Quintessence International, 09/2007

Complete prosthodontic rehabilitation using single-tooth crowns is an invasive therapy, even though the success of single-tooth crowns is well proven. In some cases, adhesively luted glass-ceramic restorations with reduced preparation depths might be a less invasive alternative. In the case presented, a 40-year-old female patient with multiple cement restorations, erosions, dysfunctional abrasion, and gap formation in the maxillary anterior region received treatment to restore function and esthetics. Minimally invasive glass-ceramic full-coverage crowns, partial crowns, and veneers were placed using the adhesive luting technique. The functional rehabilitation included increasing the occlusal height by about 2 mm. The patient was clinically followed for 4.5 years at annual examinations, which included dental and periodontal evaluations and a clinical quality assessment applying modified California Dental Association (CDA) criteria. Observations yielded only marginal discolorations and gingival recession of minor clinical importance. No adverse events occurred; the patient was highly satisfied with the esthetic result and had no complaints. Keywords: acid etching, adhesive luting, all-ceramic restorations, Celay, esthetics, functional rehabilitation, glass-ceramics, long-term success, minimally invasive preparation

The specific biomechanical alterations related to vitality loss or endodontic procedures are confusing issues for the practitioner and have been controversially approached from a clinical standpoint. The aim of part 1 of this literature review is to present an overview of the current knowledge about composition changes, structural alterations, and status following endodontic therapy and restorative procedures. The basic search process included a systematic review of the PubMed/Medline database between 1990 and 2005, using single or combined key words to obtain the most comprehensive list of references; a perusal of the references of the relevant sources completed the review. Only negligible alterations in tissue moisture and composition attributable to vitality loss or endodontic therapy were reported. Loss of vitality followed by proper endodontic therapy proved to affect tooth biomechanical behavior only to a limited extent. Conversely, tooth strength is reduced in proportion to coronal tissue loss, due to either caries lesion or restorative procedures. Therefore, the best current approach for restoring endodontically treated teeth seems to (1) minimize tissue sacrifice, especially in the cervical area so that a ferrule effect can be created, (2) use adhesive procedures at both radicular and coronal levels to strengthen remaining tooth structure and optimize restoration stability and retention, and (3) use post and core materials with physical properties close to those of natural dentin, because of the limitations of current adhesive procedures. Keywords: endodontic therapy, nonvital tooth, post and core, tooth biomechanics, tooth strength

Objective: To evaluate short- and long-term shear bond strengths of 4 luting agents to zirconia following different surface treatments. Method and Materials: A total of 320 ceramic specimens fabricated from a commercial zirconium oxide ceramic (Lava) were randomly divided into 4 groups: left untreated (NOT), airborne-particle abraded (SND), Rocatec tribochemical silica/silane coated (ROC), or ground and polished (GRD). Resin composite cylinders were bonded to the zirconia specimens with resin composite luting agent RelyX ARC (ARC), universal adhesive resin composite RelyX Unicem (UNI), adhesive-phosphate-monomer-containing resin composite Panavia F (PAN), or the hybrid glass-ionomer cement RelyX Luting (LUT). Subgroups of 10 specimens were stored in distilled water (37°C) for 3 days (ST) or stored for 180 days and thermocycled for 12,000 cycles (LT/TC) before shear bond strength was tested. Statistical analyses included Kruskal-Wallis and Wilcoxon 2-sample rank sum test (a = .01). Results: Short-term shear bond strengths were higher with ROC than with SND, which were both greater than GRD or NOT. UNI revealed higher shear bond strengths than PAN, ARC, and LUT. LT / TC significantly decreased shear bond strength values. GRD and NOT produced the lowest shear bond strengths. SND and ROC significantly increased bond strength. ROC generally yielded the highest long-term shear bond strength, especially with UNI, PAN, or ARC. These were similar to SND and PAN, which revealed the highest long-term shear bond strengths. Conclusions: Surface treatment, luting agent, and storage conditions significantly influence shear bond strengths to zirconia. Artificial aging significantly reduces shear bond strengths. Airborne-particle abrasion combined with a resin composite containing adhesive phosphate monomers or tribochemical silica / silane coating combined with any of the tested resin composite luting agents provides superior long-term shear bond strength values. Keywords: bond strength, ceramic, luting agent, surface treatment, zirconia

