Effects of a local single dose administration of growth hormone on the osseointegration of titanium implants.

BACKGROUND: The aim of the present study was to evaluate the effect of different concentrations of growth hormone (GH) on endosteal implant's surface at the early stages of osseointegration. MATERIAL AND METHODS: Sixty tapered acid-etched titanium implants were divided into four groups: i) Collagen, used as a control group; and three experimental groups, where after collagen coating, GH was administered directly to the surface in varying concentrations: ii) 0.265 mg, iii) 0.53 mg, and iv) 1 mg. Implants were placed in an interpolated fashion in the anterior flange of C3, C4 or C5 of 15 sheep with minimum distance of 6 mm between implants. After 3-, 6- and 12-weeks of healing samples were harvested, histologically processed, qualitatively and quantitatively assessed for bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). RESULTS: Statistical analysis as a function of time in vivo and coating resulted in no significant differences for BIC and BAFO at any evaluation time point. Histological evaluation demonstrated similar osseointegration features for all groups with woven bone formation at 3 weeks and progressive replacement of woven for lamellar bone in close contact with the implant surface and within the implant's threads. CONCLUSIONS: A single local application of growth hormone to the surface of titanium implants did not yield improved implant osseointegration independent of healing time.

Effect of Tribochemical Coating on Composite Repair Strength.

CLINICAL RELEVANCE: Tribochemical treatment of existing composite surfaces is highly effective for composite repair. When repairing an old composite restoration, the clinician should try to use the same composite originally used for the restoration. If the information about the original restoration is not known, a composite with strong mechanical properties should be used for the repair restoration. SUMMARY: This study evaluated the effect of tribochemical coating on composite-to-composite repair interfacial fracture toughness (iFT). Sixty beam-shaped specimens (21×4×3 ± 0.2 mm) were prepared with a nanofill composite (Filtek Supreme Ultra [FSU]) and a nanohybrid composite (Clearfil Majesty ES-2 [CME]) and aged for 50,000 thermocycles (5°C-55°C, 20-second dwell time) and then sectioned in half. The resulting 120 hemispecimens (60 for each composite) were randomly assigned to different repair methods (n=10): universal adhesive (Clearfil Universal Bond Quick [CUB]), sand-blasting followed by CUB, or tribochemical coating (CoJet, CoJet sand, Espe-Sil, and Visio-Bond). The repair surface was prepared with a diamond bur (Midwest #471271), rinsed, and dried. Each aged composite brand (FSU, CME) was repaired with either the same composite or the opposite composite. All adhesives and composites were light cured with a high-irradiance LED curing light (Elipar DeepCure-S). After postrepair storage in 100% humidity and at 37°C for 24 hours, iFT was measured as KIc (MPa m½). Data were analyzed for statistical significance using two-way analysis of variance (ANOVA) and the Tukey honest significant difference post hoc test (α=0.05). Regardless of the substrate composite, ANOVA showed significant differences for surface treatment (p<0.0001) and repair composite (p<0.0001). Mean iFT values (SD) ranged from 0.91 (0.10) MPa·m½ to 2.68 (0.12) MPa·m½. Repairs made with FSU after CoJet resulted in significantly higher iFT (FSU: 2.68 MPa·m½; CME: 2.21 MPa·m½) when compared to the other experimental groups. The repair iFT was higher with CoJet treatment and when the nanofill composite FSU was used as the repair composite.

Does the addition of potassium nitrate to carbamide peroxide gel reduce sensitivity during at-home bleaching?

BACKGROUND: A systematic review with meta-analysis was conducted to assess the effect of adding potassium nitrate to carbamide peroxide gels on bleaching efficacy and on reducing the risk and intensity of tooth sensitivity. METHODS: PubMed, Scopus, Web of Science, LILACS, BBO, and Cochrane Library databases and the gray literature were searched. IADR abstracts, records of trials, dissertations and theses were also searched. The Cochrane Collaboration risk of bias tool was used to assess the quality of the studies. RESULTS: Six studies were included in the systematic review and most of them had unclear risk of bias for the key domains, and of these only five were included in the meta-analysis. The risk ratio (RR) for sensitivity was 0.93 (95% CI = 0.73 to 1.19, P = 0.56). The standardized mean difference for pain intensity was -0.10 (95% CI = -0.36 to 0.16, P = 0.45), and for colour change was 0.12 (95% CI = -0.22 to 0.46; P = 0.49). CONCLUSIONS: No significant differences were observed between the groups with and without addition of the desensitizer in the gel. The addition of potassium nitrate to carbamide peroxide gel did not reduce the risk and intensity of tooth sensitivity during at-home bleaching. Colour change was not influenced by the addition of potassium nitrate to the gel.

