Effects of Light Activation, Agent Concentration, and Tooth Thickness on Dental Sensitivity After Bleaching

Examining three bleaching systems, this in vivo clinical trial evaluated the relationship among tooth sensitivity, light activation, and agent concentration, and it correlated dental sensitivity with tooth thickness.Materials and Methods: Eighty-seven volunteer patients were included. Inclusion criteria were the presence of anterior teeth without restorations as well as the absence of a previous bleaching experience and absence of non-carious cervical lesions or dental pain. Exclusion criteria included pregnancy or breastfeeding, a maximum of TF3 hypoplasia, tetracycline-fluorosis stains, malpositioned teeth, orthodontic treatment, periodontal disease, and/or analgesic/anti-inflammatory intake. Patients were randomly assigned to three bleaching groups: Group A (n=25) was treated with 15% H2O2 and nitrogenous-titanium-dioxide and was light activated (Lase Peroxide Lite, DMC, SaoCarlos, Sao Paulo, Brazil); Group B (n=27) was treated with 35% H2O2 and was light activated (Lase Peroxide Sensy, DMC); and Group C (n=35) was treated with 35% H2O2 (White Gold Office, Dentsply, 38West Clark Ave., Milford, USA) without light activation. Tooth sensitivity (TS) was self-reported by the patients using the visual analog scale (VAS) at baseline (TSO), immediately after treatment (TSI), and at seven days after treatment (TS7). In 46 patients, tooth thickness was determined by computed tomography. TSO, TSI, and TS7 were compared between the A and B groups to determine the effect of concentration and between the B and C groups to determine the effect of light using analysis of covariance. The correlation between tooth thickness and TSI was determined by Spearman Rho test (SPSS 15).Results: Eighty-seven patients were evaluated at baseline, and 61 were evaluated at seven days. Separated by groups, tooth sensitivity, expressed as VAS value at the time points TS0, TS1, and TS7, respectively, were as follows: Group A: 13.76 +/- 13.53, 24.40 +/- 25.24, and 5.94 +/- 5.5; Group B: 15.07 +/- 18.14, 42.4 +/- 31.78, and 8.68 +/- 17.99; and Group C: 10.80 +/- 14.83, 31.51 +/- 29.34, and 7.24 +/- 9.2. Group A showed significantly lower tooth sensitivity than group B at TSI (p=0.032). No differences were observed in the tooth sensitivities between groups B and C. No correlation was encountered between tooth thickness and tooth sensitivity immediately after treatment (Rho=-0.088,p=0.563). The median tooth thickness was 2.78 +/- 0.21 mm.Conclusions: Increases in the concentration of bleaching agents directly affect tooth sensitivity, and LED/laser activation and tooth thickness are not correlated with tooth sensitivity after dental bleaching.

Dental anomalies in children submitted to antineoplastic therapy

Cancer is the third most frequent cause of death in children in Brazil. Early diagnosis and medical advances have significantly improved treatment outcomes, which has resulted in higher survival rates and the management of late side effects has become increasingly important in caring for these patients. Dental abnormalities are commonly observed as late effects of antineoplastic therapy in the oral cavity. The incidence and severity of the dental abnormalities depend on the child's age at diagnosis and the type of chemotherapeutic agent used, as well as the irradiation dose and area. The treatment duration and aggressivity should also be considered. Disturbances in dental development are characterized by changes in shape, number and root development. Enamel anomalies, such as discoloration, opacities and hypoplasia are also observed in these patients. When severe, these abnormalities can cause functional and esthetic sequelae that have an impact on the children's and adolescents' quality of life. General dentists and pediatric dentists should understand these dental abnormalities and how to identify them aiming for early diagnosis and appropriate treatment.

Release of Bone Markers in Immediately Loaded and Nonloaded Dental Implants: A Randomized Clinical Trial

The aim of this study was to compare the release of bone markers during osseointegration of immediately loaded and nonloaded implants. Forty patients who were indicated for rehabilitation with dental implants randomly received either implant and prosthesis placement within 72 hours (group IM) or implant insertion and no prosthesis placement (group NL). Peri-implant crevicular fluid was collected immediately after implant insertion and 7, 15, 30, 60, 90, and 120 days after surgery and levels of osteoprotegerin, transforming growth factors, osteocalcin, osteopontin, and parathyroid hormone were evaluated using Luminex assay. Bleeding index and peri-implantar sulcus depth were also evaluated. The data were compared using statistical tests ( = 5%). No statistical difference was found regarding demographic and clinical parameters (p > .05). Transforming growth factors, osteoprotegerin, osteopontin, and parathyroid hormone presented an earlier release peak in group IM than in NL group (p < .05). Osteocalcin achieved higher levels in group IM versus group NL between 7 and 30 days of evaluation (p < .05). It may be concluded that earlier loading positively modulates bone mediators release around immediately loaded implants when compared with nonloaded dental implants (ClinicalTrials.gov NCT01909999).

