Quintessence International, 08/2011

Objective: To evaluate the long-term performance of conventionally luted In-Ceram crowns with a maximum follow-up period of 18.6 years. Method and Materials: Eighty patients (39 females and 41 males) were treated at the University of Göttingen with a total of 272 In-Ceram restorations (163 anterior and 109 posterior). All participated in a clinical followup examination (mean observational period, 13.5 ± 3.6 years). Time-dependent crown survival (in situ criteria) and success rates (event-free restorations) were calculated according to Kaplan-Meier and analyzed in relation to the crown position (anterior vs posterior crowns) using a Cox regression model. Results: Forty-three complete failures (overall survival, 80.5%) were recorded; 73.4% remained event-free after 15 years. Of the 163 anterior restorations, 18 crowns failed (9 fractures and 9 biologic reasons), resulting in a survival rate of 87.5% after 15 years (success rate, 82.7%). The remaining complete failures (10 fractures, 8 biologic reasons, and 7 changes of treatment plan) were recorded for posterior crowns (survival rate, 68.3%; success rate, 56.9%). Cox regression revealed a significant difference in survival (P = .00523) and success rates (P = .000297) of anterior and posterior crowns. Conclusion: The survival and success rates of anterior In-Ceram crowns at 15 years are comparable to those published for metal-ceramic crowns. Significantly lower survival rates and an increased rate of complications should be expected if In-Ceram crowns are placed on premolars and molars. Chipping of the veneering material was the most frequent technical complication in the posterior area. Keywords: all-ceramic, aluminous core restorations, clinical performance, retrospective study, single crowns

Objective: To compare implant stability between 1- and 2-stage Nobel Biocare TiUnite implants at various points of time after placement. Method and Materials: Thirty patients were enrolled according to specific selection criteria to 1- or 2-stage treatment. Nineteen patients received 35 1-stage early loaded implants, and 10 patients received 26 2-stage early loaded implants. A total of 32 Brånemark System MKIII Groovy and 29 NobelSpeedy Groovy implants were placed in the premolar and molar areas. Implant stability was assessed, in both groups, by means of the Osstell Mentor device at the time of implant placement and at 8 and 12 weeks. All patients were monitored from implant placement until 6 months of function. Results: One 1-stage complicated implant showed discontinuous measurements, and this patient was excluded from the analysis. In the maxilla (31 implants), there was no significant difference for implant stability quotients between the groups at any point (P > .05). In the mandible (29 implants), there was no significant difference for ISQ between the groups at baseline or 8 weeks (P > .05); however, a significant difference was found after 12 weeks (P = .0261). No implant failed between surgery and the end of the study, and there was an overall survival rate of 100%. Conclusion: High ISQ values were found in both groups at each time point. One-stage technique is a viable alternative to 2-stage technique. The utilized implants seem to be suitable for early loading in both arches. NobelSpeedy Groovy showed a higher primary anchorage, especially in the maxilla. Keywords: dental implants, implant stability, implant surface modification, implant survival, osseointegration, resonance frequency analysis

A single missing tooth in the posterior atrophic maxillary segment poses a therapeutic challenge. Open sinus lift is not often performed because of anatomical restrictions and the need for specific surgical skills. The osteotome approach has considerable efficacy and safety limitations. In many cases, the clinician elects to treat with a three-unit partial denture or discard any rehabilitation plans. Two cases in which minimal invasive antral membrane balloon elevation was performed for single-tooth replacement are presented. This procedure appears to be a relatively simple, highly effective, and safe solution for single- tooth, implant-supported restorations of the posterior atrophic maxilla. Keywords: antral membrane, bone augmentation, implants, maxilla, maxillary sinus

Objective: Assessing the level of precision entailed by the virtual fit of dental restorations is a very challenging issue. A cement space between an abutment tooth and a dental restoration is a clinical requisite that precludes the application of conventional best-fit registration protocols routinely applied in industrial precision measurements. Since two-dimensional fit assessment techniques currently used in dentistry miss important information about the third dimension, a new protocol was developed to provide threedimensional information for the virtual registration of the digitized restoration with respect to the abutment. Method and Materials: CAD/CAM was used to produce 10 titanium single crown copings for five gypsum master casts each, representing a molar prepared for a full crown. An industrial noncontact scanner was used for digitizing the components. Registration of surface data sets was achieved by a new triple-scan protocol. For statistical analysis and repeatability testing of the triple-scan protocol, mean distances of the cement space of all copings on their respective abutments were measured three times. Results: The validity of the approach is verified by intraclass correlation coefficients that revealed an almost perfect coefficient for repeatability (ICC = 0.981, P .001) with a 95% confidence range between 0.970 and 0.989. Conclusion: The triple-scan protocol represents a reliable registration approach for surface data sets in dental applications and eliminates the limitations of conventional best-fit registration protocols when a cement space or gap is present between a restoration and its underlying abutment. Future fit assessment investigations can implement this approach of obtaining detailed information of component precision in all spatial orientation. Keywords: CAD/CAM, precision, repeatability, triple scan, virtual fit assessment

