Quintessence International, 07/2008

Implant-retained overdentures are a reliable treatment option for edentulous patients, especially when only few implants can be placed. Internationally, 2 implants are considered adequate to retain an overdenture in the edentulous mandible. However, for many patients, 2 implants can be cost-prohibitive. By means of 2 clinical cases, it is shown that the insertion of a single implant in the middle of the mandible might stabilize the prosthesis and improve the oral health quality of life and the chewing function. A ball attachment with a screw-activated matrix was used to retain the overdenture. Early clinical results are promising. However, before this method can be recommended for general clinical application, long-term clinical results are needed. Keywords: central implant, chewing function, implant-retained overdenture, quality of life

Objective: To evaluate 2 techniques for the treatment of human primary molars with necrotic pulp and bifurcation bone loss by means of radiographic examination for 48 months. Method and Materials: Fifty-one mandibular primary molars were evaluated in children ranging from 4.5 to 6.5 years of age. The teeth with necrotic pulp and bifurcation bone loss were diagnosed by radiographic examination. The teeth were divided into 2 groups: group 1 (28 teeth)-pulpotomy technique using formocresol as a temporary dressing between sessions and coronal chamber obturation with zinc oxide-eugenol cement; and group 2 (23 teeth)-pulpectomy technique with calcium hydroxide paste as a temporary dressing between sessions and root canal obturation with a dense calcium hydroxide paste. Standardized radiographs were taken immediately after the fillings were completed and after 12, 24, 36, and 48 months. The radiographs were digitized and analyzed with software that outlined and measured the bifurcation radiolucency. Results: Bifurcation radiolucency reduced significantly or repaired completely for both treatments in the first 12 months. Minor radiographic reduction of the lesion was observed from 12 to 24 months, and no significant reduction of the remaining radiolucent area was observed from 24 to 48 months after treatment. Conclusion: The 2 endodontic techniques evaluated showed similar results. The main effect of treatment on the lesion repair was obtained in the first year after treatment. Keywords: calcium hydroxide, dental pulp necrosis, dental radiography, molar, primary tooth, root canal therapy

Objective: To evaluate the influence of examiner experience on the variability of periodontal probing depth measurements obtained by conventional manual probing. Method and Materials: Thirty subjects with a diagnosis of chronic periodontitis were evaluated by an experienced examiner using an electronic probe and randomly assigned to 3 groups. Examiners with different levels of experience (undergraduate students, postgraduate students, and associate professors) evaluated each group with a manual probe. Electronic and conventional probing were repeated 45 days after cause-related periodontal therapy. Results: A total of 8,127 periodontal sites were evaluated at the baseline examination and reassessment. Agreement between methods was satisfactory at the baseline examination (kappa = 0.45; P < .001) and reassessment (kappa = 0.42; P < .001). The best agreement between electronic and manual probing at the baseline examination was obtained by the postgraduate students (kappa = 0.66) and at reassessment by the associate professors (kappa = 0.60). Undergraduate students obtained the lowest agreement values in both examinations (kappa = 0.42 and 0.11, respectively). Conclusion: Examiner experience has direct influence on the accuracy of measurements. Dental schools must evaluate if the methodology employed to teach the use of conventional manual probing is effectively qualifying their students for dental practice. Keywords: electronic probe, examiner, experience, manual probe, periodontitis

Dental twinning can result from the fusion of the developing dental germinal elements or the gemination of a single germ. In bilateral anterior and posterior dental twinning, problems such as poor esthetics, dental caries, arch-length problems, and periodontal disease often occur as a result of the irregular morphology. Several treatment methods have been described in the literature with respect to the different types and morphologic variations of twinned teeth, including endodontic, restorative, surgical, periodontal, and orthodontic treatment. This report documents the case of a young patient with an exceedingly rare phenomenon of permanent twinned teeth and multiple supernumerary teeth in both sides of the mandibular and maxillary arches, as a result of combined fusion and gemination. Keywords: fusion, gemination, supernumerary teeth, twinned teeth

Objective: To measure select physical and mechanical properties of 3 machinable ceramic materials (IPS Empress CAD, Ivoclar Vivadent; Vitablocs Mark II, Vident; Paradigm C, 3M ESPE). Method and Materials: The physical and mechanical properties tested were hardness (using Vickers hardness), flexural strength and modulus (with 3-point bending), fracture toughness (with Vickers hardness indentation), and coefficient of thermal expansion (using a thermomechanical analyzer). For each of the materials, 25 specimens were fabricated to test each property, except for coefficient of thermal expansion, where n = 5. For each tested property, data were analyzed using 1-way analysis of variance and Tukey Studentized range test (significance level = .05), when required for post hoc testing. Results: Mean Vickers hardness ranged from 511.3 (SD 8.6) for Paradigm C to 569.3 (SD 10.2) for Vitablocs Mark II. Flexural strength was greatest for IPS Empress CAD at 137.51 (SD 23.34) MPa and least for Vitablocs Mark II at 94.08 (SD 14.21) MPa. Flexural modulus ranged from 8.65 (SD 2.24) GPa (Vitablocs Mark II) to 16.10 (SD 5.94) GPa (IPS Empress CAD). IPS Empress CAD had the highest fracture toughness at 2.18 (SD 0.30) MPa•m1/2, while Vitablocs Mark II had the lowest at 1.37 (SD 0.22) MPa•m1/2. Paradigm C exhibited the highest thermal expansion coefficient at 16.87 (SD 4.37) 3 10^-6/°C, and Vitablocs Mark II had the lowest at 8.60 (SD 1.47) 3 10^-6/°C. Conclusions: The 3 ceramic materials significantly differed in all of the properties measured. Vitablocs Mark II was the hardest of the 3 materials, and IPS Empress CAD had the greatest flexure strength, flexural modulus, and fracture toughness. Keywords: CAD/CAM, ceramic, machinable, properties, strength, testing