The Influence of Small Quantities of Oxygen in the Structure, Microstructure, Hardness, Elasticity Modulus and Cytocompatibility of Ti-Zr Alloys for Dental Applications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relationships between growth of the preovulatory follicle and gestation success in lactating dairy cows

This report summarizes three studies conducted with lactating dairy cows aiming to increase pregnancy rates to fixed time artificial insemination (TAI) protocols. Experiment 1 was designed to determine if changing the timing of PGF2 alpha treatment during an E2/P4-based program would affect fertility to TAI or fixed-time embryo transfer (TET). In experiment 2, pregnancy rates to AI were compared following synchronized ovulation using two protocols that have been developed to reduce the period between follicular wave emergence and TAI. The Ovsynch-type protocol utilizes GnRH to synchronize the follicular wave by inducing ovulation of a dominant follicle at the beginning of the protocol, and to synchronize ovulation at the end of the protocol allowing TAI. In contrast, E2/P4-based protocols utilize E2 products in the presence of P4 to induce atresia of antral follicles and synchronize emergence of a new follicular wave. At the end of E2/P4-based protocol another E2 treatment in the absence of P4 is used to induce LH release and synchronize ovulation and allow TAI. Experiment 3 was designed to determine whether increasing the length time interval with reduced circulating P4 (proestrus) would increase fertility in a TAI program that utilized E2 and P4 to synchronize ovulation of cycling, lactating dairy cows. The overall conclusions are that circulating concentrations of progesterone and estradiol prior to and circulating concentrations of progesterone following ovulation can affect fertility in cattle. In addition, small increases in P4 concentrations near the time of AI, due to lack of complete CL regression, result in reductions in fertility. Earlier treatment with PGF2 alpha should allow greater time for CL regression, an increase in estradiol and subsequent reductions in circulating P4 that could be critical for fertility. Optimization of follicle size in TAI programs is clearly an intricate balance between oocyte quality, adequate circulating E2 near AI, and adequate circulating P4 after AI.

Effect of follicle age on conception rate in beef heifers

The objective of this study was to determine the effect of age of the ovulatory follicle on fertility in beef heifers. Ovulation was synchronized with the 5 d CO-Synch + controlled intravaginal drug release (CIDR) program in heifers in Montana (MT; n = 162, Hereford and Angus Crossbred) and Ohio (OH; n = 170, Angus Crossbred). All heifers received estradiol benzoate (EB; 1 mg/500 kg BW, [i.m.]) 6 d after the final GnRH of the synchronization program to induce follicular atresia and emergence of a new follicular wave (NFW) followed by prostaglandin F2 alpha (PGF(2 alpha); 25 mg, i.m.) administration either 5 d (young follicle [YF]; n = 158) or 9 d (mature follicle [MF]; n = 174) after EB. Estrous detection was performed for 5 d after PGF(2 alpha) with AI approximately 12 h after onset of estrus. Ovarian ultrasonography (MT location only) was performed in YF and MF at EB, 5 d after EB, PGF(2 alpha), and AI. Heifers in MT (n = 20) and OH (n = 18) that were not presynchronized or did not initiate a NFW were excluded from further analyses, resulting in 142 and 152 heifers in MT and OH, respectively. Heifers from the MF treatment in MT that initiated a second NFW after EB but before PGF(2 alpha) (MF2; n = 14) were excluded from the primary analysis. In the secondary analysis, the MF2 group was compared to MF and YF treatments in MT. Estrous response was similar (90%; 252/280) between treatments and locations. Proestrus interval (from PGF(2 alpha) to estrus) and age of the ovulatory follicle at AI were similar for MF heifers between locations (54.6 +/- 1.7 h and 8.3 +/- 0.07 h) but were greater (P < 0.01) for YF heifers in OH (78.5 +/- 1.4 h and 5.3 +/- 0.06 h) than MT (67.4 +/- 1.6 h and 4.8 +/- 0.06 h; treatment x location, P < 0.01). However, conception rate did not differ for MF (63.8%; 74/116) and YF (67.0%; 91/136) treatments. In the MT heifers, follicle size and follicle age atAI in the YF treatment (10.4 +/- 0.15 mm and 4.8 +/- 0.06 d, respectively) was less (P < 0.01) than in the MF treatment (11.0 +/- 0.18 mm and 8.3 +/- 0.11 d, respectively), but conception rate to AI did not differ between treatments in MT. In the MF2 group proestrus interval was greater (P < 0.01); hence, diameter of the ovulatory follicle and age were similar to that for the YF treatment. Conception rate to AI did not differ between MF2, MF, and YF (61.5, 63.3, and 64.7%, respectively) in MT. In conclusion, manipulation of age of the nonpersistent ovulatory follicle at spontaneous ovulation did not influence conception rate.