This article describes a new technique using 3-D computerized tomography and virtual implant planning with flapless guided surgery and placement of prefabricated, custom-milled zirconia implant abutments. After extraction of the mandibular right first and second molars and healing of the sockets, a removable prosthesis replacing these teeth was fabricated and scanned. Implant placement was planned via interactive imaging and CAD/CAM software and then placed with a CAD/CAM fabricated surgical guide, using a flapless surgical technique. Custom zirconia abutments were fabricated on an altered master cast, placed, and torqued to 35 Ncm at the time of implant surgery. Abutment positions, contours, and soft tissue marginal adaptation were in close agreement with those on the master cast. Acrylic resin provisional crowns were cemented into position and left in passive occlusion during healing. Computerized tomography and interactive planning software can be used to allow precise placement of implants and the fabrication and immediate insertion of custom-made final abutments, providing clinicians with a surgically and prosthetically efficient clinical technique. Keywords: CAD/CAM, crestal bone, custom abutment, dental implant, immediate provisionalization, osseointegration

Objective: To compare the diagnostic quality of 2-dimensional panoramic views generated from imaging data acquired by a newly developed cone beam machine with the diagnostic quality of conventional digital orthopantomograms (OPTs). Method and Materials: Thirty panoramic views reconstructed from digital volume tomograms (DVT) obtained by the pre-retail version of Galileos (Sirona Dental Systems), a newly developed compact cone beam device, were compared with 30 OPT images acquired by Orthophos XG Plus (Sirona Dental Systems). Diagnostic quality was assessed by 3 observers on criteria regarding detection of diagnosis-related findings, image quality, and visualization of anatomic structures in the maxillomandibular area. Wilcoxon rank sum test was applied for paired comparison. Results: Statistical analysis showed no significant difference in diagnostic quality between both imaging modes using a calculation model based on 10 weighted criteria (P = .629). There was especially no statistically significant difference in the assessment of diagnosis-related findings detection (P = .163). Image quality of DVT panoramic views was significantly lower than that of OPT. Except for mandibular canal and alveolar ridge gingiva, all evaluated anatomic structures were visualized better by DVT. Intraclass correlation coefficients were consistently higher in the DVT group for all criteria but 2, although the difference was not statistically significant (P = .374). Conclusions: DVT panoramic views perform better in diagnosis of specific lesions, whereas OPTs provide a better image quality for a general overview of the maxillomandibular area. The diagnostic quality of both imaging modes is, however, equal. Keywords: cone beam computerized tomography, diagnostic quality, digital radiology, digital volume tomography, image quality, maxillofacial imaging, orthopantomogram

Changing demographics and improved medical management of disease are placing increasing demands on dental providers for increased knowledge of oral manifestations of systemic disease and their dental management. The geriatric population is the most rapidly growing segment of the population and will account for 23% of the US population by 2040. These patients have specific oral changes in their teeth, periodontium, oral mucosa, salivary glands, and oral motor and sensory function related to their increasing age. In addition, these patients have complex medical disorders that affect the provision of dental care. Cardiovascular, cerebrovascular, neurologic, and pulmonary diseases represent some common medical conditions that have significant implications on how dental care is provided to geriatric patients. This article reviews age-related oral changes in older adults and provides a simple and efficient approach to the successful management of the geriatric patient. Keywords: aging, decision making, dental care, diagnosing oral problems, geriatrics, oral health, oral medicine

Variation in the normal anatomic pattern of the inferior alveolar nerve canal such as bifid or trifid mandibular nerve canal is one of the reasons for local anesthetic failure in dental practice. The present article reports 5 cases of bifid mandibular nerve canal and 1 case of trifid mandibular canal and discusses their diagnostic criteria, radiographic features, and clinical implications in dental practice. The objective of this review is to help clinicians identify bifid and trifid mandibular canals on panoramic radiographs and subsequently use the information in the modification of dental treatment planning. Once the multiple canals are identified, the local anesthetic injection technique, prosthetic design, and surgical procedures can be modified to prevent pain and discomfort during treatment procedures. Keywords: bifid mandibular canal, inferior alveolar nerve, local anesthesia, mandibular canal, panoramic radiograph, trifid mandibular canal

Objectives: To investigate the toxicity of 4 types of resin-based dental composites with different compositions and to determine the components released from them using high-performance liquid chromatography (HPLC). Method and Materials: Resin composite disks (Z100, Solitaire 2, Filtek P60, and Synergy) were prepared, and cytotoxicity was tested on Balb/C 3T3 fibroblasts. In the first part of the study, cells were exposed to the composites for 72 hours (direct method), and in the second part to ethanolic extracts of the composites for 24 hours (indirect method), both at 37°C. Cell viability was then determined by the MTT (3[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) method. Results: The dental composites and their ethanolic extracts had adverse effects on the viability of Balb/C 3T3 fibroblasts. ANOVA revealed highly significant differences in cytotoxicity between the groups (P < .001) for both the direct and indirect methods. Follow-up comparison by Tukey test (a = .05) showed that Synergy was significantly less toxic than the other resin composites and Solitaire 2 was significantly more cytotoxic when the materials were tested by the direct method. However, using the indirect method, the extract of Synergy was significantly more toxic than all the other extracts. Bis-GMA, TEGDMA, UDMA, bis-EMA, and bisphenol A were detected by HPLC analysis; however, their presence and concentrations varied from one composite to another. Conclusions: The cytotoxicity level of resin-based dental composites depends on their chemical composition, leaching medium, and the amount and type of the components that can be extracted from the materials. Keywords: cytotoxicity, leached components, resin composite

