Prevalence and microscopic features of enamel pearls from permanent human molars

Enamel pearls are ectopic structures observed mainly on the roots of permanent teeth and could be related to periodontal diseases. Aim: To evaluate the prevalence of enamel pearls in extracted human molars and characterize their structures using light and scanning electron microscopy. Methods: The study comprised 2,201 extracted human permanent molars. The teeth were analyzed and classified according to morphological features. The presence, location and shape of enamel pearls were investigated. Fifteen human molars with enamel pearls were embedded in acrylic resin and observed by light microscopy. Results: Seventy-one enamel pearls were identified on third molar root. Microscopically, most pearls were composed of prismatic irregular enamel and normal dentin. The dentinoenamel junction presented an irregular course. The number of dentinal tubules was normal and they presented curvature to continue within the root dentin of the carrier tooth. Dentinal tubules below the enamel pearls were closer to each other. Conclusions: Scanning electron microscopic analysis revealed that the enamel pearls were similar to coronal enamel.

Bonding all-ceramic restorations with two resins cement techniques: A clinical report of three-year follow-up

Ceramics have been widely used for esthetic and functional improvements. The resin cement is the material of choice for bonding ceramics to dental substrate and it can also dictate the final esthetic appearance and strength of the restoration. The correct use of the wide spectrum of resin luting agents available depends on the dental tooth substrate. This article presents three-year clinical results of a 41 years old female patient B.H.C complaining about her unattractive smile. Two all-ceramic crowns and two laminates veneers were placed in the maxillary incisors and cemented with a self-adhesive resin luting cement and conventional resin luting cement, respectively. After a three-year follow-up, the restorations and cement/teeth interface were clinically perfect with no chipping, fractures or discoloration. Proper use of different resin luting cements shows clinical appropriate behavior after a three-year follow-up. Self-adhesive resin luting cement may be used for cementing all-ceramic crowns with high predictability of success, mainly if there is a large dentin surface available for bonding and no enamel at the finish line. Otherwise, conventional resin luting agent should be used for achieving an adequate bonding strength to enamel.

A comparative study of the physical properties of conventional and Grander-modified adhesive systems

Purpose: The objective of this study was to evaluate the influence of the Grander technology in reducing the surface tension and contact angle of a self-etch adhesive system. Methods: Distilled water and Xeno III self-etch adhesive system (Dentsply) were modified by physical contact with the Flexible unit Grander system to revitalize water, for 48 hours, resulting in four groups: Group 1 - Xeno III under normal conditions; Group 2 - Xeno III modified by Grander; Group 3 - distilled water under normal conditions; Group 4 - distilled water system modified by the Grander system;. Surface tension and contact angle (dentin substrate and titanium plate) of the adhesive system and water in normal and Grander-modified conditions was measured with a goniometer. Data were analyzed by ANOVA and Tukey test (5%). Results: Grander technology reduced the surface tension of water but not of the adhesive system Xeno III. The contact angle property of the adhesive ystem was not affected. Conclusion: Grander technology did not interfere with the surface tension and contact angle physical properties of the Xeno III self-etch adhesive system. Copyright: © 2011 Gonçalves et al.;.

Influence of dental exposure to oral environment on smear layer removal and collagen exhibition after using different conditioning agents

Although in vitro studies have shown encouraging results for root surface conditioning with demineralizing agents, in vivo studies have failed to show its benefits in periodontal healing. This can be attributed to several factors, among which, the hypermineralization of dental surface. Therefore, this in vitro study compared, using scanning electron microscopy (SEM), the effect of root surface conditioning with different conditioners (1% and 25% citric acid, 24% EDTA and 50 mg/mL tetracycline hydrochloride) in impacted teeth and in teeth that had their roots exposed to the oral environment. One trained examiner assessed the SEM micrographs using a root surface modification index. There was a tendency of more root surface modification in the group of impacted teeth, suggesting that the degree of root mineralization influences its chemical demineralization.

Influence of cutting instruments and adhesive systems on hybrid layer formation.

Influence of cutting instruments and The aim of this study was to analyze the hybrid layer in noncarious dentin prepared by different cutting instruments and restored with composite resin. The cavities were randomly prepared in 40 specimens using a high-speed diamond bur (KG Sorensen 1013) and an ultrasonic tip (CVDentus C22). The cavities were restored with composite resin by varying the adhesive system between the Adper™ Single Bond (2 x 1 system, primer+adhesive) and the Prompt L-Pop™ (3 x 1 system, self-etching). The restorations were hemisected longitudinally and analyzed in the SEM (Scanning electron microscopy) in order to evaluate the hybrid layer and resinous tags characteristics, using scores ranging from 1 to 6. The Pearson test revealed a high correlation coefficient and good significance levels for both intra- and inter-raters values (r=0.90). The data were statistically analyzed using the Mann-Whitney test (P≤0.05). A larger proportion of regular hybrid layers with numerous tags were observed in the dentin prepared using the high-speed diamond burs and restored with a 2 × 1 adhesive system. Alternatively, the 3 × 1 adhesive system promoted the generation of a thin hybrid layer with few tags. After preparation using an ultrasonic tip revealed few or no tags after the preparation and 2 × 1 or 3 × 1 adhesive system application. The high-speed diamond burs produced a dentin surface that was more favorable to restorative material adhesion than the ultrasonic tips, regardless of the adhesive system used.

