The International Journal of Prosthodontics, 06/2004

Background: Clinicians need quality research data to decide which dental implant should be selected for patient treatment. Aim(s)/Objective(s): To present the scientific evidence for claims of relationship between characteristics of dental implants and clinical performance. Study Design: Systematic search of promotional material and Internet sites to find claims of implant superiority related to specific characteristics of the implant, and of the dental research literature to find scientific support for the claims. Main Outcome Measures: Critical appraisal of the research documentation to establish the scientific external and internal validity as a basis for the likelihood of reported treatment outcomes as a function of implant characteristics. Results: More than 220 implant brands have been identified, produced by about 80 manufacturers. The implants are made from different materials, undergo different surface treatments and come in different shapes, lengths, widths and forms. The dentist can in theory choose among more than 2,000 implants in a given patient treatment situation. Implants made from titanium and titanium alloys appear to perform well clinically in properly surgically prepared bone, regardless of small variations of shapes and forms. Various surface treatments are currently being developed to improve the capacity of a more rapid anchorage of the implant into bone. A substantial number of claims made by different manufacturers on alleged superiority due to design characteristics are not based on sound and long-term clinical scientific research. Implants are, in some parts of the world, manufactured and sold with no demonstration of adherence to any international standards. Conclusions: The scientific literature does not provide any clear directives to claims of alleged benefits of specific morphological characteristics of dental implants.

Purpose: Realistic appraisals of time and costs are crucial for research grants and financing of clinical studies by sponsors, but little is known about the time actually needed for clinical data collection in dental studies. This survey evaluated the net time of patient contact necessary for collection and documentation of clinical data to establish an empirical base for more efficient study management and budgeting. Materials and Methods: The time needed for the clinical examination of 41 prosthodontic patients in systematic follow-up was recorded. Examination covered dental status, oral hygiene status, and quality assessment of restorations by modified CDA criteria. Completion of the case report forms, data check, and provisions for data retrieval were also included. The recorded times were analyzed to obtain empirical estimates of the time actually needed for specific examination blocks and to detect potential variables of influence. Results: Predominant time records were 5 to 10 minutes for dental status (according to status complexity) or hygiene. The time needed for CDA ranking showed a linear correlation to the number of units, approximately 1 minute each. Documentation times were similar to the total contact times of all examination blocks, between 15 and 30 minutes per patient. Conclusion: The overall time for collection and documentation of retrievable data is considerable (about 30 minutes, up to 1 hour). The data provide an empirical base for sound managing and budgeting of follow-up periods in clinical investigations, which is of major importance for the quality of clinical data, and thus for the success and value of clinical investigations.

Purpose: The purpose of the study was to investigate how cancer patients with maxillofacial defects evaluate their quality of life after prosthodontic therapy, complemented by a retrospective interview for judging the various therapy steps. The results were compared with a nontumor control group (multiple tooth extractions) and with population-based norm data. Materials and Methods: A total of 34 patients were included in the study, 17 in each group. Patients first filled in a questionnaire and then answered additional questions in a standardized interview. Results: At the time of investigation, tumor patients did not significantly differ from nontumor patients regarding global quality of life. However, tumor patients had significantly less favorable values regarding role functioning, speech, mouth opening, and dry mouth, as well as pain and swallowing. In comparison with the reference data of the German population, tumor patients had considerable deficits (> 20 points) regarding role functioning, dyspnea, and financial difficulties. Other deficits (> 10 points) became apparent in global quality of life, fatigue, insomnia, and appetite. When reflecting the course of disease and recovery, tumor patients rated the diagnosis as the most stressful event and reported that the family was most instrumental in the recovery process. Conclusion: Patients with maxillofacial defects after treatment for malignancy suffer from numerous clearly definable quality of life-related symptoms and problems, even after prosthodontic treatment. These patients need psychologic care at the time of diagnosis to alleviate the burden of the cancer diagnosis and prepare for the demanding treatment. After completion of the prosthodontic treatment, therapy options for pain or speech problems should be offered.