Objectives: To evaluate, at different times, the diametral tensile strength (DTS) of dual-curing resin cements that were not photopolymerized. Method and Materials: Equal amounts of base and catalyst pastes of Panavia F (Kuraray), Variolink II (Vivadent), Rely X (3M ESPE), and Enforce (Dentsply) were mixed and inserted into cylindrical molds (4 3 2 mm) (n = 10). Cements were not photopolymerized. DTS test was performed in a testing machine at 30 minutes, 1 hour, 24 hours, and 7 days. The specimens were stored in light-proof containers with distilled water at 37°C until the time of assay. An autopolymerizing resin cement (Cement-It, Jeneric Pentron) and a zinc phosphate cement served as controls. One-way analysis of variance (ANOVA) and Tukey test were performed separately for each cement and for each time (P < .05). Results: All cements showed an increase in DTS when tested at 1 and 24 hours. Tests at 24 hours and 7 days revealed no statistically significant differences. In all groups, the zinc phosphate cement had the lowest DTS mean values (2.1 MPa, 3.6 MPa, 6.5 MPa, and 6.9 MPa), while Cement-It (35.1 MPa, 33.6 MPa, 46.9 MPa, and 46.3 MPa) and Enforce (31.9 MPa, 31.7 MPa, 43.4 MPa, and 47.6 MPa) presented the highest DTS mean values. Conclusion: All cements presented maximal strength at 24 hours. The dual-curing resin cements, even when nonphotopolymerized, demonstrated higher DTS than the zinc phosphate cement and similar or lower values than the autopolymerizing resin cement. Keywords: autopolymerization, diametral tensile strength, dual-curing resin cements, mechanical properties, metallic restorations, polymerization modes

Objective: To test the efficacy of conventional radiometry with indirect digital image analysis in the assessment of the relative radiopacity of dental cements used as liners or bases compared to human enamel and dentin. Method and Materials: Disks of 15 different dental cements, 5 mm in diameter and 2 mm thick, were exposed to radiation together with 2-mm-thick disks of enamel and dentin and an aluminum step wedge. Density was evaluated by digital transmission densitometry and with the histogram function of an image analysis program following digitization of the radiographs with a flatbed scanner. Results: A higher number of dental cements were discriminated from both dentin and enamel with conventional radiographic densitometer. All the cements examined, except Ionoseal (Voco) and Ionobond (Voco), were more radiopaque than dentin. With both methods, Chelon-Silver (3M ESPE) had the highest radiopacity and glass-ionomer cements the lowest. Conclusion: Radiodensity of dental cements can be differentiated with a high probability with the conventional radiometric method. Keywords: computer-assisted densitometry, dental cements, dental radiography

Objectives: To assess the effects of exposure to 6 chemical agents on the permeability of latex gloves by dye permeability test and to qualitatively evaluate the microscopic changes in the ultrastructure of the gloves. Method and Materials: The middle fingers of 35 medium-sized, nonsterile latex gloves were used. The chemical agents tested were eugenol, 5% NaOCl, 17% EDTA, 0.2% chlorhexidine gluconate, Cresophene (Septodent), and Chlorispray (Anios). Following treatment for 15 minutes with each chemical agent, glove fingers were filled with 10 mL of 0.02% erythrosine dye solution. Then the outer glove surface was washed with 10 mL of distilled water at intervals of 15, 30, 45, and 60 minutes. A spectrophotometer was used at 530-nm wavelength to determine the percentage of absorption from each collected washing solution. The results were compared with the values obtained from untreated gloves. Additionally, small pieces of the glove samples were examined by SEM to determine whether any ultrastructural changes occurred upon exposure to the chemicals. Results: The permeability of gloves was increased by exposure to Chlorispray and Cresophene, but 5% NaOCl, 17% EDTA, and 0.2% chlorhexidine gluconate had no effect. Major surface changes were noticed in NaOCl, EDTA, Cresophene, and Chlorispray groups, while eugenol and chlorhexidine gluconate had minimal or no effect. Conclusion: Damaging effects of chemical agents on latex gloves for penetration and infection control should be considered by the dental practitioner. Keywords: chemical agents, latex gloves, permeability

