The International Journal of Prosthodontics, 05/2004

Purpose: This study described oral health-related quality of life (OHRQoL) before and after treatment in patients with fixed, removable, and complete dentures. Materials and Methods: OHRQoL was measured using the German version of the Oral Health Impact Profile (OHIP-G) in a convenience sample of 107 prosthodontic patients at baseline and 1 and 6 to 12 months after treatment. The sum of OHIP-G item responses (OHIP-G49, range 0 to 196) characterized OHRQoL impairment in 42 patients treated with fixed prosthodontics, 31 patients treated with removable dentures, and 34 patients treated with complete dentures. OHIP-G49 medians were compared with the OHRQoL level in a general population sample (n = 2,026). A multivariable binomial regression analysis, controlling for the effects of baseline OHRQoL and follow-up wave, was used to compare the level of impaired OHRQoL in different prosthodontic treatment groups at follow-ups. Results: OHRQoL improved in 96% of the subjects. OHIP-G49 medians reached the level of OHRQoL in the general population 1 month after treatment (fixed prosthodontics patients 6 OHIP-G units; general population subjects 5 units; removable denture patients 23 units, 15 units in general population subjects; complete denture patients 13 units, 23 units in general population subjects). OHIP-G49 medians were below population norms 6 to 12 months after treatment. In patients treated with removable/complete dentures, the expected posttreatment OHIP-G49 problem rate was 1.9 times the problem rate in patients treated with fixed prosthodontics, holding baseline OHIP-G49 and follow-up wave constant. Conclusion: OHRQoL changed substantially comparing pretreatment scores with 1 and 6 to 12 months of follow-up in patients treated with fixed, removable, and complete dentures.

Purpose: The present study investigated the residual functional constraints as well as the psychosocial rehabilitation of tumor patients following prosthetic treatment with implant-supported dentures. Materials and Methods: A clinical examination and semistructured interview were performed in 66 of 132 consecutive patients who underwent tumor resection and subsequent implant-supported restoration between 1985 and 1997. Results: Functional and psychosocial constraints were improved by between 91% (general comfort) and 47% (social reintegration) of all cases, but these constraints were never fully compensated for. Restrictions in tongue mobility, loss of sensation, and radiotherapy-induced hyposalivation led to problems in chewing and swallowing, which were hardly improved by prosthetic rehabilitation. The best subjective assessments referred to appearance, followed by masticatory improvement and denture retention. Conclusion: Functional impairment cannot be fully compensated by implant-supported prosthodontic reconstructions, but such treatment contributes essentially to general well-being and relief of disease-related social restrictions.

Purpose: Occlusal transducer foils using piezoelectricity or pressure-dependent electric resistance are potential candidates for a measurement system for both absolute levels and changes in bite force. This preliminary in vitro study evaluated the possible usefulness of such transducer foils in the assessment of occlusal forces in centric occlusion. Materials and Methods: Piezoelectric force transducer foils 33 µm thick were placed between pairs of teeth with the dentition in centric occlusion. Occlusal forces were recorded in five patients, who were instructed to bite as hard as possible for about 1 second. Acrylic resin casts of each pair of antagonistic teeth were aligned with the help of interocclusal records. The casts were mounted in a jig, where a defined load could be applied. The ratio of applied force and measured sensor signal permitted a set of calibration factors. Results: A correction factor for each pair of teeth helped determine the ratio by which measured occlusal force exceeded actual tooth load. Differences in occlusal morphology gave rise to a wide span of correction factors (1.01 to 2.80). Steep cusp angles resulted in a wedge action that gave rise to a strong increase in occlusal forces, which were about twice as high as actual tooth load, with wide variation. Conclusion: This method of bite force measurement eliminated the influence of occlusal morphology by individual correction for each pair of opposing teeth. To measure the absolute load of antagonistic teeth with thin film transducer foils, one must take into account individual occlusal morphology. Forces measured with the films are a function of both actual tooth load and occlusal morphology.

Purpose: This study retrospectively evaluated zirconium oxide posts with either direct resin composite cores or indirect glass-ceramic cores after several years of clinical service. Materials and Methods: One hundred forty-five endodontically treated teeth in 88 patients were restored with zirconium oxide posts; 87 teeth were restored with direct composite cores, and 58 were restored with Empress cores prior to crowning. Seventy-nine posts with direct composite cores in 52 patients and 34 posts with glass-ceramic cores in 19 patients were reevaluated clinically and radiographically after a mean clinical service of 57.7 months and 46.3 months, respectively. Results: Periodontal probing depths remained on a healthy clinical level, and esthetics were judged excellent for the majority of teeth in both groups. In the group with direct composite cores, no failures were observed in the 79 posts that were reevaluated. In the group with indirect glass-ceramic cores, three failures were observed after 42, 43, and 55 months of clinical service. All failures were due to loss of retention. In a best-case scenario posts that could not be reevaluated were considered successful, and in a worst-case scenario they were considered failures; respective success rates were 100% and 91% in the direct group and 95% and 53% in the indirect group. Conclusion: The observed clinical success of zirconium oxide posts with direct composite cores suggests that this method of post-and-core reconstruction is clinically promising. Zirconium oxide posts with indirect glass-ceramic cores displayed a significantly higher failure rate and a high dropout rate that precludes valid conclusions.

