Clinical and histologic evaluation of submerged and nonsubmerged hydroxyapatite-coated implants: a preliminary study in dogs

A clinical and histologic study was performed to evaluate the differences in the healing of submerged and nonsubmerged hydroxyapatite-coated 2-piece implants. Three foxhounds were used for this evaluation. Mandibular premolars 1, 2, 3, and 4 were extracted. Three months later, 2 submerged implants were placed on one side of the mandible, and 2 nonsubmerged implants were placed on the other side of the mandible. After 3 months of healing, the submerged implants were exposed, and a third implant was placed on each side of the mandible in a nonsubmerged procedure. Clinical parameters were recorded, the animals were sacrificed 6 months after placement of the first implants, and histologic and histometric analyses were performed. Results of the evaluation of the clinical parameters showed only minor differences among the different treatment groups. Regarding the percentage of bone-to-implant contact of the different treatment groups, the submerged implants showed a bone-to-implant contact of 63.4%, the nonsubmerged implants showed 70.3% contact, and the late nonsubmerged implants demonstrated a bone-to-implant contact of 58.7%. The average distance from the implant neck to the first bone-to-implant contact (fBIC) for submerged implants was 0.58 mm, for nonsubmerged implants it was 1.09 mm, and it was 1.13 mm for late nonsubmerged implants. The vertical distance between the gingival margin and the apical extent of the junctional epithelium (aJE) varied from 1.14 mm to 1.28 mm in the different groups. The distance from the aJE to fBIC was 1.00 mm for the submerged group, 1.08 mm for the nonsubmerged group, and 1.00 mm for the late nonsubmerged group. Generally, it can be concluded that the clinical and the histologic behavior of submerged or nonsubmerged 2-piece implants utilized in this experiment do not differ.     

Social and biological early life influences on the prevalence of open bite in Brazilian 6-year-olds

OBJECTIVE: Little is known about the effects of social and biological risk factors for open bite on the primary dentition. The aim of this study was to assess the early-life risk factors affecting anterior open bite. METHODS: A cross-sectional study using a birth cohort was carried out in Pelotas, Brazil. A sample of 400, 6-year-old children was employed. The Foster and Hamilton criteria were used to classify open bite. Data concerning social conditions, and perinatal and childhood health and behaviour were obtained from birth to 12 months of age and during the fifth year of the children's lives. Unconditional bivariate and multiple logistic regression analysis were performed. RESULTS: The prevalence of anterior open bite was 46.3%. Risk factors included: a maternal age of between 30 and 39 years, as compared with children whose mothers were younger; breast-feeding for < 9 months; dental caries experience; pacifier sucking between 12 months and 5 years, as compared to no sucking or a shorter duration of sucking; and the presence of finger-sucking at 6 years of age. CONCLUSION: Open bite in the primary dentition was associated with older mothers, early weaning, dental caries occurrence, long-term use of a pacifier and finger-sucking at 6 years of age. These findings support the common risk approach for intervention to prevent open bite in the primary dentition.     

Posttraumatic mandibular deformities

In covering the Emergency Department, the Plastic Surgeon can be faced with the mandibular fracture patient. Although the timely repair of the fracture usually leads to normal function and appearance, occasionally the surgeon is faced with the untoward sequelae of the mandible fracture. Post-traumatic mandibular deformities include non-union, malunion, malocclusion, TMJ dysfuction, and facial asymmetry. The difficulty in treatment of these deformities can be compounded by edentulous mandibles, substance abuse, and approach controversies such as the timing of the repair and surgical versus non-surgical management. Knowledge of the post-traumatic mandibular deformities by the treating physician not only assists in their management but may also allow for their prevention.     

不同浓度复方奥硝唑甲磺酸培氟沙星牙栓的体外抑菌作用的实验研究

目的：观察5种不同浓度（10g／L、20g／L、50g／L、100g／L、200g／L）的复方奥硝唑甲磺酸培氟沙星牙栓的体外抑菌作用。方法：采用Kirby—Bauer纸片扩散法测定5种不同浓度的复方牙栓对牙周主要可疑致病菌的抑菌作用。结果：不同浓度的复方牙栓对牙龈卟啉单胞菌、具核梭杆菌、中间普氏菌、消化链球菌、变形链球菌、金黄色葡萄球菌、表皮葡萄球菌均有一定的抑菌作用。7种菌株间的抑菌圈直径不同、5种不同药物浓度之间的抑菌圈直径也不同，并且菌株和药物浓度两个因素之间存在交互作用（P〈0．001）。上述7种菌株间的F值分别为：91．391、170．431、255．187、143．636、211．839、347．639、580．238（P〈0．001），具有显著性差异。结论：5种不同浓度的复方奥硝唑甲磺酸培氟沙星牙栓在体外均有明显的抑菌作用，以200g／L的给药浓度的抑菌效果最强。     

Collagen fiber orientation near a fractured dental implant after a 5-year loading period: case report

PURPOSE: Fracture of an implant is one of the possible complications of dental implants. It is a quite rare event but of high clinical relevance. Nevertheless, it represents an important opportunity for evaluating the peri-implant bone-tissue response to implant overloading in human beings. The aim of the present study was a scanning electron microscopy evaluation of a screw-shaped implant retrieved because of fracture and a birefringence analysis of the tissue near the fractured implant. MATERIALS AND METHODS: There was 1 fractured screw-shaped implant retrieved from a patient with a trephine bur, and it was processed for histology. The specimen was analyzed under both scanning electron microscopy and circularly polarized light microscopy. RESULTS: The scanning electron microscopy fractography analysis showed the typical signs of a fatigue-fracture, with large plastic deformations on the implant. The fracture seemed to start from the internal coil of the implant. Under circularly polarized light microscopy investigation, a bone-implant contact percentage of 81.6% +/- 1.5% (mean +/- standard deviation) was found. The amount of the transverse collagen fibers was of 68.3%, and the amount of the longitudinal collagen fibers was of 31.7%. The difference was statistically significant for z = 2.247 (P = 0.025). CONCLUSION: The fracture of the implant was most probably correlated to a fatigue of the material mainly associated to a lesion of the internal coil. The high level of bone-implant contact percentage was correlated to a predominant transverse collagen fiber orientation of the collagen fibers in the peri-implant bone.     