Objective: Morphologic and morphometric differences in the anatomy of the temporomandibular joint (TMJ) between asymptomatic volunteers and patients with temporomandibular disorders (TMDs) were evaluated using magnetic resonance imaging (MRI). Method and Materials: Forty volunteers were examined using a 1.5-T MRI and double surface coils. Both temporomandibular joints were imaged simultaneously; 78 joints could be evaluated. Each TMJ was examined in the intercuspal position in a parasagittal plane. Images were analyzed morphometrically and morphologically and compared to data retrospectively obtained from 91 age-matched patients. Results: Considering the position of the disc morphologically, 66.7% of the volunteers had a normal disc position while 28.6% of the patients did. Anterior disc displacement with reduction was diagnosed in 33.3% of volunteers and 31.0% of the patients. Anterior disc displacement without reduction was found only in patients (19.2%). Comparison of morphometric data between patients and volunteers revealed shortening of the disc and a thickening in the intermedial part and the posterior band in patients. In patients, the disc presented anteriorly and the condyle was positioned superiorly and posteriorly in the mandibular fossa when compared to the volunteers. Therefore, the posterior and superior joint spaces were smaller in patients. Women showed disc displacement and combined morphometric changes in the TMJ structures significantly more often than men. Conclusion: A large variation of morphometric parameters in temporomandibular joints could be demonstrated. However, reduced disc length, thickening of the disc, narrowed interarticular superior and posterior distances, and a superior-posterior position of the condyle are more commonly associated with joint pathology. Keywords: craniomandibular disorders, magnetic resonance imaging, temporomandibular joint

Objective: To compare the dimensional changes of two autopolymerising denture base resins using three different processing techniques. Method and Materials: Sixty edentulous denture bases were made from the polymethylmethacrylates FuturaGen and PalaXpress. Ten bases were made from each resin using a manual injection technique (MI), a pneumatic injection technique (PI), and the fluid resin technique (F). Posterior palatal gap widths between casts and denture bases were measured. For an additional three-dimensional examination of occlusal changes, 10 maxillary dentures were made using FuturaGen/MI and 10 using PalaXpress/PI. Intermolar widths and changes in vertical dimension were determined. In all groups, measurements were taken after polymerization, after removal and repositioning, after polishing, and after storage in water for 1 and 3 weeks. Data were analyzed by using two-way ANOVA and Tukey test (P .05). Results: There were no differences in dimensional changes of FuturaGen and PalaXpress specimens. The pneumatic injection system produced significantly smaller posterior palatal gaps after storage in water for 3 weeks compared to the manual injection system (P .0005) and the fluid resin technique (P = .003). The posterior gaps of dentures were = 0.04 mm and below the recommended depth for carving a posterior palatal seal (0.4 to 3.0 mm). Conclusion: The processing technique rather than the choice of the two resins seems to be the dominate variable with respect to dimensional changes. Keywords: dentures, dimensional changes, injection system, polymethylmethacrylate, posterior palatal gap, posterior palatal seal

Objective: To evaluate the clinicopathologic features of pediatric mucoceles diagnosed in two public institutions in Brazil during an 18-year period. Method and Materials: Clinical data (age, sex, history of trauma, location, and size) of 138 cases of mucoceles in children 0 to 16 years of age were obtained from medical records. The lesions were classified as mucus extravasation phenomenon and mucus retention phenomenon, depending on the presence of epithelial lining in the microscopic analysis. Results: Mucoceles made up 24.5% of the oral pediatric lesions diagnosed in the period of study. Age at diagnosis ranged from 0.4 to 16.0 years, with a mean age of 10.8 years. Of the total of mucoceles, 87 were observed in females and 51 in males. The lower lip was the most commonly affected site, and a history of trauma was related by 87% of the patients. Histologically, 96.4% of mucoceles were diagnosed as mucus extravasation phenomenon. Cases of mucus retention phenomenon were relatively more common in the floor of the mouth, since one in three lesions in this location belonged to this histologic type. Regarding lesions in the lower lip, only 2.65% were diagnosed as mucus retention phenomenon. Conclusion: Trauma is the main etiologic factor involved in the development of mucoceles in children. The mucus extravasation phenomenon is the most common histologic type in this age group. Although rare, the retention type seems to be more common in lesions on the floor of the mouth. Keywords: minor salivary glands, mucoceles, mucus extravasation cyst, mucus retention cyst, pediatric population, ranula

