Quintessence International, 07/2003

Objective: Glass-fiber-reinforced resin composites for the fabrication of esthetic single crowns and fixed partial dentures have been developed recently. However, little data on the clinical outcome of such restorations have been published. The purpose of this retrospective study was to evaluate the clinical outcome of crowns and fixed partial dentures made from the glass-fiber-reinforced resin composite material Targis/Vectris. Method and materials: Between 1995 and 1997, 39 patients were treated with 67 single crowns and 83 fixed partial dentures. Twenty-five crowns and 28 fixed partial dentures were cemented with temporary cement, while 42 crowns and 55 fixed partial dentures were cemented with either zinc-phosphate cement or glass-ionomer cement. Results: In September 2001, 57 restorations in 17 patients were still in function. The three-year survival rate calculated according to the Kaplan-Meier method was 58.8% for all restorations. However, after this time, it was 37.5% for crowns and 59.9% for fixed partial dentures cemented with temporary cement, and 55.1% for crowns and 67.9% for fixed partial dentures cemented with zinc phosphate or glass ionomer. The differences between the restoration groups were not statistically significant. Conclusion: Glass-fiber-reinforced crowns and fixed partial dentures made with the glass-fiber-reinforced resin composite material Targis/Vectris showed a lower survival rate than that published for metal-ceramic crowns and fixed partial dentures. Therefore, the use of this material for the fabrication of single crowns or fixed partial dentures as permanent restorations cannot be recommended.

Objectives: The microflora around and beneath restorations is an important factor of restoration failure. The aim of this pilot study was to determine and compare the microbial spectrum under composite and amalgam restorations with special attention to the anaerobic flora. Method and materials: Ten composite and five amalgam restorations scheduled for replacement were clinically evaluated for marginal gaps, fractures, and secondary caries. After their removal and caries diagnosis, a dentin sample just below the restoration was taken under sterile conditions, stored in a prereduced transport medium for anaerobic bacteria, and immediately transferred to a laboratory for microbial diagnosis. Results: The clinical parameters showing mostly moderate marginal imperfections and the ratios of aerobic to anaerobic flora were comparable for composite and amalgam restorations (11.4%:88.6% and 15.4%:84.5%, respectively). The microbial variety under composite restorations was much greater compared to amalgam, and it was similar to that of infected root canals including anaerobic gram-negative rods, such as Fusobacterium species or Porphyromonas species Beneath amalgam, the microbial flora was similar to the one found in carious dentin and plaque, with anaerobic and facultatively anaerobic gram-positive rods dominating. Quantitatively, there were up to eight times more microorganisms under composite restorations. The number of bacterial strains correlated with the caries activity and the filling material, the number of anaerobic rods correlated highly with caries activity and localization. In a linear regression, caries activity and the filling material had statistically significant influence on the bacterial load. Conclusion: Although caries activity and location had the greatest influence on the microbial flora under the restorations, the kind of restoration material seemed to have an additional effect on the composition of the microflora. This pilot study indicates that inadequate composite restorations may promote the growth of cariogenic, as well as obligate anaerobic and potentially pulpopathogenic bacteria, which should be confirmed by further studies.

Objectives: The aim of this study was to investigate the effect of pre- and postoperative bleaching with 10% carbamide peroxide on marginal leakage of amalgam and resin composite restorations. Method and materials: Three groups were made using 30 extracted, caries-free third molars (n = 10). In the preoperative group, bleaching was performed with 10% carbamide peroxide, followed by the placement of resin composite and amalgam restorations on Class V cavity preparations. In the postoperative group, bleaching was performed after the resin composite and amalgam restorations were fabricated. The third group served as a control in which no bleaching was performed. Dye penetration was used for evaluation of marginal leakage. Results: Chi-square test showed that marginal leakage of resin composite restorations increased in both pre- and postoperatively bleached groups, but marginal leakage of amalgam restorations showed no alterations. Conclusion: Bleaching with carbamide peroxide may alter the marginal leakage of resin composite restorations, but amalgam restorations are not affected adversely in vitro.

