The International Journal of Prosthodontics, 02/2010

Purpose: The mandibular implant overdenture is a popular treatment modality and is well documented in the literature. Follow-up studies with a long observation period are difficult to perform due to the increasing age of patients. The present data summarize a long-term clinical observation of patients with implant overdentures. Materials and Methods: Between 1984 and 1997, edentulous patients were consecutively admitted for treatment with an implant overdenture. The dentures were connected to the implants by means of bars or ball anchors. Regular maintenance was provided with at least one or two scheduled visits per year. Recall attendance and reasons for dropout were analyzed based on the specific history of the patient. Denture maintenance service, relining, repair, and fabrication of new dentures were identified, and complications with the retention devices specified separately. Results: In the time period from 1984 to 2008, 147 patients with a total of 314 implants had completed a follow-up period of > 10 years. One hundred one patients were still available in 2008, while 46 patients were not reexamined for various reasons. Compliance was high, with a regular recall attendance of > 90%. More than 80% of dentures remained in continuous service. Although major prosthetic maintenance was rather low in relation to the long observation period, visits to a dental hygienist and dentist resulted in an annual visit rate of 1.5 and 2.4, respectively. If new dentures became necessary, these were made in student courses, which increased the treatment time and number of appointments needed. Complications with the retention devices consisted mostly of the mounting of new female retainers, the repair of bars, and the changing of ball anchors. The average number of events and the rate of prosthetic service with ball anchors were significantly higher than those with bars. Twenty-two patients changed from ball anchors to bars; 9 patients switched from a clip bar to a rigid U-shaped bar. Conclusions: This long-term follow-up study demonstrates that implant overdentures are a favorable solution for edentulous patients with regular maintenance. In spite of specific circumstances in an aging population, it is possible to provide long-term care, resulting in a good prognosis and low risk for this treatment modality. For various reasons the dropout rate can be considerable in elderly patients and prosthetic service must be provided regularly.

Purpose: The aim of this research was to provide a classification for patients with oligodontia that could act as an aid in treatment planning. Materials and Methods: Panoramic radiograph records of 70 patients with oligodontia were used to categorize the extent of the disability and treatment modality. Patients were classified into types 1 through 3 depending on the number of missing primary and permanent teeth, as well as in relation to their prosthodontic requirements. The radiographs were then assessed independently on two separate occasions by three experienced clinicians to validate the classification. Results: There was a high level of intrarater consistency in allocating patients into the three different types with a Kappa (κ) score of 0.77 for clinician 1, 0.87 for clinician 2, and 0.94 for clinician 3. There was also a strong interrater agreement (overall κ score: 0.88). A κ score greater then 0.6 is regarded as being good and greater than 0.8 as being very good. Conclusions: Oligodontia is a heterogenous condition. Patients with oligodontia can be classified as having three different types according to the extent of their disability and the complexity of their prosthodontic requirements. This classification is a reliable diagnostic tool based on the positive outcome of the inter- and intrarater consistency.

This prospective clinical trial sought to evaluate the 3-year clinical results of anterior teeth restored with 0.3-mm-thick zirconia copings and feather-edged marginal preparations. Ten patients received 19 single-tooth restorations in the anterior maxilla to restore severely decayed teeth. After a mean observation period of 39.2 months, no material fracture occured and all crowns had acceptable surfaces. A survival and success rate of 100% was recorded, which suggests that the clinical method may be a reliable treatment modality for restoring severely compromised anterior teeth.