Effect of progesterone concentrations, follicle diameter, timing of artificial insemination, and ovulatory stimulus on pregnancy rate to synchronized artificial insemination in postpubertal Nellore heifers

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

The effect of follicle age on pregnancy rate in beef cows

The effect of the age of the ovulatory follicle on fertility in beef cows was investigated. Multiparous (n = 171) and primiparous (n = 129) postpartum beef cows in 2 groups (G1 and G2) received estradiol benzoate (EB; 1 mg/500 kg BW, intramuscular [i.m.]) 5.5 d (G1; n = 162) and 6.5 d (G2; n = 138) after the final GnRH of a synchronization program (5d CO-Synch + CIDR) to induce emergence of a new follicular wave (NFW), followed by prostaglandin F2 alpha (PGF2 alpha; 25 mg, i.m.) administration either 5.5 d (young follicle, YF; n = 155) or 9.5 d (mature follicle, MF; n = 145) after EB. Estrous detection coupled with AI 12 h later (estrus-AI) was performed for 60 h (MF) and 84 h (YF) after PGF(2 alpha); cows not detected in estrus within this period received timed AI (TAI) coupled with GnRH at 72 and 96 h, respectively. Within the first 72 h after PGF(2 alpha), more (P < 0.01) cows in the MF (76.3%) than YF treatment (47.7%) exhibited estrus, but through 96 h, the proportion detected in estrus (P < 0.05) and interval from PGF(2 alpha) to estrus (P < 0.01) were greater in the YF than MF treatment (88.6% vs. 76.3%, 78.9 +/- 0.8 vs. 57.5 +/- 1.6 h, respectively). Age of the ovulatory follicle at AI was greater (P < 0.01) in the MF (9.32 +/- 0.04 d) than YF (6.26 +/- 0.02 d) treatment, but follicle diameter at AI and pregnancy rates did not differ between MF (13.1 +/- 0.2 mm; 72.0%) and YF (12.9 +/- 0.1 mm; 67.1%) treatments. Regardless of treatment, the diameter of the ovulatory follicle at AI and pregnancy rate were greater (P < 0.01) with estrus-AI (13.1 +/- 0.1 mm; 75.0%) than TAI (12.6 +/- 0.2 mm; 55.4%). Cows in the MF treatment that initiated a second NFW after EB but before PGF(2 alpha) (MF2; n = 47) were induced to ovulate with GnRH and TAI at 72h, when ovulatory follicles were 4 d old and 10.2 +/- 0.2 mm in diameter. Pregnancy rate for TAI (51.1%) in MF2 did not differ from TAI pregnancy rate (55.4%) across the MF and YF treatments. In summary, the age of the ovulatory follicle affected interval to estrus and AI but did not influence pregnancy rate in suckled beef cows.