Comparison of interfaces between a NiCr alloy and various dental ceramics using transmission electron microscopy (TEM) and 3-point bending test

Several methods (e.g. tensile strength, shear bond strength) have been used in testing metal-ceramic bonds. However, in the interface, structural and analytical investigations can be applied in determining the chemical and phase structure of substances making up the bond. The aim of the present study is to assess the interface between Wiron 99 (Bego) alloy and Vision (Wohlwend) VITA VMK68 (Vita), Carat (Dentsply/DeTrey) ceramic using transmission electron microscopy (TEM) and 3-point bending test. In the case of NiCr alloys, morphologically similar but structurally varying phases developed in all of the ceramics. In each case, a Cr2O3 layer consisting of small crystals (10-20 nm) was noticed with a series of underlying bubble-like amorphous inclusions. The exact three dimensional (3D) location of these structures and their relation to the glass-phase of the ceramic, as well as its role in the nanomechanical anchoring of the ceramic are still to be clarified. The values of debonding stress were 41.67 +/- 5.01 MPa, 52.89 +/- 8.06 MPa and 56.58 +/- 10.21 MPa for Carat, VITA VMK68 ceramic and Vision, respectively. These parameters do not present significant difference at p > or = 0.05 among the three types of ceramics. Based on our measurements it is highly likely that the micromorphology of interface is basically determined by the composition of the alloy while in the chemical composition of the newly developed phases the ceramic and the parameters of firing (temperature, magnitude of vacuum and firing time) play an important role. Values of cracking and morphological resemblance suggest that the superficial micromorphological and nanomorphological structures, acting as mechanical anchoring elements, play an important role in fixing the ceramic.     

Unusual vascular hamartoma of the hard palate. A case report

Hamartomas are tumour-like malformations usually present since birth or which may develop during puberty. Hamartomas are related to anatomical development errors. Hamartomas are rarely found in the head and neck district. The case of an unusual vascular hamartoma localised in the hard palate of a 50-year-old female with no significant medical or family history is reported. Surgical treatment was performed by means of an excisional biopsy.     

Short-term anti-plaque effect of two chlorhexidine varnishes

BACKGROUND: Chlorhexidine (CHX) varnishes have been mainly used for the prevention of caries in high-risk populations. Reports regarding their anti-plaque effect on a clinical level are limited to non-existing as opposed to their microbiological impact on plaque formation. AIM: The aim of this preliminary investigation was to evaluate the anti-plaque effect of two CHX varnishes applied on sound enamel in relation to a positive control, a negative control and to one another. METHODS: Sixteen healthy subjects volunteered for this randomized-controlled, single-blind, four-treatment-four-period crossover-designed clinical trial. A 3-day plaque re-growth model was used to determine de novo plaque accumulation following CHX rinsing, Cervitec application, EC40 application and no therapy. The amount of plaque was measured using the Quigley and Hein plaque index and "automatic image analysis" (AIA). RESULTS AND CONCLUSIONS: Varnish treatment resulted in significantly higher plaque levels than CHX rinsing irrespective of the varnish that was used (p< or =0.002), implying that the latter is likely to remain the gold standard as an anti-plaque agent. However, highly significant differences were also found in favour of both varnish systems when compared with no therapy (p<0.001), which indicates that varnish treatment is an effective means of inhibiting plaque formation in a short time span. Cervitec exhibited slightly, yet significantly, higher plaque levels in comparison with EC40 as determined by AIA (p=0.006). Large-scale trials with a longer observation period are necessary to substantiate these results.     

Effect of evaporation of primer components on ultimate tensile strengths of primer-adhesive mixture.

OBJECTIVE: The purpose of the present study was to evaluate the effect of evaporation of primer components on the ultimate tensile strength (UTS) of primer-adhesive mixtures. METHODS: The UTSs of 1:3 by weight primer-adhesive mixtures and of the pure adhesives (controls) were measured after 0-, 2-, 5-min and 24-h storage in a 37 degrees C oven for the three-step etch&rinse adhesive OptiBond FL (Kerr) and the two-step self-etch adhesive Clearfil SE (Kuraray). RESULTS: Evaporation of primer components increased with time for both adhesives investigated. OptiBond FL showed a higher evaporation of primer components than Clearfil SE at the 2-, 5-min and 24-h storage time. As compared to the pure adhesive, the UTS of the primer-adhesive mixture was lower after 0- and 2-min storage for OptiBond FL and after 0-, 2- and 5-min storage for Clearfil SE. The UTS of OptiBond FL was higher than that of Clearfil SE at the 0- and 2-min storage time, though there was no difference at the 5-min and 24-h storage time. SIGNIFICANCE: The degree of evaporation of primer components depended largely on the primer solvents employed. The significant decrease in UTS of adhesive resin when mixed with primer must be attributed to incomplete evaporation of primer components. Complete evaporation of solvents is hard to achieve, even by thorough air drying.