Quintessence International, 09/2005

Tooth loss due to trauma or periodontal disease is often associated with extensive deficiencies of the supporting hard and soft tissues and atrophy of the alveolar ridges. The functional and esthetic predictability of an implant-supported prosthetic restoration in patients with extensive tissue augmentation is guarded, even when lost tissues were restored at an early stage by local ridge augmentation. The prosthetic reconstruction of major tissue defects is especially difficult, as lost structures of the alveolar ridge must be replaced by the restoration, which is expected to provide optimal function and esthetics, yet allow for optimal oral hygiene. This article presents prosthetic solutions for replacing missing hard and soft tissues with implant-supported fixed and removable restorations in cases of severe tissue deficiencies. Keywords: atrophy of alveolar ridge, implants, implant-supported restorations, treatment options

Objectives: The aim of this study was to determine the caries-protective effect of 3 different desensitizing agents (Seal & Protect 2.0, D/Sense 2, and Gluma Desensitizer) on root dentin in vitro. Method and materials: The root surfaces of 60 freshly extracted, caries-free human molars were used. After removing the cementum, the teeth were coated with an acid-resistant nail varnish, exposing 2 rectangular windows of 2 X 3 mm each on the root surface. One window served as an untreated control, and the other window was treated with 1 of the desensitizing agents. The specimens were randomly distributed among the following experimental groups: group A, D/Sense 2; group B, Seal & Protect 2.0; and group C, Gluma Desensitizer. Subsequently, all specimens were demineralized for 14 days with acidified gel (HEC, pH 4.8, 37°C). Two dentinal slabs were cut from each window. The slabs were ground to a thickness of 80 µm and immersed in water. The demineralization depth was determined using a polarized light microscope. Results: The nontreated control specimens showed lesions with a mean depth of 84.9 µm (± 6.0). In the specimens treated with the desensitizing agents, lesion depth was generally significantly reduced. Statistical analysis revealed significantly lower values for the specimens in group B in comparison with the others. Conclusion: Within the limitations of an in vitro investigation, it can be concluded that the demineralization of the root surface can be hampered by applying the desensitizing agents tested. Keywords: caries prevention, demineralization, dentin, dentin sensitivity, desensitizing agents, root caries

Objectives: The aim of this study was to compare the interaction of dentin with 2 different self-etch resin bonding systems, as well as with a total-etch resin bonding system. Method and materials: Nine recently extracted, unerupted third molars, roots, and occlusal thirds were used. A standardized smear layer was produced on the occlusal dentin surface exposed. The specimens were split into 3 groups of 3 specimens each, 1 group for each bonding agent: Clearfil Liner Bond 2, Prime & Bond 2.1, and Scotchbond Multipurpose (control group). After the tooth was briefly sprayed with an air/water mixture, 1 of the experimental adhesive systems was applied on the dentin surface. A 2-mm layer of composite was applied over the adhesive system layer. After 7 days in distilled water at 37°C, the specimens were cross-sectioned perpendicular to the resin-dentin interface. The cross-sections were mounted on aluminum stubs, etched with 2% hydrochloridric acid, and studied using scanning electron microscopy. A descriptive analysis of the images of the interdiffusion zone characteristics was done first. Afterwards, statistical analyses of the measurements of the interdiffusion zone structures-hybrid layer thickness, resin tags penetration, and adhesive layer thickness using analysis of variance, followed by "post hoc" test-were carried out to compare the bonding systems' interactions. Results: The descriptive analysis of the self-etch bonding systems studied showed a good interlocking of Clearfil Liner Bond 2 with dentin, similar to Scotchbond Multipurpose and better than Prime & Bond 2.1. The analysis of variance, followed by the "post hoc" test, identified statistical differences just for the adhesive layer thickness that was thicker for Scotchbond than for Prime & Bond (P = .020). The "post hoc" test also showed a strong tendency to identify differences between the Scotchbond and the Prime & Bond groups (P = .062), and the Clearfil and the Prime & Bond groups (P = .069). Conclusion: Within the limitations of this study, Clearfil Liner Bond 2 produced the thickest hybrid layer with deepest tag formation and good interlocking with dentin, similar to the control. Statistical differences among the interdiffusion zone of the 3 bonding systems studied were identified just for the adhesive layer thickness, which was thicker for Scotchbond than for Prime & Bond. Keywords: adhesion on dentin, hybrid layer, interdiffusion zone, scanning electron microscopy, self-etch resin bonding systems

This paper presents a review of dentinogenesis imperfecta occurring in patients with osteogenesis imperfecta. The systemic manifestations and the oral aspects of dentinogenesis imperfecta in osteogenesis imperfecta are discussed, and an illustrative case is described. Keywords: case report, dental anomalies, dentinogenesis, dentinogenesis imperfecta, human dentin, osteogenesis imperfecta