Purpose: The aim of this study was to investigate the effect of an acrylic-based resilient liner (ARL) on perceived chewing ability in patients using mandibular complete dentures compared with that of patients using mandibular complete dentures with a conventional acrylic resin (CAR). Materials and Methods: This randomized controlled trial was conducted at two centers from April 2004 to July 2006. Seventy-four subjects were randomly allocated to either the ARL or CAR group using a random permuted block method after obtaining written informed consent. A valid questionnaire listing 35 foods was used to evaluate the subjects' perceived chewing ability of each item, assessed according to the following scale: 0 = cannot eat, 1 = can eat with difficulty, and 2 = can eat easily. If subjects did not eat the food because they disliked it or had not eaten it since first wearing dentures, they filled in a triangle or square, respectively. These figures were treated as a 0 during analysis. Results: No significant differences were observed between the ARL and CAR groups. The perceived chewing ability of subjects with new complete dentures was significantly higher than that of those with their old complete dentures. The duration of edentulism was positively associated with perceived chewing ability. Conclusions: An ARL applied to mandibular complete dentures has no significant impact on the perceived chewing ability of edentulous patients in comparison to a CAR.

Purpose: Mandibular two-implant overdentures opposing conventional complete maxillary dentures have been proposed as the standard for complete denture service. Monitoring marginal bone loss around implants is regarded as the most important criterion in determining the success of implants. The aim of this systematic literature review was to critically evaluate the literature on short- and long-term marginal bone loss associated with mandibular two-implant overdentures using different loading protocols. Materials and Methods: The MEDLINE, EMBASE, and PubMed (using medical subject headings) databases were searched using the restriction of articles in English only. Other articles were identified from the reference lists of the articles found, as well as from early online articles. Reviewed studies were those on two oral implants supporting mandibular overdentures with different loading protocols. Marginal bone loss was evaluated as well as the validity of using marginal bone loss measurements for determining the success of implants. Results: Twenty-five studies met the review criteria. Clinical studies involving conventional loading showed longterm results; however, early and immediate loading protocols were only in the short term. High success or survival rates of two implants supporting mandibular overdentures were reported, regardless of the loading protocol. A lack of standardization was revealed in the radiographic methods used for measuring marginal bone loss and the success criteria on which results were based. Long-term outcomes of the effect of different loading protocols on marginal bone loss were not found. Due to the wide methodologic variation among the included studies, it was difficult to compare data between studies or to determine long-term marginal bone loss patterns with this treatment. For conventional two-stage and one-stage loading protocols, the range of marginal bone loss seen in the first year was 0.2 to 0.7 mm and 0.0 to 2.0 mm, respectively. For early loading protocols, the range was 0.0 to 0.2 mm; immediate loading protocols saw a marginal bone loss of around 0.7 mm in the first year. Conclusions: Short-term findings indicate that so far, there is no detrimental effect on marginal bone levels with early and immediate loading protocols. However, to recommend these protocols in the long-term for two implants supporting mandibular overdentures may be premature.

The purpose of this study was to investigate the relationship between chewing ability and diet among elderly edentulous patients whose dentures were funded by the Department of Health in Kaohsiung City, Taiwan. A cluster sample of 103 elderly edentulous subjects 65 years and older (68 men, 35 women) was gathered randomly and assessed through use of a questionnaire. The responses to queries regarding demographics, health, and chewing capabilities were correlated with dietary guidelines for the five basic food groups. Chi-square test analysis revealed that subjects with chewing difficulty consumed fewer vegetables. Only 17% of the total subject pool consumed the recommended daily allowance (RDA) of vegetables. Approximately 58% of subjects reported dissatisfaction with their dentures and 51% reported discomfort on chewing. Approximately 4% of the subjects met the RDA standards for all five food groups and 4% did not meet the RDA standards for any of the five food groups. Patient satisfaction with the comfort of their denture during mastication significantly impacted the diet of these elderly edentulous patients.