Cisalhamento na Linha de Cola de Compensados de Eucalyptus sp. e Adesivo PVA

Studies on new adhesives and resins for bonding wood and wood products are being carried out with the intention to improve their properties, taking into account a lower environmental impact. To this end, new formulations of polyvinyl acetate (PVA) adhesives have been developed, because they have no polluting harmful to health chemicals in their composition, in contrast to formaldehyde-based resins; which in turn are the most commonly used for wood panels production these days. This study tested three different formulations of PVA adhesives, with different pressing times and temperatures for the production of Eucalyptus sp. plywood, obtaining satisfactory results with respect to shear strength at the bondline, which was higher for the PVA adhesives compared to the urea-formaldehyde and phenol-formaldehyde panels found in the literature.

Blood cells attachment after root conditioning and PRP application: An in vitro study

Aim: Root conditioning is aimed at smear layer removal and at dental matrix collagen exposure, which may promote periodontal regeneration. This in vitro study assessed smear layer removal, collagen fiber exposure and the influence of PRP (platelet-rich plasma) application on adhesion of blood cells to the root surface using scanning electron microscopy (SEM). Materials and methods: Scaled root samples (n = 160) were set in five groups and conditioned with: group I - control group (saline solution); group II (EDTA 24%); group III (citric acid 25%); group IV (tetracycline hydrochloride 50 mg/ml); group V (sodium citrate 30%). Eighty samples were assessed using the root surface modification index (RSMI). The other eighty samples were set in two groups. The first group (n = 40) received PRP gel application with a soft brush and the second group (n = 40) received PRP application and then a blood drop. The fibrin clot formation was assessed in the first group and the blood cells adhesion was assessed in the second group using the BEAI (blood elements adhesion index). A previously trained, calibrated, and blind examiner evaluated photomicrographs. Statistical analysis was performed using the Kruskal-Wallis's and Dunn's tests. Results: Group III attained the best results for RSMI and BEAI. Moreover, it was the only group showing fibrin clot formation. Conclusion: Citric acid was the most efficient conditioner for smear layer removal, collagen fiber exposure and blood cell adhesion. Moreover, it was the only group showing fibrin clot formation after PRP application. Clinical significance: This study demonstrated that root conditioning followed by PRP application may favor blood cell adhesion on root surface which may optimize periodontal healing.

Fator de crescimento nervoso em cola de fibrina no reparo término-lateral de nervos em ratos

Purpose: To determine the effects of end-to-side nerve repair performed only with fibrin glue containing nerve growth in rats. Methods: Seventy two Wistar rats were divided into six equal groups: group A was not submitted to nerve section; group B was submitted to nerve fibular section only. The others groups had the nerve fibular sectioned and then repaired in the lateral surface of an intact tibial nerve, with different procedures: group C: ETS with sutures; group D: ETS with sutures and NGF; group E: ETS with FG only; group F: ETS with FG containing NGF. The motor function was accompanied and the tibial muscle mass, the number and diameter of muscular fibers and regenerated axons were measured. Results: All the analyzed variables did not show any differences among the four operated groups (p>0.05), which were statistically superior to group B (p<0.05), but inferior to group A (p>0.05). Conclusion: The end-to-side nerve repair presented the same recovery pattern, independent from the repair used, showing that the addition of nerve growth factor in fibrin glue was not enough for the results potentiating.

Gingival recession associated with noncarious cervical lesions: Combined periodontal-restorative approach and the treatment of long-term esthetic complications

The combined periodontalrestorative approach (that is, a connective tissue graft for root coverage and NCCL restoration with RMGI cement) has demonstrated significant root coverage and a good esthetic outcome. In some cases, though, the color of an RMGI restoration can change over time, compromising esthetics. In this situation, applying composite resin over an RMGI restoration can be a conservative approach to satisfy the patient's esthetic complaint. Long-term observation is necessary to evaluate the stability of the results and establish the success of this approach over time.