Purpose: This study investigated the effect of different cements on microleakage and marginal adaptation of porcelain crowns. Materials and Methods: Eighty extracted molars were divided into two groups. Teeth in one group were prepared to receive Procera AllCeram crowns, whereas the other group was prepared to receive metal-ceramic crowns. Copings were made following standard techniques, and groups were divided for cementation with zinc phosphate, glass-ionomer, resin-modified glass-ionomer, or resin cement. Specimens were subjected to thermocycling prior to microleakage testing, then sectioned. Microleakage was scored using a five-point scale; marginal adaptation was assessed with a traveling microscope. Results: A significant association was found between cement type and degree of microleakage. With zinc phosphate, 76% of Procera AllCeram and 90% of metal-ceramic copings exhibited extensive microleakage. With glass-ionomer, 49% of Procera AllCeram and 66% of metal-ceramic copings had 0 microleakage scores; with resin-modified glass-ionomer, 10% of Procera AllCeram and 84% of metal-ceramic copings had 0 microleakage scores. With resin cement, 34% of Procera AllCeram and 96% of metal-ceramic copings exhibited 0 microleakage. Procera AllCeram copings had a significantly larger mean marginal gap (54 µm) compared to metal ceramic (29 µm). Conclusion: In both types of crowns, the use of resin cement resulted in the highest percentage of 0 microleakage scores, whereas the zinc phosphate cement resulted in the highest percentage of extensive microleakage.

Purpose: This article reviews the topographic and chemical properties of different oral implant surfaces and in vivo responses to them. Materials and Methods: The article considers detailed mechanical, topographic, and physical characteristics of implant surfaces. Anchorage mechanisms such as biomechanical and biochemical bonding are examined. Osteoattraction and doped surfaces are discussed. Results: Surface quality of an oral implant may be subdivided into mechanical, topographic, and physicochemical properties. Topographic properties are evaluated at the micrometer level of resolution. Moderately rough surfaces (S_a between 1.0 and 2.0 µm) show stronger bone responses than smoother or rougher surfaces. The majority of currently marketed implants are moderately rough. Oral implants permit bone ingrowth into minor surface irregularities-biomechanical bonding or osseointegration. Additional biochemical bonding seems possible with certain surfaces. Osteoattraction is a commercial term without precise biologic correspondence. Surfaces doped with biochemical agents such as bone growth factors have been developed. Conclusion: Moderately roughened surfaces seem to have some clinical advantages over smoother or rougher surfaces, but the differences are small and often not statistically significant. Bioactive implants may offer some promise.

Purpose: This article reviews clinical knowledge of selected oral implant surfaces. Materials and Methods: The surfaces most commonly used in clinical practice, marketed by the five largest oral implant companies, are identified; their clinical documentation was scrutinized following a strict protocol. Experimental knowledge of the surfaces is briefly summarized. Retrospective, prospective, and comparative clinical studies were analyzed separately, as were studies of implants in conjunction with bone grafts. Results: TiUnite anodized surfaces are clinically documented in 1- to 2-year follow-up studies at best, with failures at about 3%. Sandblasted and acid-etched SLA surfaces are documented with good clinical results for up to 3 years. Osseotite dual acid-etched implants are documented with good clinical results for up to 5 years. Frialit-2 sandblasted and etched implants are positively documented for about 3 years in one study only. The Tioblast implant is the only design documented for survival over 10 years of follow-up and success over 7 years of follow-up. Conclusion: Generally, oral implants are introduced clinically without adequate clinical documentation. Implant companies initiate clinical documentation after product launch. The standards of clinical reporting have improved over the years. Proper long-term reports have been published for only one surface, Tioblast.

Purpose: The aim of this follow-up investigation was to assess the influence of clinical variables after implant prosthodontic rehabilitation in patients without temporomandibular disorders on alterations of condylar morphology as seen radiographically. Materials and Methods: In 167 patients, the condylar findings of flattening, erosion, osteophytes, and sclerosis were scored according to severity on rotational panoramic radiographs. Findings were followed up on images taken before and on average 5 years after implant prosthodontic rehabilitation. Changes were analyzed in relation to age, gender, initial radiologic status, and occlusal support pre- and posttreatment, according to Eichner groups, by logistic regression analysis. Results: The majority of patients did not show structural alterations over the follow-up period, regardless of whether the condyle was already affected at the outset of the investigation. Condyles unaffected at the time of the first radiograph made up the majority of increases in radiographic score. Flattening and sclerosis were cumulative, whereas erosions and osteophytes had a more transient character. There was no influence of the mentioned clinical or radiographic findings on the development of changes. Conclusion: Over the investigated period, the incidence of all four noted findings doubled. However, the statistical methods employed could not detect any influence of patient variables or the insertion of implant-retained prosthodontics on the development of condylar changes in this specific patient group. Both assertions reflect the complexity of the topic.