Purpose: The aim of this study was to evaluate the clinical fracture rate of crowns fabricated with the pressable, leucite-reinforced ceramic IPS Empress, and relate the results to the type of tooth restored. Materials and Methods: The database SCOPUS was searched for clinical studies involving full-coverage crowns made of IPS Empress. To assess the fracture rate of the crowns in relation to the type of restored tooth and study, Poisson regression analysis was used. Results: Seven clinical studies were identified involving 1,487 adhesively luted crowns (mean observation time: 4.5 ± 1.7 years) and 81 crowns cemented with zinc-phosphate cement (mean observation time: 1.6 ± 0.8 years). Fifty-seven of the adhesively luted crowns fractured (3.8%). The majority of fractures (62%) occurred between the third and sixth year after placement. There was no significant influence regarding the test center on fracture rate, but the restored tooth type played a significant role. The hazard rate (per year) for crowns was estimated to be 5 in every 1,000 crowns for incisors, 7 in every 1,000 crowns for premolars, 12 in every 1,000 crowns for canines, and 16 in every 1,000 crowns for molars. One molar crown in the zinc-phosphate group fractured after 1.2 years. Conclusion: Adhesively luted IPS Empress crowns showed a low fracture rate for incisors and premolars and a somewhat higher rate for molars and canines. The sample size of the conventionally luted crowns was too small and the observation period too short to draw meaningful conclusions.

Purpose: Previous studies have shown the relationship of individual clinical variables to the survival of Dicor (Corning Glass Works) restorations. The purpose of the present investigation was to examine the effect of combinations of these variables on the intraoral survival of Dicor restorations. Materials and Methods: Dicor glass-ceramic restorations (n = 1,444) were placed in 417 adult patients. Failure was defined as a restoration that required remake because of material fracture. The survival of restorations with different combinations of variables that were each individually associated with survival was described using Kaplan-Meier survivor functions. The statistical significance of differences in survival between different combinations of specific predictor variables was examined using the proportional hazards model. Results: Kaplan-Meier survival analysis indicated that significantly worse survival rates were found for restorations that included combinations of molar teeth, a dentin core, and a glass-ionomer luting agent; molar teeth, a dentin core, and a resin luting agent; and single-rooted teeth, a dentin core, and a glass-ionomer luting agent than for any other combinations tested. The Cox proportional hazards model described a hazard ratio of 3.37 (95% confidence interval [CI]: 2.23 to 5.08) for molar teeth (versus single-rooted teeth), 2.65 (95% CI: 1.44 to 4.87) for dentin core (versus gold core), 2.35 (95% CI: 1.58 to 3.51) for men (versus women), and 1.72 (95% CI: 1.13 to 2.60) for glass-ionomer luting agent (versus resin) after adjusting for the other variables in the model. Conclusion: Factors beyond individual restoration design impact the survival of Dicor glass-ceramic. These include sex, tooth position, and restorations luted to gold core foundation bases.

Purpose: In this prospective clinical study, the performance of three- and four-unit fixed partial dentures (FPDs) with frameworks fabricated of yttria partially stabilized zirconia was determined after a mean observation period of 50 months. The study focused on the survival of the restoration (in situ criterion) and the success of the ceramic veneers (no defect). Materials and Methods: Seventy-five patients with a maximum of two missing teeth and an antagonistic dentition were treated at the Department of Prosthodontics, University of Goettigen, with 99 posterior FPDs. Fiftyone specimens (experimental group) were veneered with an experimental ceramic suitable for titanium and zirconia frameworks (thermal expansion coefficient [TEC]: 8.5 µm/m*K); 48 restorations (Ceram-S group) were veneered with a commercially available low-fusing ceramic optimized for zirconia frameworks (TEC: 9.5 µm/m*K). All restorations were luted with zinc-phosphate cement. Statistical analysis was performed according to the Kaplan-Meier method; time-dependent success rates of the different types of ceramic veneers were analyzed using the log-rank test. Results: Seven restorations were lost: 4 due to technical complications and 3 due to biologic complications. The overall survival rate after 48 months was 94% (Kaplan-Meier analysis). Twenty-three events required clinical intervention for restoration maintenance: 13 ceramic veneer chippings (polishing), 6 losses of retention (recementation), 3 caries lesions (filling therapy), and 1 loss of vitality (endodontic treatment). Between the two groups of veneering materials, no significant difference in the probability for success was determined (log-rank test, P = .81). Conclusions: Within a mean observation period of 4 years, sufficient survival rates for zirconia-based posterior FPDs could be verified. The main complications included fracture of the ceramic veneering material and decementation, which occurred mainly in the mandible.