Objective: To evaluate the flexural strength, microleakage, and degree of conversion of a microhybrid resin polymerized with argon laser and halogen lamp. Method and Materials: For both flexural test and degree of conversion analysis, 5 bar samples of composite resin were prepared and polymerized according to ISO 4049. The halogen light-curing unit was used with 500 mW/cm2 for 20 seconds and the argon laser with 250 mW for 10 and 20 seconds. Samples were stored in distilled water in a dark environment at 37°C for 24 hours. The flexural property was quantified by a 3-point loading test. For the microleakage evaluation, 60 bovine incisors were used to prepare standardized Class 5 cavities, which were restored and polished. Specimens were stored in distilled water for 24 hours at 37°C and thermocycled 500 times (6°C to 60°C). Specimens were then immersed in an aqueous solution of basic fuchsin for 24 hours. Longitudinal sections of each restoration were obtained and examined with a stereomicroscope for qualitative evaluation of microleakage. Fourier transform (FT)-Raman RFS 100/S spectrometer (Bruker) was used to analyze the degree of conversion. Results: ANOVA showed no statistically significant differences of flexural strength between the photoactivation types evaluated in the flexural study. Microleakage data were statistically analyzed by Mann-Whitney and Kruskal-Wallis tests. Enamel margins resulted in a statistically lower degree of leakage than dentin margins. No statistically significant difference was found among the 3 types of photocuring studied. ANOVA also showed no statistically significant difference in the degree of conversion among the studied groups. Conclusion: According to the methodology used in this research, the argon laser is a possible alternative for photocuring, providing the same quality of polymerization as the halogen lamp. None of the photocured units tested in this study completely eliminated microleakage. Keywords: argon laser, degree of conversion, flexural properties, halogen lamp, microleakage, polymerization, resin

Impaction of maxillary canines is a common orthodontic anomaly that causes facial and dentoalveolar system problems, both functional and esthetic. A combination of surgery and orthodontics is important in bringing impacted canines to their ideal position in the dental arch. In this case report of a 14-year-old patient with impacted right and left maxillary canines, the crowns of these teeth were surgically exposed, brackets were bonded, and light orthodontic forces were delivered for 2 years to align the teeth in the dental arch. Keywords: impacted canine, surgical-orthodontic treatment

Objective: To investigate long-term clinical effects of fissure sealing in permanent teeth with regard to sealant retention, reduction of occlusal caries, and effect on the increment of smooth surface caries. Method and Materials: The study included 360 children aged 7 to 8 years with caries-free permanent teeth. Children were divided into 4 groups, and fissure sealing was performed as follows: group 1-1 maxillary first molar and 1 mandibular first molar sealed; group 2-all first molars sealed; group 3-all molars and premolars sealed on eruption; group 4-controls, no teeth sealed. Materials used for sealing were Nuva-Seal (Caulk), Concise Brand White Sealant System (3M ESPE), and Concise Enamel Bond System (3M ESPE). Control examinations were performed over 15 years, every 6 months for 2 years and then every 12 months. Results: Complete sealant retention after 15 years was observed in 22.0% of cases, and partial retention in 35.0%. The degree of sealant retention affected the occurrence of occlusal caries in sealed teeth. Reduction in caries after 15 years was 36.0% when all first molars were sealed and 54.0% when all posterior teeth were sealed. Caries developed in 7.4% of teeth with complete sealant retention, in 15.0% of teeth with partial sealant retention, and in 31.0% of teeth with complete loss of sealant. Conclusions: The degree of sealant retention depends on the duration of observation and tooth type. The degree of caries reduction depends on the number of teeth sealed. Mean caries increment was lower in children with sealed teeth than in controls. Keywords: dental caries, occlusal caries, pit and fissure sealant, sealant retention

Objective: To investigate the effect of the accelerated aging process on the color stability of feldspathic ceramic treated with dual ion exchange, overglaze, polishing, and autoglaze surface treatments. Method and Materials: A total of 40 disks (15 mm in diameter and 2 mm thick) of feldspathic ceramic were made in an A2 shade according to the manufacturer's recommendations. The samples were randomly divided into 4 groups: dual ion exchange, overglaze, polishing, and autoglaze. The samples were subjected to conditions in an accelerated aging machine for 150 and 300 hours. Differences in color before and after accelerated aging were calculated using spectrophotometric analyses. Overall color difference (ΔE) was determined using the CIE L*a*b* system for measuring small color differences. Scanning electron microscopy was used to evaluate the surface texture of samples. Color difference data were evaluated statistically by Kruskal-Wallis and Mann-Whitney U tests, with a significance level of .05. Results: After 150 and 300 hours of accelerated aging, color changes of the 4 surface treatment groups ranged between 0.35 and 1.31 ΔE units. All ΔE values were below a quantitative level that would be considered clinically acceptable. Autoglazed samples were the most color stable, followed by ion exchanged, overglazed, and polished test samples. Conclusions: All groups demonstrated color stability below a quantitative level that would be considered clinically acceptable, but long-term clinical studies are necessary to verify these findings. Keywords: aging, ceramics, color change

Oral focal mucinosis is an uncommon clinicopathologic condition that is considered the oral counterpart of cutaneous focal mucinosis. It is a disease of unknown etiology where the connective tissue undergoes a focal myxoid degeneration. A literature review disclosed 47 published cases of oral focal mucinosis. An additional case is presented; the clinical and histologic differential diagnosis, sex, age, location, treatment, and recurrence are discussed. Keywords: focal mucinosis, gingival neoplasms, myxoid lesions, oral pathology