George Gomes

Sealing Ability of Three Fiber Dowel Systems

PURPOSE To study the sealing ability of two new fiber dowel systems. MATERIALS AND METHODS Thirty-six extracted single-rooted teeth were endodontically treated and randomly assigned to two new fiber dowel systems and a control group: (1) an E-glass-based dowel, everStick-POST, cemented with ParaCem Universal DC resin cement (EV); (2) a glass-fiber dowel, RelyX Fiber Post, cemented with RelyX Unicem self-adhesive resin cement (RX). The control group was restored with a glass-fiber dowel, ParaPost Fiber Lux, cemented with ParaCem Universal DC resin cement (PP). The roots were isolated and immersed in a 50 wt% ammoniacal silver nitrate solution for 24 hours followed by 8 hours in a photo-developing solution. The roots were sectioned in 1-mm-thick disks perpendicular to the long axis of the root. The specimens were processed for backscattered FESEM observation. For each tooth, the depth of silver infiltration into the root canal was measured by ranks from 0 to 8. For each disk, silver infiltration was measured as the percentage of leakage around the adhesive interface. Data were analyzed with Kruskal-Wallis nonparametric tests at a significance level of 95%. RESULTS When the silver infiltration was computed from the coronal to the apical aspects of the root, RX resulted in the lowest degree of silver infiltration, but not statistically different from that of EV (p < 0.148). RX, however, resulted in a lower depth of silver infiltration than the control group PP at p < 0.023. EV resulted in a statistically similar depth of penetration to PP (p= 0.492). Although the total mean percentage of silver infiltration at the dentin-resin cement interface was statistically similar for all groups (p= 0.632), EV resulted in the greater number of disks with silver infiltration (23 out of 96), followed by PP (21 out of 96) and RX (14 out of 96). None of the specimens showed leakage around the dowel-resin cement interface. CONCLUSION The use of the E-glass dowels in EV did not improve the root-wall sealing ability compared with the control group PP. The system RX, which uses a new simplified self-adhesive protocol, resulted in a lower depth of silver infiltration than the control group PP.

Prefabricated Composite Resin Veneers - A Clinical Review

OBJECTIVE This clinical technique article is focused on the use of prefabricated veneers to enhance the esthetic appearance of the anterior dentition in patients who needed an alternative esthetic solution more affordable than traditional porcelain veneers. CLINICAL CONSIDERATIONS Because prefabricated composite veneer systems have been recently introduced, they are not widely used. The Componeer system (Coltene, Altstätten, Switzerland) contains thin pre-polymerized hybrid composite shells, several shades of a direct hybrid composite resin, an etch-and-rinse adhesive system, and restorative accessories including finishing points and disks. The prefabricated restorations can be customized in the mouth for color and shape. The technique described in this article can be used to restore function and esthetics in one office visit. CONCLUSIONS The prefabricated composite veneer technique has some of the advantages of direct composite restorations, as only one session is required without the need to take impressions to send to the dental laboratory. This new treatment option may open new opportunities for dental professionals and their patients. However, it is paramount to carry out controlled clinical studies with this restorative technique prior to recommending it without restrictions in general practice. CLINICAL SIGNIFICANCE The clinical technique described in this paper has the potential for being used routinely to lengthen anterior teeth, to correct malpositioned teeth, to mask discolorations, and to close diastemas. The technique can also be used to restore extensive caries lesions and tooth fractures, and to refurbish large old anterior restorations, especially when other treatment options are out of reach for the patient for financial reasons.