Influence of Tapered and External Hexagon Connections on Bone Stresses Around Tilted Dental Implants: Three-Dimensional Finite Element Method With Statistical Analysis

Background: The purpose of this study is to analyze the tension distribution on bone tissue around implants with different angulations (0 degrees, 17 degrees, and 30 degrees) and connections (external hexagon and tapered) through the use of three-dimensional finite element and statistical analyses.Methods: Twelve different configurations of three-dimensional finite element models, including three inclinations of the implants (0 degrees, 17 degrees, and 30 degrees), two connections (an external hexagon and a tapered), and two load applications (axial and oblique), were simulated. The maximum principal stress values for cortical bone were measured at the mesial, distal, buccal, and lingual regions around the implant for each analyzed situation, totaling 48 groups. Loads of 200 and 100 N were applied at the occlusal surface in the axial and oblique directions, respectively. Maximum principal stress values were measured at the bone crest and statistically analyzed using analysis of variance. Stress patterns in the bone tissue around the implant were analyzed qualitatively.Results: The results demonstrated that under the oblique loading process, the external hexagon connection showed significantly higher stress concentrations in the bone tissue (P < 0.05) compared with the tapered connection. Moreover, the buccal and mesial regions of the cortical bone concentrated significantly higher stress (P < 0.005) to the external hexagon implant type. Under the oblique loading direction, the increased external hexagon implant angulation induced a significantly higher stress concentration (P = 0.045).Conclusions: The study results show that: 1) the oblique load was more damaging to bone tissue, mainly when associated with external hexagon implants; and 2) there was a higher stress concentration on the buccal region in comparison to all other regions under oblique load.

Social aspects of dental caries in the context of mother-child pairs

The relationship between mother and child in the context of oral health has traditionally been exposed by the scientific literature in microbiology, which lacks a broad and necessary discussion of health and illness seen as processes, both biological and social. Objective: Investigate the family social determinants associated with the caries history of children and the need for dental treatment (NDT) among their mothers was the objective of this study. Material and Methods: This research employed a cross-sectional study of mother-child pairs living in southern Brazil. Data collection occurred in public institutions of early childhood education. The instruments included a structured questionnaire administered to mothers and clinical oral examinations of the mothers and children. The social variables considered were marital status, maternal education, number of children, income, employment status, and frequency of visits to a dental professional. The measured outcomes were the maternal NDT and child caries history. Data were analyzed by the chi-square test (chi 2) and by discriminant analysis. Results: The final sample consisted of 272 mother-child pairs and it was found that the greatest need for treatment was among mothers with low educational level and low family income who rarely or never visited a dentist. Tooth decay was less frequent in only child, and most frequent in children of mothers with low educational attainment, and in children in lower income households who rarely or never visited the dentist. The social determinants of caries in children and of the maternal NDT were similar. It follows that the maternal NDT and caries history among children were strongly associated with maternal education (p<0.0001), household income (p<0.0001), and frequency of visits to a dental professional (0.0018). Caries history among children was also associated with number of children in the household (p<0.0001). Conclusions: The results suggest that the caries experience in children depended less on the family social variables than on the maternal NDT.

Infrared LED irradiation photobiomodulation of oxidative stress in human dental pulp cells

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

Comparison of changes in dental and bone radiographic densities in the presence of different soft-tissue simulators using pixel intensity and digital subtraction analyses

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

Mechanical behavior of dental implants in different positions in the rehabilitation of the anterior maxilla

Statement of problem. In dental rehabilitations that involve implants, the number of implants is sometimes smaller than the number of lost teeth. This fact can affect the biomechanical behavior and success of the implants.Purpose. The purpose of this study was to investigate the mechanical behavior of different implant positions in the rehabilitation of the anterior maxilla.Material and methods. Three-dimensional models of the maxilla were created based on computed tomography images for 3 different anterior prosthetic rehabilitations. In group IL, the implants were placed in the lateral incisor positions with pontics in the central incisor positions; in group IC, the implants were in the central incisor positions with cantilevers in the lateral incisor positions; and, in group ILIC, one implant was in a lateral incisor position and one was in a central incisor position, with a pontic and a cantilever in the remaining positions. A 150 N load was distributed and applied at the center of the palatal surface of each tooth at a 45-degree angle to the long axis of the tooth. The resulting stress-strain distribution was analyzed for each group.Results. The lowest displacement of the prosthetic structure was observed in group IC, although the same group exhibited the largest displacement of the bone tissue. In the bone tissue, the von Mises stress was mainly observed in the cortical bone in all groups. The maximum value of the von Mises stress shown in the cortical tissue was 35 MPa in the implant that neighbors the cantilever in group ILIC. The maximum von Mises stress in the trabecular bone was 3.5 MPa.Conclusion. The prosthetic configuration of group IC limited the displacement of the prosthetic structure but led to greater displacement of the bone structure. The use of a cantilever increased the stress concentration in the implant and in the bone structure adjacent to the cantilever under the conditions studied here.