Efficacy of a Light-cured Tetracaine-based Anesthetic Gel for Rubber Dam Clamp Placement: A Triple-blind Randomized Clinical Trial.

OBJECTIVES: To evaluate the efficacy of a new light-cured anesthetic gel for pain control in adults undergoing rubber dam isolation for the restorative treatment of noncarious cervical lesions (NCCLs). METHODS AND MATERIALS: This study was a randomized, split-mouth, triple-blind, controlled trial. The sample comprised 50 adults with at least one pair of NCCLs located in the same arch but on opposite sides. Simple randomization defined the tooth to receive the light-cured tetracaine-based anesthetic gel or the placebo gel. After cotton roll isolation, the gels were applied in the gingival tissue around the tooth with the aid of the applicator tip of a syringe, left in place for 15 seconds, and light-cured for 15 seconds. Then, a #212 clamp was positioned on the tooth. If the patient reported pain, the clamp was removed, the patient filled out a pain intensity form (a 0-10 visual analog scale [VAS] and a 0-4 verbal rating scale [VRS]) and an injectable anesthetic was applied before rubber dam isolation for the restorative procedure. The absolute risk, intensity of pain, and need for rescue anesthesia were analyzed by the McNemar test and the Wilcoxon signed rank test (α=5%). RESULTS: The odds ratio [OR] for pain (OR=3.5; 95% confidence interval [CI]=1.1 to 14.6; p=0.03) showed lower reports of pain for the light-cured anesthetic gel. One in five patients will benefit from placement of the light-cured anesthetic gel. On average, pain intensity was one VAS unit lower in those using the light-cured anesthetic gel than in those using the placebo gel. For the VRS, the pain intensity for the light-cured anesthetic gel was 0.4 units lower than the pain intensity for the placebo gel (95% CI=-0.9 to 0.07). The OR for rescue anesthesia was 2.5 (95% CI=0.7 to 10.9; p=0.18). CONCLUSIONS: The light-cured, tetracaine-based anesthetic gel reduced the absolute risk of pain by 20% in NCCLs.

Composite-composite Adhesion as a Function of Adhesive-composite Material and Surface Treatment.

OBJECTIVE: To evaluate the composite-to-composite repair interfacial fracture toughness (iFT) as a function of adhesive and composite repair material. METHODS AND MATERIALS: Beam-shaped composite specimens (21×4×3±0.2 mm) were prepared for each substrate material (Filtek Supreme Ultra [FSU] or Clearfil Majesty ES-2 [CME]) and artificially aged for 50,000 thermocycles (5-55°C, 20-second dwell time). Aged specimens were sectioned in half, and the resulting hemispecimens were randomly assigned to one of the different repair methods (n=10) based on the following variables: type of substrate composite (FSU or CME), acid etch (yes or no), adhesive type (Scotchbond Universal or Clearfil SE Bond 2), and type of repair composite (FSU or CME). The repair surface was prepared with a course diamond bur (Midwest #471271). When used, 37% phosphoric acid was applied for 20 seconds, rinsed, and dried. All adhesives and composites were applied according to manufacturers' instructions. After postrepair storage (100% humidity, 37°C, 24 hours), iFT was measured and expressed as MPa. Data were analyzed for statistical significance using a three-way analysis of variance and Tukey post hoc tests (α=0.05). RESULTS: iFT values ranged from 0.64 ± 0.19 MPa to 1.28 ± 013 MPa. Significantly higher iFT values were achieved when FSU was used as the repair composite resin regardless of the substrate composite resin (p<0.001). Clearfil SE Bond 2 adhesive was associated with significantly higher iFT values for FSU substrate (p<0.001). The etching procedure had no significant effect on the iFT values of the repair procedures (p>0.05). CONCLUSIONS: Composite repair strength is adhesive and composite dependent. Repair strength appears to be higher when FSU is the repair composite regardless of the adhesive used.