Objective: To determine in vitro the action of chlorhexidine digluconate and different commercially available mouthrinses on oral microorganisms. Method and Materials: Minimal inhibitory concentrations and possible induction of resistance by chlorhexidine digluconate, an essential oil-containing mouthwash and an amine fluoride/stannous fluoride solution, were determined against microorganisms normally found in the oral cavity (10 streptococci, 2 enterobacteria, 1 Candida albicans, 8 Porphyromonas gingivalis, 6 Aggregatibacter actinomycetemcomitans, and 1 Fusobacterium nucleatum). Further, the effect of a 1-minute exposure on cell and bacterial viability was studied. Results: The susceptibility of the oral microorganisms to chlorhexidine digluconate ranged from 0.01% to 0.50%. Passages on agar plates containing subinhibitory concentrations of chlorhexidine digluconate resulted in a transitory moderate increase in the tolerance to chlorhexidine digluconate in five of the 24 isolates. After 1 minute of exposure, chlorhexidine digluconate solutions as well as the essential oil and the amine/stannous fluoride-containing solutions showed a high activity against the tested microorganisms. Commercially available chlorhexidine digluconate formulations (ie, those with antidiscoloration systems) were partly less efficient than the corresponding manually prepared chlorhexidine digluconate preparation. The determination of MTT resulted in a strong cytotoxicity of all tested preparations to gingival fibroblasts. Conclusion: The results indicate that most of the chlorhexidine digluconate formulations as well as essential oil and the amine fluoride/stannous fluoride solutions are active against oral microbes. Long-term use of these agents would not result in emergent antimicrobial resistance. Keywords: chlorhexidine, mouthrinse, periodontopathogenic bacteria

Objective: To compare the prevalence of orofacial manifestations between patients with and without sickle cell anemia and to investigate the distribution of such events in patients with sickle cell anemia by sex and age. Method and Material: A cross-sectional study was conducted in which 330 subjects divided into two groups (a group of individuals with sickle cell anemia and a healthy control group) were examined. Results: It was observed that patients with sickle cell anemia had a significantly higher prevalence of previous mental nerve neuropathy (P = .000) and delayed tooth eruption (P = .006) than patients without the disease. Regarding the distribution of orofacial manifestations in patients with sickle cell anemia by sex and age, the only statistical associations were between the prevalence of previous mental nerve neuropathy and sex (P = .023) and previous mandibular pain and age (P = .019). Conclusions: This study found that sickle cell anemia is associated with the prevalence of previous mental nerve neuropathy and delayed tooth eruption. Moreover, previous mental nerve neuropathy is more frequent among females with sickle cell anemia, and previous mandibular pain is more frequent among individuals older than 21 years of age with sickle cell anemia. Further studies using a methodology similar to the one in this study are necessary considering the scarcity of studies using this approach. Keywords: dentistry, epidemiology, sickle cell anemia

This in vitro study investigated the depth of cure of a microhybrid composite resin when cured with reduced times of exposure to three commercially available curing lights. Different sample thicknesses (1, 2, and 3 mm) were light cured in high intensity polymerization mode (2,400 mW/cm2 for 5, 10, 15, and 20 seconds; 1,100 mW/cm2 for 10, 20, 30, and 40 seconds; and 1,100 mW/cm2 for 10, 20, 30, and 40 seconds, respectively). The degree of conversion (%) at the bottom of each sample was measured by Attenuated Total Reflection Fourier Transform Infrared (ATR F-TIR) analysis after each polymerization step. Data were analyzed by ANOVA for repeated measures, showing the degree of conversion was not influenced by the curing light employed (P = .622) but was significantly influenced by the thickness of composite resin (P .05). Variations in the degree of conversion vs the shorter irradiation time permitted (T1) were not significant among different lamps but were significant among different thicknesses. The depth of cure of microhybrid composite resin appears not to be influenced by the curing light employed. Increased irradiation time significantly increases the degree of conversion. Thickness strongly influences depth of cure. Keywords: composite thickness, curing depth, F-TIR, irradiation time