Dental invagination or dens in dente is a rare malformation with a widely varied morphology. Radiographically, the affected tooth shows an infolding of the enamel and dentin that can extend to within the pulp cavity and the root and sometimes to the root apex. It can occur in both primary and permanent teeth, and its prevalence is reported to be 1.7% to 10%. The dental anomalies observed in association with dental invagination include taurodontia, microdontia, supernumerary teeth, gemination, and dentinogenesis imperfecta. This article presents a clinical case in which a radiographic finding could be compatible with the presence of a nasopalatine or globulomaxillary cyst and a dens in dente. It was decided to extract the invaginated tooth, and by 15 days postextraction, the radiolucid area had completely disappeared. The complex surgery that would have been required to remove the patient's supposed cyst was thus avoided. Clinical and radiographic examination is suggested before making further decisions that could complicate treatment when a lesion is associated with other dental anomalies.

The demand for dental treatment by human immunodeficiency virus (HIV)-infected individuals is rising. Some professionals are still reluctant to treat these patients, despite the extremely low likelihood of professional transmission, which increases only in patients with a very elevated viral load. The complications rate after dental intervention is very low, even in patients with considerable immunologic deterioration. The dentist should pay special attention to the general clinical situation and immunologic and HIV virologic status of the seropositive patient, and to the presence of hemostasis alterations or of other concomitant diseases. Antiretroviral or any other drug treatments must also be recorded, in order to avoid possible interactions with clinician-prescribed drugs. Tooth extraction is the most common dental treatment and requires no antibiotic therapy except in cases of neutropenia or severe immunosuppression. Other dental treatments do not require special precautions, and the complications index among these patients is similar to that among the uninfected patient population. With this background, there is a need to make the clinician-in-training aware of the importance of regular dental health checkups as part of the health care routine of HIV-infected patients and to familiarize the clinician with their management, while not disregarding the unquestionable requirement to carry out the general and specific prevention measures to be adopted in all cases.

Objective: Tooth deflections under functional loads are considered to be the etiologic factor of noncarious cervical lesions. There are several studies on the materials used to restore these lesions; however, there are few discussing this phenomenon's etiology from a biomechanic point of view. This study was undertaken to evaluate tooth behavior when forces were applied from different directions. Method and materials: A 3D finite element model of a maxillary central incisor was designed. A distributed force of 1.5 N was applied on the palatal side of the crown in five stages, with varying directions progressing from tipping to intrusion. Two separate approaches (displacement and stress) were considered to evaluate the cervical area from a stress perspective. Results: The displacement approach resulted in a curved path when compared to a straight line connecting the apical and incisal areas. The maximum deflections were in the cementoenamel junction area. The same area was shown to undergo the maximum of von Mises stress and stress intensity. Patterns of the von Mises stress when evaluated in a mesiodistal direction were in complete agreement with the shape of the cervical lesions (except for the application of the intrusive force, which rules out its effect in producing such lesions). Conclusion: Force applications, except for intrusive force, can produce increases in the von Mises stress and tooth deflections that can answer the question of the etiology of noncarious cervical lesions. The highest amounts of deflection and von Mises stress were produced by the 45-degree force application.

Objective: To compare the application of ultrasound with the use of an engine-driven trephine bur to remove parallel-sided root canal posts. Method and materials: Single-rooted human canine teeth were decoronated and prepared to receive preformed titanium posts. The posts were cemented with Panavia F resin cement. Ten teeth acted as controls, 10 had a 4-mm-deep gutter cut around the post using a Masserann trephining bur, and 10 were subjected to 10 minutes of ultrasound. The forces required to dislodge the posts were determined using a universal testing machine, and the data were analyzed using analysis of variance. Results: The only significant difference was between the trephined and ultrasonically energized groups, with the ultrasonic group requiring greater forces for dislodgement. Conclusion: Resin composite cement could be removed from around the posts with the trephine bur but with considerable difficulty, and neither method of dislodging the posts was effective.