Purpose: Dentist-patient verbal communication is important for patient satisfaction. The aim of this study was to investigate the dentist's role in the provider-patient relationship as to verbal communication and patient satisfaction with the treatment outcome in prosthetic dentistry. The dentist-specific properties were analyzed in random coefficient modeling. Materials and Methods: Sixty-one dentist-patient pairs were followed through 61 prosthodontic treatment periods. The treatment performed was fixed prosthodontic restorations on teeth or implants. One encounter at the end of each treatment period was tape recorded. The verbal communication on the recordings was analyzed using an interaction analysis instrument. Various measures of communication were used, summarizing the variational pattern of verbal interaction. Two different aspects of the patient satisfaction concept were used as dependent variables: cure (overall patient satisfaction with prosthodontic treatment), and care (patient satisfaction with a particular dental encounter during the prosthodontic treatment period). Results: In the multilevel model for care, the dentist variance was mostly explained by the communication variables. In the cure model, there was no dentist variance. The communication patterns used by the dentists thus influenced patient satisfaction in a short-term perspective but not in an intermediate perspective. Conclusion: Patient evaluation of the care during an encounter is dependent on the dentist's verbal communication activity during the encounter, but this communication has no impact on the patient evaluation of overall prosthetic treatment outcome in the intermediate time perspective.

Purpose: In an effort to provide patients with mechanically optimized implant connectors, this study was designed to assess the relative fatigue resistance of five types of connectors for the ITI implant system: (1) standard (screw-on) abutments torqued to 35, 70, and 140 Ncm; (2) metal Octa connectors torqued to 35 Ncm; (3) ceramic Octa connectors torqued to 15 and 35 Ncm; (4) cemented cast-on abutments; and (5) an experimental screw-retained composite core. Materials and Methods: To duplicate the alternating and multivectorial intraoral loading patterns, the specimens were subjected to the rotating cantilever beam test. The implants, their connectors, and abutments were spun around their longitudinal axes while a perpendicular force was applied to the external end. The objective was to determine the force level at which 50% of the specimens would survive 106 load cycles. The mean force levels at 50% failure and their 95% confidence intervals were determined using staircase analysis. Results: The fatigue resistances of the standard (screw-on) abutment, metal Octa connector, and ceramic Octa connector torqued to 35 Ncm were within a few percent of one another. The fatigue resistance of the cemented cast-on abutment was approximately half that of the screwed connectors, and the experimental screw-retained composite core's resistance was about 30%. Increasing the preload in the standard abutments and ceramic Octa connectors increased their fatigue resistance. Conclusion: Preloaded screwed components were mechanically superior to cemented cast-on abutments and screw-retained composite buildups. For the screw-on connectors, augmenting preload (ie, torque) augmented the resistance to fatigue loading.

Purpose: A procedure for 3-D analysis of the internal fit of fixed restorations has been developed. This study tested this method for investigating the fit of all-ceramic crowns. Materials and Methods: Twelve data sets of a prepared maxillary canine were acquired by direct digitizing of the metal master die (CEREC 3 camera) and by digitizing gypsum dies after conventional impression taking (CEREC 3 scan), respectively. Using these data sets, 24 all-ceramic single crowns each were machined out of two glass-ceramics. The method is based on duplicated gypsum dies of the metal master, which were made for each crown. The space between the duplicate die and the internal surface of the respective crown was filled with a low-viscosity addition silicone. These silicone films (replicas) and their corresponding dies were digitized in the same measuring position. The internal fit was calculated and quantitatively and qualitatively analyzed. Results: The mean and maximum positive deviations were 348 µm and 986 µm (camera), respectively, and 294 µm and 830 µm (scan), respectively, for Vitablocs Mk II and 332 µm and 920 µm (camera), respectively, and 307 µm and 852 µm (scan), respectively, for ProCAD. For both systems, the deviations were highest at the edges. CEREC scan yielded significantly better internal fit accuracy compared to the CEREC camera. Conclusion: Evaluation of the internal 3-D fit using the innovative method proved to be suitable. Indirect data acquisition using impression taking showed improved internal fit compared with the direct procedure. However, the differences between the data-acquisition techniques are small compared to their absolute values.