Direct Resin-Based Composite Restorations — Clinical Challenges

With the increase in esthetic awareness and the widespread use of adhesive techniques, a resin composite has become the material of choice for anterior and posterior restorations. In spite of its advantages, polymerization shrinkage and the resulting stress are still a concern for clinicians. The shrinkage stress may cause cusp deflection, interfacial debonding or enamel cracks, leading to microleakage, post-operative sensitivity and secondary caries. The micro-mechanical nature of the interaction of dental adhesives with enamel and dentin is a result of the infiltration of resin monomers into the microporosities left by the acid etching and subsequent enveloping of the exposed enamel hydroxyapatite crystals and the dentin collagen fibers with the resulting polymer. The latest development in dental adhesives is based on simplification and reduced application time of the bonding procedure by using non-rinsing adhesives. These non-rinsing (or self-etch) adhesives do not require a separate acid-etch step as they condition and prime enamel and dentin simultaneously by infiltrating and partially dissolving hydroxyapatite to generate a resin-infiltrated zone with minerals and smear layer incorporated. In spite of their user-friendliness and low technique sensitivity, self-etch adhesives have resulted in low bonding effectiveness, behaving as semi-permeable membranes to allow movement of water across the dentin–resin interface and potentially leading to hydrolytic degradation. Recently, the role of metalloproteinases (MMPs), in inducing degradation of the dentin extracellular matrix components, has been highlighted in the literature along with the potential role of chlorhexidine in inhibiting the deleterious role of MMPs. The ultimate goal of a bonded restoration is to attain an intimate adaptation of the restorative material with the dental structure. This task is difficult to achieve as the bonding procedure is different for enamel and for dentin. The bonded interface undergoes degradation with time when a hermetic seal is not achieved. On the other hand, an improved sealing results in decreased post-operative sensitivity and higher resistance to the caries process. The stress resulting from the polymerization shrinkage of resin composites is also a factor that interferes with the bonding procedure as it may cause interfacial leakage and cusp deflection.

Bond strength and nanoroughness assessment on human pretreated cementum surfaces.

OBJECTIVES To determine the bond strength of seven adhesive systems to human cementum, and to assess the promoted surface roughness. METHODS Extracted human canines were used for the present study. The mesial surface from the cervical third of the roots were ground flat with wet 600-grit silicon carbide paper and bonded. Seven adhesive systems were employed: an etch-and-rinse adhesive (Single Bond), two two-step self-etching (Clearfil SE Bond and Resulcin Aquaprime) and four one-step self-etching (One-up Bond F, Prompt-L-Pop, Etch and Prime 3.0 and NRC+Prime&Bond NT). Composite build-ups were constructed and stored in a humid environment for 24h at 37 degrees C. Specimens were sectioned into 1mm(2) beams and tested for microtensile bond strength (MTBS). Additional surfaces were conditioned for atomic force microscopy (AFM) analysis. Results were analyzed with ANOVA and Student-Newman-Keuls tests (P<0.05). RESULTS Single Bond showed the highest MTBS values. No differences were found between Resulcin Aquaprime, One-up Bond and Prompt-L-Pop. Clearfil SE Bond, Etch and Prime and NRC+Prime&Bond NT obtained the lowest bond strength values. H(3)PO(4) acid treatment of cementum and Resulcin Aquaprime showed the highest nanoroughness parameters and One-up Bond the lowest. CONCLUSION The etch-and-rinse adhesive and the two-step self-etching adhesive with the lowest pH value promoted the highest bond strength to human cementum surfaces.

At-Home Tray Whitening and Resin Infiltration After Acid Etching with HCl

The treatment of discolored anterior teeth may involve combined techniques. This clinical sequence illustrates the successful bleaching of “yellow” teeth with at-home whitening using 10 % carbamide peroxide in a custom-fitted tray, followed by masking idiopathic white spots with enamel etching with HCl followed by resin infiltration.

Intracoronal Whitening of Endodontically Treated Teeth

Several techniques have been used within the last 170 years to lighten discolored endodontically treated teeth. Internal whitening or intracoronal whitening offers some advantages over more invasive treatments, as: (1) it is relatively easy to carry out; (2) it involves the removal of minimal tooth structure; and (3) the cost of treatment is low compared to that of other restorative options including full- and partial-coverage restorations.

At-Home Tray Whitening and Direct Resin-Based Composite Restorations

As discussed in Chap. 6, the esthetic appeal of anterior teeth may benefit from at-home whitening prior to esthetic rehabilitation with veneers or prior to recontouring clinical crowns with direct resin-based composite restorations. This clinical case illustrates the treatment details of a patient who wanted to change the color and the length of her anterior teeth.