Objective: To evaluate wear resistance, by weight loss and roughness changes, of resin cements and indirect restorative materials to toothbrushing and toothbrushing associated with pH-challenge simulation. Method and Materials: The following materials were studied: Enforce resin cement (Dentsply), Rely X resin cement (3M ESPE), Variolink II resin cement (Ivoclar/Vivadent), Artglass indirect resin composite (Heraeus Kulzer), and Duceram Plus porcelain (Degussa). Twenty cylindrical specimens were prepared for each material for a total of 10 groups (n = 10). After finishing and polishing, the specimens were subjected to toothbrushing. One group of each material was pH cycled before abrasion. For toothbrushing, a machine containing soft-bristle tips, dentifrice, and water was used. One hundred thousand brushing cycles were performed. Weight loss was determined as the percentage difference between initial (before brushing) and final (after brushing) measurements. Roughness changes were evaluated by the difference between initial and final measurements. Data were analyzed with the paired t test, 2-way ANOVA, and Tukey test (a=0.05). Results: Paired t test showed significant differences in weight loss and roughness after toothbrushing (P < .01). Statistically significant differences were found among materials for both weight loss, which ranged from 0.34% (Duceram Plus) to 1.85% (Enforce/pH), and roughness changes, which ranged from -0.03 µm (Duceram Plus) to 0.29 µm (Rely X/pH). Conclusions: Among cements, Variolink II exhibited the least weight loss and roughness increase. Of all materials, Duceram Plus porcelain presented the lowest weight loss and became smoother after abrasion. pH cycling had no influence on material weight or roughness changes after abrasion. Keywords: abrasion, ceramic, pH cycling, resin cements, roughness, toothbrushing

Objective: To compare, under laboratory conditions, the efficacy of different polishing systems for various light-curing restorative materials. Method and Materials: Class 5 cavities were prepared in 65 human teeth and filled with 5 different light-curing restorative materials. To increase the number of samples, an extra 585 Class 5 cavities were made in resin disks and filled with the 5 different restorative materials. All restorations were polished with 13 polishing procedures commonly used in dental practice. The restoration surfaces were evaluated micromorphologically by means of SEM. A quantitative analysis of the polishing result was performed with the surface tester with waveline profilometry. The time required to achieve a polished surface was also measured. Results: Surfaces of all 5 restorative materials showed a satisfactory finish after treatment. SEM analysis and profilometry showed good surface qualities with large smooth, homogenous areas with low roughness. All polished surfaces were smoother than natural dental enamel. Sof-Lex, Super Snap, and Bush composite finished set 5430 systems showed the best areas with a smooth and homogenous surface. The extra effort required with several systems resulted in a smooth final restoration. Conclusion: The surface produced by the carbide finisher H134Q was rough, so it is useful for effective contouring of restorations. Application of the finishers H282K and H22ALGK led to a high share in good surface quality, which could be enhanced by using polishing paste as a final working step. The instruments H22GK and the systems One Gloss and Enhance were not recommendable. In comparison, the combination of H134Q and H22ALGK was effective, at the same time preserving tissue and saving time in finishing light-cured Class 5 restorations. The use of polishing paste as a final step is recommended. Keywords: carbide finishing bur, ergometry, light-cured restorations, polishing systems

Objectives: Some patients with a temporomandibular disorder (TMD) and coexisting otologic symptoms desire to know the probability of TMD therapy improving their otologic symptoms. The aim of this study was to determine a clinically valid method for identifying which otologic symptoms have a high probability of improving as a result of satisfactory TMD symptom improvement. Method and Materials: Two hundred TMD patients with coexisting tinnitus, otalgia, dizziness, and/or vertigo were asked about their otologic symptom characteristics and associations and were given clinical tests, which were speculated to predict otologic symptom response from TMD therapy. The subjects received conservative TMD therapy in a manner thought to be most advantageous for their disorders. These potential assessment instruments were then evaluated for their ability to predict otologic symptom improvement. Results: After satisfactory TMD symptom improvement was obtained, the percent of subjects reporting significant improvement or resolution of their tinnitus, otalgia, dizziness, and vertigo was 83%, 94%, 91%, and 100%, respectively. The chi-square and Fisher exact probability tests identified significant correlations for tinnitus, otalgia, and dizziness improvement with younger age; for tinnitus and otalgia improvement with subjects who related that the otologic symptom began when the TMD symptoms began, was worse when the TMD symptoms were worse, and was related to stress; and for dizziness improvement with subjects relating more severe TMD symptoms. Conclusion: Asking TMD patients with coexisting otologic symptoms these specific questions will help practitioners identify which otologic symptoms have a high probability of benefiting from TMD therapy. Keywords: dizziness, earache, prospective study, temporomandibular joint disorder, temporomandibular joint disorder therapy, tinnitus, treatment outcome, vertigo