This study was designed to evaluate color differences (ΔE) between intended and fabricated shades of various metal-ceramic complexes using visual and instrumental shade determination. Forty-two master disks were made to represent every tab in two shade guides. The shades of the master disks were determined visually and instrumentally. Accordingly, 84 experimental disks were fabricated. Color measurements of the master and fabricated disks were performed using a spectrophotometer. Visual shade determination showed a significantly lower ΔE value than the instrumental shade determination. However, all groups showed ΔE values exceeding 2.75, which could be considered perceivable and therefore clinically unacceptable. A reliable shade duplication of an existing metal-ceramic restoration cannot be ensured, regardless of the method of shade assessment.

There is a constant need for rebasing implant-retained overdentures because of the inevitable continuous absorption of the underlying residual ridge, which results in a lack of proper occlusion and possible rotation of the denture around the retentive components. This step-by-step article describes all of the clinical and laboratory procedures needed for rebasing a mandibular implant overdenture retained with a bar on two implants, securing an accurate fit. This procedure can be applied successfully for rebasing overdentures with different superstructures (ball attachments or magnets), and for replacing worn or damaged retentive components and matrices.

A disposable gnathometer was used to compare measurements of incisal and premolar occlusal forces in removable prosthesis-wearing patients with and without the use of a denture adhesive. Twenty-four patients with maxillary complete dentures opposed by complete or partial mandibular dentures were tested. Denture adhesive significantly improved incisal and premolar occlusal force for the maxillary complete dentures, as well as incisal occlusal force for both existing and new dentures. The occlusal force in patients with mandibular removable partial dentures exceeded that with mandibular complete dentures. Denture adhesive appears to be beneficial for both existing and new dentures, with existing dentures exhibiting an increased benefit relative to newer dentures.

Denture stomatitis is a primarily oral disease that affects denture wearers. The presence of Candida albicans in the palatal mucosa, on the internal surface of the maxillary denture, and in the blood of patients with denture stomatitis was evaluated. Although the results did not show C albicans in the bloodstream of patients, a strong relationship between denture stomatitis and Candida sp was confirmed for both the palatal mucosa and maxillary denture.

Purpose: The aim of this study was to investigate the retentive force of six different attachment systems used for mandibular single-implant overdentures, including two prototype large ball attachment designs. Materials and Methods: Two prototype ball attachments of larger dimensions (7.9 and 5.9 mm) and four commercially available ball and stud attachments of standard dimensions (2.25 and 4.0 mm) were evaluated on three identical test casts resembling an edentulous mandible with severe residual ridge resorption. Five samples from each attachment system (n = 30) were connected to three different implants (8.0-mm wide diameter, 3.75-mm regular diameter, and 4.0-mm regular diameter). An Instron testing machine with a computer software package was used to deliver a vertical dislodging force at a cross-head speed of 50 mm/min to each overdenture sample from the anterior direction. A total of 300 pull tests were conducted (50 per attachment system). The maximum load (retentive force) required to separate each overdenture from the supporting implant was then measured. Results: The highest retentive force (36.97 ± 2.23 N) was achieved with the 7.9-mm prototype ball attachment design, followed in a decreasing order by the 5.9-mm prototype ball attachment design (32.06 ± 2.59 N), the standard 2.25-mm ball attachment (17.32 ± 3.68 N), Locator white (12.39 ± 0.55 N), Locator pink (9.40 N ± 0.74 N), and Locator blue (3.83 ± 0.64 N). A statistically significant difference (P .0001) was found between all attachments. Conclusions: Attachment systems of larger dimensions provided higher retentive forces for mandibular single-implant overdentures. Further in vitro and in vivo research is necessary to determine prosthodontic outcomes with these attachments in edentulous patients prior to their routine clinical use internationally.