Objective: Various studies have shown that the root surface condition may play an important role in wound healing. Root surface demineralization has been shown to promote the establishment of new connective tissue attachment. Various agents, including citric acid, ethylenediaminetetraacetic acid (EDTA), and tetracycline, have been used to try to achieve a root surface that is biocompatible with the adjacent periodontal cells. Traditional in vitro studies have used periodontal ligament fibroblasts and scanning electron microscopic studies to check the efficacy of these root-conditioning agents. The objective of this study was to assess the efficacy of trypan blue to evaluate fibroblast attachment in an in vitro model using V79 fibroblasts (embryonic Chinese hamster lung fibroblasts) on root specimens treated by citric acid, EDTA, and tetracycline. Method and materials: Citric acid-, EDTA-, and tetracycline-treated root specimens were placed in cultures of V79 cells and in human periodontal ligament cells, which acted as a control. The treated root specimens were removed from the cultures after 4 weeks and immediately treated with 1% trypan blue. Trypan blue was selected because it can stain only nonvital tissues. Results: The root specimens placed in V79 and human periodontal ligament cultures showed unstained areas, indicating the presence of vital cells, in contrast to the stained areas, which represented the areas devoid of cells. Conclusion: This in vitro screening model based on the trypan blue exclusion principle may be used for immediate evaluation of the efficacy of various root-conditioning agents. V79 cells may be used as an alternative to human periodontal ligament fibroblasts in the evaluation of the efficacy of root conditioning agents. Keywords: periodontal ligament fibroblasts, root conditioning, trypan blue exclusion principle, trypan blue stain, V79 cells

Objective: A survival analysis was conducted on 101 patients with oral cancer to determine the influence of certain clinical and pathological parameters on survival. Methods: Kaplan-Meier analysis and Cox proportional hazard models were used to assess survival and estimate hazard ratios adjusted for potential confounders. Results: Survival rates were influenced by tumor diameter (P = .030), clinical T (P = .028), clinical N (P = .019), clinical stage (P = .006), lymph node involvement (P = .003) and histologic malignancy grade (P = .0063). The multivariate analysis included only 1 variable, the lymph node involvement. For clinical stage, the mean histologic malignancy grade was 1.71, 2.27, 2.53, and 2.61, respectively, for stages I through IV (rs = 0.423, P .001). Conclusion: This study proposes considering the tumor size as the most significant clinical variable for predicting the survival of oral cancer patients at the time of diagnosis and the degree of lymph node involvement after the treatment. Keywords: neck dissection, oral cancer, prognosis factors, survival analysis

Objective: The aim of this study was to determine the distribution patterns of sealer relative to the gutta-percha and the canal wall following the use of different obturation techniques: vertical condensation, Obtura II, System B, SimpliFill, and Thermafil Plus; lateral condensation was used as a comparison. Methods and Materials: One hundred five extracted single-rooted teeth were divided into 5 groups of 20 according to obturation technique, with 5 in the lateral condensation group. Instrumentation technique and sealer selection were based on the manufacturer's recommendations. Following obturation, teeth were stored for 4 months at 37˚C in 100% humidity. Roots were split longitudinally and halves were examined under a stereomicroscope (310) to determine the amount of sealer coverage between the gutta-percha and canal wall. Coverage was categorized as slight (0 to 1/3), low partial (1/3 to 2/3), high partial (2/3 to 9/10), and complete (9/10 to 10/10). Results: Different techniques showed different patterns, but no obturation technique had sealer forming a continuous layer between the gutta-percha and canal wall. The vertical condensation group generally had low partial coverage. Obtura II was the only group to have slight coverage, which occurred in the coronal half. Coronal and apical halves in both the System B and Thermafil Plus groups had the most samples with high partial coverage. SimpliFill had the most samples with complete coverage in both the coronal and the apical portions. All lateral condensation samples showed low partial coverage. Conclusion: Sealer distribution patterns were incomplete and inconsistent, regardless of the obturation technique. No technique had sealer forming a continuous layer between the gutta-percha and canal wall. Keywords: obturation, root canal treatment, sealer

The purpose of this study was to determine dental and skeletal effects of compressed nickel-titanium coil springs used for distal movement of the maxillary molars. Initial and follow-up cephalometric radiographs were taken of 8 patients (2 males and 6 females) in the late mixed or permanent dentition stage with Class II malocclusion. Nickel-titanium coil springs exerting a near constant force of approximately 250 g were compressed against the maxillary molar tubes by Gurin locks. The mean treatment time was 6.95 ± 0.2 months. Dental and skeletal changes were determined as follows: The mean maxillary first molar distalization was 5.44 mm (right) and 3.75 mm (left), with a mesial tipping of 11.56 degrees (right) and 11.34 degrees (left). Anchorage loss occurred as defined by mesial movement of the first premolars and proclination of the central incisors. Vertical dental and skeletal dimensions were not affected. Keywords: anchorage loss, Class II malocclusion, distilization, intraoral, molar movement, nickel-titanium coil springs

Objective: The prognosis of endodontically treated teeth depends not only on the success of the endodontic treatment, but also on the type of reconstruction. These considerations include the decision of whether or not to use posts. Methods and materials: A literature review has been performed to create guidelines for the reconstruction of endodontically treated teeth by posts and cores. Results: Posts should only be used for the retention of core material in cases where little dental substance remains, ie, one or no cavity walls. A ferrule of 2 mm has to be provided, by surgical means if necessary. The post length is limited by the necessary apical seal of 4 to 6 mm. In cases of short posts, adhesive fixation is preferred. Ceramic posts show a higher risk of fracture than fiber posts which are retrievable. Composites have proven to be a good core material. Posts should be inserted if endodontically treated teeth are used as abutments for removable partial dentures. Conclusion: These guidelines are based mainly on in vitro studies with an evidence level of II a or II b, as there is a lack of randomized clinical studies available. The remaining tooth structure is an important factor influencing the indication of posts and cores, yet it is not sufficiently recognized in clinical studies and in vitro. Therefore, further prospective clinical studies are needed. Keywords: endodontically treated teeth, post and core, reconstruction, review