 14,991]; P > 0.1). Pregnancy rate was also consistently affected (P < 0.01) by sire (results ranging from 7.2% to 77.3%) and artificial insemination technician (results ranging from 15.1% to 81.8%). (C) 2009 Elsevier B.V. All rights reserved.

Fertility-associated antigen on Nelore bull sperm and reproductive outcomes following first-service fixed-time AT of Nelore cows and heifers

The objective was to determine whether the presence of fertility-associated antigen (FAA) on sperm collected from Nelore (Bos indicus) bulls can be used to assess potential fertility of sperm for use at first-service fixed-time AI (TAI). Six Nelore bulls were selected based on FAA status (FAA-negative: N = 3; FAA-positive: N = 3) and the ability to produce neat semen with >= 70% morphologically normal sperm and 60% estimated progressive motility before cryopmservation. In Experiment 1, suckled multiparous Nelore cows (N = 835) were evaluated for body condition score (BCS) and received an intravaginal progesterone device (CIDR) and 2.0 mg of estradiol benzoate (Day 0). on Day 9 the CIDR was removed, 12.5 mg of PGF(2 alpha) and 0.5 mg of estradiol cypionate were administered, and calves were removed for 48 h. All cows received TAI on Day II (48 h after CIDR removal). Pregnancy per TAI (P/TAI) was not different between FAA-positive and FAA-negative bulls (41.5% vs. 39.3%, respectively). There was an effect of AI technician on P/TAI (36.0% vs. 43.9%; P < 0.05) and BCS tended to affect P/TAI (P = 0.09), as cows with BCS >= 2.75 were 1.4 times more likely to become pregnant compared with cows with BCS < 2.75. In Experiment 2, nulliparous Nelore heifers (N = 617) were evaluated for BCS and received a CIDR and estradiol benzoate (2.0 mg) on Day 0. on Day 7, all heifers received PGF(2 alpha) (12.5 mg). on Day 9, CIDR inserts were removed and all heifers received estradiol cypionate (0.6 mg) and 200 IU eCG. All heifers received TAI on Day 11 (48 h after CIDR removal). Pregnancy/TAI was different (P = 0.04) between FAA-positive and FAA-negative bulls (33.7% vs. 40.7%, respectively). Presence of FAA on sperm was unsuccessful in assessing the potential fertility of sperm for use in TAI. (C) 2012 Elsevier B.V. All rights reserved.

Fixed-time artificial insemination with estradiol and progesterone for Bos indicus cows I: Basis for development of protocols

Five experiments were conducted on commercial farms in Brazil aiming to develop a fixed-time artificial insemination (TAI) protocol that achieved pregnancy rates between 40% and 55% in Bos indicus cows. These studies resulted in the development of the following protocol: insertion of all intravaginal device containing 1.9 g of progesterone (CIDR) plus 2.0 mg im estradiol benzoate on Day 0; 12.5 mg im dinoprost tromethamine on Day 7 in cycling cows or oil Day 9 in anestrous cows; CIDR withdrawal plus 0.5 mg im estradiol cypionate plus temporary calf removal on Day 9; TAI (48 h after CIDR withdrawal) plus reuniting of calves with their dams on Day 11. Reduced dose of prostaglandin F(2 alpha) (PGF(2 alpha): 12.5 mg im dinoprost tromethamine) effectively caused luteolysis. In cycling cows, fertility was greater when the treatment with PGF(2 alpha) was administered on Day 7 than oil Day 9, but in anestrous cows, no effects of time of the PGF(2 alpha) treatment were found. Estradiol cypionate effectively replaced estradiol benzoate or gonadotropin-releasing hormone as the ovulatory stimulus, reducing labor and cost. In this protocol, CIDR inserts were successfully used four times (9 d each use) with no detrimental effects on fertility. (C) 2009 Elsevier B.V. All rights reserved.

Strategies to improve fertility in postpartum multiparous Bos indicus cows submitted to a fixed-time insemination protocol with gonadotropin-releasing hormone and prostaglandin F-2 alpha

In Exp. 1, we evaluated the effects of 2 lengths of progesterone exposure [CIDR (controlled intravaginal drug release); 7 vs. 14 d] before a modified CO-Synch protocol [50.0-mu g injection of GnRH 6.5 d before a 25.0-mg injection of PGF(2 alpha) followed by another injection of GnRH and fixed-time AI (TAI) 2 d after PGF(2 alpha)], with or without temporary weaning (TW) before GnRH treatments, on fertility of suckled multiparous Bos indicus cows (n = 283) and on calf performance. Timed AI pregnancy rates for cows receiving 7 d CIDR + TW, 7 d CIDR, 14 d CIDR + TW, and 14 d CIDR were 53, 47, 46, and 41%, respectively (P > 0.10). Calves submitted to two 48-h TW 6 d apart had decreased mean BW at 240 d (187.9 +/- 2.7 vs. 195.5 +/- 2.7 kg; P < 0.05), but BW at 420 d was not affected by TW (240.1 +/- 5.1 kg). In Exp. 2, we evaluated the effect of no treatment and treatment with or without a CIDR insert between GnRH and PGF(2 alpha) treatments of a modified CO-Synch protocol on pregnancy rate to TAI, and throughout a 90-d breeding season in suckled multiparous Bos indicus cows (n = 453). The inclusion of a CIDR between first GnRH and PGF(2 alpha) treatments of a modified CO-Synch protocol did not improve pregnancy rate (29 and 33% for cows receiving CO-Synch + CIDR and CO-Synch protocol, respectively), and cycling cows had poorer TAI pregnancy rates than anestrous cows treated with either synchronization protocol (21.7 vs. 40.7%; P < 0.05). However, regardless of treatment with CIDR, cows submitted to TAI protocol had greater (P < 0.05) pregnancy rates at 30 (54.8 vs. 11.2%), 60 (72.1 vs. 38.8%), and 90 d (82.0 vs. 57.9%) of breeding season than untreated cows.