Clinical evaluation of a composite resin and a resin-modified glass-ionomer cement in non-carious cervical lesions: One-year results

Objectives: The objective of this study was to evaluate the clinical performance of 124 non-carious cervical lesion restorations at 12 months. Materials And Methods: Three study groups were formed according to the material and technique used. All teeth received 37% phosphoric acid etching in enamel and dentin. The teeth of Group I received the conventional adhesive system Scotch Bond Multi Purpose, followed by resin composite Filtek Z350; teeth of Group II were restored with resin-modified glassionomer cement Fuji II LC; teeth of Group III were restored with the same resin-modified glass-ionomer cement-however, before it was inserted, 2 coats of primer of the Scotch Bond Multi Purpose adhesive system were applied to dentinal tissue. The teeth were evaluated by 2 examiners with regard to the factors of retention, marginal adaptation, marginal discoloration, color alteration, presence of marginal caries lesion, anatomic shape, and sensitivity. Results: Application of the Kruskal-Wallis test showed no statistically significant difference for anatomic shape, marginal discoloration, color alteration, caries lesion, marginal adaptation, and sensitivity among the three study groups, but the variable retention presented statistically significant difference at 12 months, with Group III presenting a behavior superior to that of Group II but similar to that of Group I. Conclusion: The analyzed restorations of non-carious cervical lesions presented a good clinical performance at 12 months. © 2012 Nova Science Publishers, Inc.

Occurrence of sensitivity during at-home and in-office tooth bleaching therapies with or without use of light sources

The aim of this study was to evaluate the effect of tooth bleaching with 10% carbamide peroxide (CP) or 35% hydrogen peroxide (HP), with or without quartz-tungsten-halogen light or hybrid source LED/infrared laser exposition on the occurrence duration, intensity and location of tooth sensitivity Forty patients were selected and randomly divided into four groups: GI--home bleaching with CP for 4 hours a day, over the course of 3 weeks; GII--three sessions of HP with three 10-minute applications at each session and no light source; GIII--the same procedure as GII with quartz-tungsten-halogen light irradiation; GIV--the same procedure as GII with LED/laser light irradiation. The evaluation included an appointment with each patient before and after each HP bleaching session or each weekly CP bleaching and 7, 30 and 180 days after the end of treatment. The Kruskal-Wallis test revealed that the duration and intensity of post-treatment sensitivity were significantly higher for HP than for CP (p< 0.05), and symptoms were located predominantly in anterior teeth. All bleaching methods generated sensitivity, which was more frequent in anterior teeth. However, treatment with CP generated lower sensitivity than treatment with HP independently of the light sources.

Retention and processing methods of nasal prosthesis

Patients with congenital malformations, traumatic or pathological mutilation and maxillofacial developmental disorders can be restored aesthetically and emotionally by the production and use of facial prostheses. The aim of this study was to review the literature about the retention and processing methods of facial prostheses, and discuss their characteristics. A literature review on Medline (PubMed) database was performed by using the keywords maxillofacial prosthesis, silicone, resin, pigment, cosmetic, prosthetic nose, based on articles published from 1956 to 2010. Several methods of retention, from adhesives to the placement of implants, and different processing methods such as laser, CAD/CAM and rapid prototyping technologies have been reported. There are advantages and disadvantages of each procedure, and none can be classified as better compared to others.

Anterior restorations in bleached teeth: Difficulty establishing the color after bleaching

It is becoming more common for patients to look for cosmetic procedures in dental offices. The search for lost or desired esthetics by patients is increasingly frequent and the professional must be able to meet this demand. To do this, dentists not only need to return the tooth back to its normal functioning state but also promote esthetic excellence. In this context, the association of cosmetic procedures, such as teeth whitening and restorative procedures, such as direct adhesive restorations is very common. The composite resins employed nowadays allow the reproduction of various optical properties of natural teeth. With these composite resins, it is possible to reproduce features such as translucency, opacity and specific features of the dental element, to bring back the esthetic harmony of the smile. This article reports a clinical case demonstrating the placement, in a stratified manner, of composite resins in bleached teeth, as well as the reproduction of optical and natural aspects of the teeth. In order to achieve esthetic and functional success of the restored procedure, it is important to be familiar with the new techniques and new materials in the marketand above all, we must know when and where to use them.

Correlation between hybrid layer thickness, resin tag length and microtensile bond strength of a self-etching adhesive system

The purpose of this study was to evaluate the correlation between the hybrid layer thickness, resin tag length and resin bond strength of a self-etching adhesive system to sound dentin tissue in vivo. After performing restorative procedures and tooth extractions, ten specimens were sectioned in a mesiodistal direction. One dental section was used for light microscope analysis, in which both the resin tag length and hybrid layer thickness were measured, while the other section was analyzed using a microtensile test (0.5 mm/min). The fractured surface of the latter section was characterized using a stereoscopic magnifying glass (40x magnifcation). The results were subject to statistical analysis using the Pearson Correlation Test (a = 0.05). The hybrid layer thickness, resin tag length and resin bond strength mean values were 2.19 microm (0.34), 4.34 microm (0.28) and 9.73 MPa (5,55), respectively. In addition, correlation tests between the resin tag length and the resin bond strength (r=0.014) and also between the hybrid layer thickness and bond strength (r=0.43), showed no statistically significant correlation. The microtensile bond strength of Adper Prompt L Pop self-etching adhesive system does not depend on hybrid layer thickness or resin tag length.