The International Journal of Prosthodontics, 03/2014

Purpose: This study compared the surgical protocol efficacy of immediate and delayed implant loading in edentulous maxillae opposed by natural or restored mandibular dentitions over an observational period of 6 years or longer. The selected outcome determinants included individual implant survival data, progressive measurements of peri-implant bone resorption, prosthodontic survival and success data, and report of complications. Materials and Methods: A convenience sample of 49 patients requiring fixed implant-supported maxillary prostheses was split into two groups. The test group (34 patients) was treated according to the Columbus Bridge Protocol, which prescribes the insertion of four to six implants, including distally tilted implants, and load within 24 hours. The control group (15 patients) was treated via a two-stage surgical protocol of 6 to 9 straight implants that were loaded a mean 8.75 months after stage-one implant surgery. Two hundred sixty implants (test: n = 163, control: n = 97) were placed, and all subjects were ultimately treated with screw-retained full-arch prostheses. Results: Two patients dropped out (one in the test group and one in the control group) by the time of the scheduled sixth annual visit. The other patients were followed up for 75.2 months (range: 72 to 90 months). At the 6-year follow-up, no differences in implant cumulative survival rates were found between groups. Significantly less bone loss was found in the test group (mean: 1.62 mm) compared with the control group (mean: 2.44 mm). All of the original prostheses were maintained throughout the study's observation period and were functioning satisfactorily at each patient's last recall appointment. Conclusion: Patients who received immediate and delayed implant loading in their edentulous maxillae demonstrated similar survival outcomes. However, less marginal bone loss was recorded around the immediately loaded implants over the study's 6-year follow-up period.

Purpose: To assess the effect of chemical disinfection procedures on the surface roughness of hard denture base materials. Materials and Methods: A systematic literature review was conducted using five electronic databases (Medline, Cochrane Library, OpenGrey, Lilac, and Google Scholar) along with hand searching of the bibliographies of all located articles. Results: The review yielded 193 articles. This number was reduced to 25 by using defined inclusion and exclusion criteria. Only one in vivo study was included; all others were in vitro evaluations. For every disinfecting agent, studies were found that reported surface alteration after chemical disinfection. The current literature suggests that changes in roughness might be more often associated with sodium perborate (three out of three studies with positive correlation) and less often with chlorhexidine digluconate and glutaraldehyde (two out of seven and one out of four studies with positive correlation, respectively). Because only single studies were found for glycine-type amphoteric surfactant solution, enzyme solution, ethanol, berberine hydrochloride, chlorine, reactive oxygen species, peracetic acid, cetylpyridinium chloride, and citric acid, no conclusions can be drawn about these disinfectants. Conclusions: Physical surface alteration is only one aspect when deciding on the use of chemical disinfection procedures. More research is needed to clarify whether these procedures can be recommended to patients.

This prospective study assessed patient satisfaction before and after single-tooth implant therapy in the esthetic zone. Before implant therapy, patients wore an acrylic resin tissue-supported removable partial denture (RPD). A total of 153 patients were included. Self-administered questionnaires regarding function, comfort, and esthetics were used to measure patient satisfaction with the RPD and with the implant at 6 and 18 months post-implant placement. Overall satisfaction was explored with a visual analog scale. It was suggested that patient satisfaction with a single-tooth implant in the esthetic zone is high and it improved when compared with an RPD that patients wore before implant treatment.

Purpose: To evaluate the difference in cytotoxicity of soft denture lining materials depending on their component types. Materials and Methods: Ten commercially available soft denture lining materials (SDLM) consisting of five silicone-based materials and five acrylic-based materials were evaluated. For the MTT test, cured SDLM samples were extracted in a culture medium for 24 hours, and L-929 cells were incubated in the extracted medium for 24 hours. Cell viability was determined using a microplate reader and compared with those of the negative control, which were cultured in a culture medium without test material. Agar overlay test was performed for the cured SDLM samples according to International Organization for Standardization (ISO) 7405. Results: Among silicone-based lining materials, GC Reline Soft, Mollosil plus, and Dentusil showed a cell viability of 107.2% ± 4.5%, 102.3% ± 2.84%, and 93.0% ± 8.0%, respectively, compared with the control. Mucopren and Sofreliner Tough displayed significantly lower cell viability (86.4% ± 10.3% and 81.5% ± 4.3%, respectively) compared with the control (P < .05). Among acrylic-based materials, Kooliner, Visco-gel, Soft liner, Dura Base, and Coe-Soft displayed cell viability of 99.2% ± 14.6%, 93.1% ± 9.5%, 89.1% ± 9.8%, 87.6% ± 7.9%, and 75.9% ± 15.7%, respectively, compared with the control. Dura Base and Coe-Soft displayed significantly lower cell viability compared to the control. However, for all tested materials, cell viability exceeded the requirement limit of 70% specified in ISO 10993-5. In the agar overlay test, all five silicone-based materials and acrylic-based Kooliner were ranked as "noncytotoxic." However, Visco-gel was ranked as "mildly cytotoxic," and Soft liner, Coe-Soft, and Dura Base were ranked as "moderately cytotoxic." Conclusion: When an acrylic-based soft denture lining material is used, the possibility of a cytotoxic effect should be considered.