Objective: This study examined the effect of anterior and middle superior alveolar (AMSA) field block of maxillary nerves using a new local anesthetic system-the Wand. Method and materials: Twenty healthy volunteers aged 23 to 44 years were used in the study. Either side of the maxillary teeth was randomly selected for AMSA injection; the other side was left as a control. For each side, 1.8 mL of 2% lidocaine solution with 1/80,000 epinephrine was injected by the Wand on a point that bisects the maxillary first and second premolars and is midway between the crest of the free gingival margin and the midpalatine suture. Pain rating score (PRS) and visual analogue scale (VAS) were applied for measurement of puncture, insertion, and injection pain. Electric pulp stimulation was given to each maxillary tooth every 10 minutes for 1 hour after the injection in order to find out the specific tooth on which AMSA injection was effective. Results: During needle insertion, 14 out of 20 subjects answered moderate pain and VAS showed 27.3 mm (mean). During injection, 11 of 20 revealed no pain and the mean of VAS was 14.5 mm. No one claimed severe pain by PRS. Electric pulp stimulation indicated that lateral incisors, canines, and first and second premolars were more anesthetized than central incisors and first molars. Conclusion: AMSA injection using the Wand method seems to avoid severe injection pain and seems to be very effective for pulpal anesthesia at lateral incisors, canines, and premolars.

Objectives: This study investigated the influence of a silica-coating method on the resin bond of two different resin composite cements to the intaglio surface of Procera AllCeram densely sintered, high-purity, alumina ceramic restorations after long-term storage and thermocycling. Method and materials: Densely sintered alumina ceramic specimens were fabricated with the intaglio surface of the Procera AllCeram coping and randomly divided into five adhesive groups (100 total specimens). Resin composite cylinders were bonded either to the untreated or to the tribochemical silica/silane-coated ceramic surface with either a conventional Bis-GMA resin cement or a resin composite containing an adhesive phosphate monomer (Panavia 21) in combination with their corresponding bonding/silane coupling agents. Panavia was also used without silanization to the untreated ceramic surface (control). Subgroups of 10 specimens were stored in distilled water for either 3 (baseline) or 180 days prior to shear bond strength testing. The 180-day samples were subjected to repeated thermocycling for a total of 12,000 cycles. Data were analyzed with one-way analysis of variance and Tukey's multiple comparison. Results: Silica coating significantly increased overall bond strength to Procera AllCeram. RelyX ARC and silica coating revealed the highest bond strength at baseline. Long-term storage and thermocycling significantly decreased overall bond strength. Two groups revealed the significantly highest bond strength values after artificial aging: Panavia 21 with its silane/bonding agent to the original ceramic surface and Panavia 21 to the silica-coated ceramic surface. Conclusion: The use of a resin composite containing an adhesive phosphate monomer either in combination with a silane coupling/bonding agent or after tribochemical silica/silane coating revealed the highest long-term shear bond strength to the intaglio surface of Procera AllCeram restorations.

There is a need to study the main and interactive bonding effects of differences in solvent and curing mode used for adhesive monomers in dentin bonding systems. Objective: Two solvents (acetone and ethanol) and curing methods (light cure, dual cure) were evaluated on their effects on bond strength and interfacial morphology. Method and materials: The adhesives studied were based on two monomers, pyromellitate of glyceryl dimethacrylate (PMGDM) and 2-hydroxy ethyl methacrylate (HEMA). Four groups of eight teeth each were cut to expose planar dentin sections and treated with (a) light-cure system with acetone as solvent (LCA group); (b) light-cure system with ethanol as solvent (LCE group); (c) dual-cure system with acetone as solvent (DCA group); and (d) dual-cure system with ethanol as solvent (DCE group). The treated sections were tested for shear bond strength to composite discs and interfacial morphology. Results: The mean (standard deviation) of shear bond strength values (MPa) for the different groups were: LCA: 11.8 (2.3); LCE: 12.7 (2.7); DCA: 24.9 (9.3); and DCE: 21.6 (9.6). All bonded sections were characterized by a similar hybrid layer, resin tags, and overall interfacial morphology. Conclusion: There was a significant difference in shear bond strength as a function of cure mode, but not of solvent. The mean bond strength was higher for dual-cure systems studied. Oxygen inhibition effects may account for the difference between light-cure and dual-cure types.