Purpose: This study evaluated the influence of fatigue loading on the performance of an adhesive and a nonadhesive cement for cast post-and-core restorations in maxillary premolars. Materials and Methods: The adhesive cement used was Panavia 21, a resin-based composite cement, and the nonadhesive cement was PhosphaCem/C, a zinc-oxy-phosphate cement. The coronal sections of single-rooted human maxillary premolars were removed at the level of the proximal CEJ. After endodontic treatment, a cast post and core was prepared for each tooth and cemented into the root canal with either Panavia 21 (n = 8) or PhosphaCem/C (n = 8). Half of the specimens from each cement group were exposed to fatigue loading almost perpendicular to the axial axis; the other half were used as controls. Three parallel transverse root sections were cut from each specimen and used for evaluation of the influence of fatigue loading. For each section, cement integrity was studied by SEM, and retention strength of the cemented post section was determined with a push-out test. Results: For SEM evaluation and the push-out test, Panavia 21 proved significantly better than PhosphaCem/C. However, fatigue loading did not show any effect. Conclusion: Under the conditions of this study, fatiguing of cemented cast post-and-core restorations was not decisive as a single test to evaluate the quality of the cement.

Purpose: The precision of a computer-aided design/manufacturing (CAD/CAM) system to manufacture zirconium dioxide copings with a predetermined internal space was investigated. Materials and Methods: Two master models were produced in acrylic resin. One was directly scanned by the Decim Reader. The Decim Producer then manufactured 10 copings from prefabricated zirconium dioxide blocks. Five copings were prepared, aiming for an internal space to the master of 45 µm. The other five copings were prepared for an internal space of 90 µm. The second test model was used to try in the copings produced. The obtained internal space of the ceramic copings was evaluated by separate measurements of the master models and inner surfaces of the copings. The master models were measured at predetermined points with an optical instrument. The zirconium dioxide copings were measured with a contact instrument at the corresponding sites measured in the masters. Results: The first group of copings had a mean internal space to the scanned master of 41 µm and of 53 µm to the try-in master. In general, the internal space along the axial walls of the masters was smaller than that along the occlusal walls. The second group had a mean internal space of 82 µm to the scanned master and of 90 µm to the try-in master. Conclusion: The aimed-for internal space of the copings was achieved by the manufacturer. The CAD/CAM technique tested provided high precision in the manufacture of zirconium dioxide copings.

Purpose: The purpose of this study was to introduce a computer-assisted quantitative tooth wear-analyzing system and test its accuracy and precision. Materials and Methods: An image of a horizontally projected dental arch was captured, and the facet area of each tooth was calculated using a digital image analyzer. For normalization, the facet area of the individual tooth was divided by the total area of the corresponding tooth; this result was the tooth wear score. The accuracy and precision of this method were determined through the intraclass correlation coefficient using 10 dental casts. Tooth wear on the dental casts of 50 subjects was actually measured. Results: The accuracy of the tooth wear score determined by a newly trained examiner was greater than 0.85 of the intraclass correlation coefficient; this was tested against the score determined by consensus of three experienced examiners. The reproducibility within a 1-week interval was also greater than 0.85. With regard to the tooth wear score from 50 sets of dental casts, the distribution of tooth wear was generally consistent with data reported in the literature. Conclusion: The results suggest that the newly trained examiner can exhibit adequate accuracy and precision after appropriate training in identifying tooth wear facets. Recorded data from 50 subjects added face validity to this new system.

Purpose: This study examined the effect of gingival sulcular width, in the presence of an undercut, on the accuracy of dies poured from impressions made with different impression materials. Materials and Methods: Three polyvinyl siloxanes (Examix, Elite, and Express), one polyether (Permadyne), and one polysulfide (Permlastic) were used to make impressions of six metal dies. The dies were machined to simulate teeth with a chamfer preparation, root convergence, and sulci of varying widths (0.10 to 0.40 mm). The impressions were poured with type IV stone, and the resulting dies were measured under a traveling microscope at the level of the finish line. The distortion of each die was calculated. Results: The distortion ranged from 0.01% to 0.89%. All materials showed similar behavior: At the narrowest sulcular width (0.10 mm), the distortion was considerably larger (0.43% to 0.89%) than at the wider sulci (up to 0.20% in most cases). Examix (polyvinyl siloxane), Permlastic (polysulfide), and Permadyne (polyether) gave the most accurate dies for sulci 0.15 mm and wider. Express (polyvinyl siloxane) showed greater deformation than other materials in most sulcular widths under the conditions of this study. Conclusion: Accurate impressions can be expected in sulci > 0.15 mm in width at the level of the finish line coronal to an undercut. Impressions with 0.10-mm sulci widths are not predictable. The physical properties of the impression materials used cannot be anticipated based on their chemical group.