L-PRP diminishes bone matrix formation around autogenous bone grafts associated with changes in osteocalcin and PPAR-γ immunoexpression.

Leucocyte- and platelet-rich plasma (L-PRP) is an autogenous platelet concentrate enriched with leukocytes that releases various growth factors responsible for the proliferation, regulation, and differentiation of mesenchymal cells during wound healing. Since the bone and medullary tissue are contiguous and share the same origin, this study evaluated the effect of L-PRP on the repair of calvaria bone using histomorphometric analysis of the newly formed bone, and compared the results in the presence of osteocalcin (OC) and peroxisome proliferator-activated receptor gamma (PPAR-γ) detected by immunohistochemistry. Artificial circular bone defects (5mm diameter) were produced in the calvaria of 42 rats. The defects were treated with autograft, autograft combined with L-PRP, or without grafting material (sham). The animals were euthanized at 15 or 40 days postsurgery (n=7 in each group). Data obtained were analyzed by Student-Newman-Keuls test for histomorphometric and immunohistochemical interpretation. The development of bone matrix was significantly less in the defects treated with L-PRP, while the medullary area composed of fatty cells was larger. This coincided with the minor expression of OC and expressive presence of PPAR-γ. These results suggest that L-PRP may impair osteoneogenesis and alter the ratio of differentiation between bone matrix and fatty cells, increasing the medullary tissue.

Mechanical properties of resin cements with different activation modes.

Dual-cured cements have been studied in terms of the hardness or degree of conversion achieved with different curing modes. However, little emphasis is given to the influence of the curing method on other mechanical properties. This study investigated the flexural strength, flexural modulus and hardness of four proprietary resin cements. Materials tested were: Enforce and Variolink II (light-, self- and dual-cured), RelyX ARC (self- and dual-cured) and C & B (self-cured). Specimens were fractured using a three-point bending test. Pre-failure loads corresponding to specific displacements of the cross-head were used for flexural modulus calculation. Knoop hardness (KHN) was measured on fragments obtained after the flexural test. Tests were performed after 24 h storage at 37 degrees C. RelyX ARC dual-cured showed higher flexural strength than the other groups. RelyX ARC and Variolink II depended upon photo-activation to achieve higher hardness values. Enforce showed similar hardness for dual- and self-curing modes. No correlation was found between flexural strength and hardness, indicating that other factors besides the degree of cure (e.g. filler content and monomer type) affect the flexural strength of composites. No statistical difference was detected in the flexural modulus among the different groups.

Tensile bond strength of filled and unfilled adhesives to dentin.

PURPOSE: To determine the tensile bond strength of three filled and two unfilled adhesives applied to bovine dentin. MATERIALS AND METHODS: Fragments of the labial dentin of bovine incisors were embedded in PVC cylinders with self-cure acrylic resin, and ground flat using 200 grit and 600 grit sandpaper. The following adhesive systems were tested (n=10): Prime & Bond NT, Prime & Bond NT dual cure, Prime & Bond 2.1, OptiBond Solo and Single Bond. A 3 mm-diameter bonding surface was delimited using a perforated adhesive tape. After etching with 37% phosphoric acid and adhesive application, a resin-based composite truncated cone (TPH, shade A3) was built. Tensile test was performed after 24 hrs storage in distilled water at 37 degrees C. Failure mode was accessed using a x10 magnification stereomicroscope. RESULTS: Weibull statistical analysis revealed significant differences in the characteristic strength between Single Bond and Prime & Bond NT dual cure, and between Single Bond and Prime & Bond 2.1. The Weibull parameter (m) was statistically similar among the five groups. Single Bond and Prime & Bond NT showed areas of dentin cohesive failure in most of the specimens. For OptiBond Solo, Prime & Bond NT dual cure and Prime & Bond 2.1 failure was predominantly adhesive.