Purpose: To assess the Medical Subject Headings (MeSH) indexing of articles that employed time-to-event analyses to report outcomes of dental treatment in patients. Materials and Methods: Articles published in 2008 in 50 dental journals with the highest impact factors were hand searched to identify articles reporting dental treatment outcomes over time in human subjects with time-to-event statistics (included, n = 95), without time-to-event statistics (active controls, n = 91), and all other articles (passive controls, n = 6,769). The search was systematic (kappa 0.92 for screening, 0.86 for eligibility). Outcome-, statistic- and time-related MeSH were identified, and differences in allocation between groups were analyzed with chi-square and Fischer exact statistics. Results: The most frequently allocated MeSH for included and active control articles were "dental restoration failure" (77% and 52%, respectively) and "treatment outcome" (54% and 48%, respectively). Outcome MeSH was similar between these groups (86% and 77%, respectively) and significantly greater than passive controls (10%, P < .001). Significantly more statistical MeSH were allocated to the included articles than to the active or passive controls (67%, 15%, and 1%, respectively, P < .001). Sixty-nine included articles specifically used Kaplan-Meier or life table analyses, but only 42% (n = 29) were indexed as such. Significantly more time-related MeSH were allocated to the included than the active controls (92% and 79%, respectively, P = .02), or to the passive controls (22%, P < .001). Conclusions: MeSH allocation within MEDLINE to time-to-event dental articles was inaccurate and inconsistent. Statistical MeSH were omitted from 30% of the included articles and incorrectly allocated to 15% of active controls. Such errors adversely impact search accuracy.

Purpose: To evaluate the influence of the patient's clinical information on the accuracy as well as interexaminer and intraexaminer reproducibilities of temporomandibular joint (TMJ) magnetic resonance imaging (MRI) scans. Materials and Methods: Forty MRI scans from 20 TMJs corresponding to 7 TMJ pathologies (ie, degenerative alterations of the condyle, degenerative alterations of the mandibular fossa, alterations in the morphology of the TMJ disc, disc displacement with reduction, disc displacement without reduction, TMJ effusion, and TMJ hypermobility) were assessed by seven uncalibrated specialists in temporomandibular disorders (TMD) at baseline, 30 day-, and 60-day follow-ups for accuracy and reproducibility. No clinical information was provided before the 60-day follow up. Results: Examiners had a poor to regular accuracy (0.10 to 0.36), kappa index and 5% to 60% correct positive diagnosis) when compared with the radiologist's diagnoses (gold standard). The interexaminer reproducibility ranged from moderate to substantial (kappa = 0.32 to 0.71), and the intraexaminer reproducibility ranged from moderate to perfect (kappa = 0.38 to 1.00). Provision of clinical information improved neither the accuracy nor the reproducibility of the results (P < .05), with the exception of the intraexaminer reproducibility of one examiner. Conclusions: Calibration is needed in assessing TMJ MRI scans, even when trained specialists are provided with clinical information from the patient.

An association between oral health, number of teeth, and mortality has been reported in the literature, but limited knowledge is available on mortality in elderly partially edentulous and edentulous patients treated with implants. Purpose: The aim of this retrospective study was to compare the mortality pattern in elderly patients (80 years or older) who were provided with implants and were partially or completely edentulous. Materials and Methods: Between 1986 and 2003, a total of 266 elderly patients with a mean age of 83.0 years at the time of implant placement were included. The patients were provided with 1,384 Brånemark System implants (Nobel Biocare) in 285 arches. The sample was divided into two subgroups: 108 edentulous patients and 158 partially edentulous patients. Information was collected for each individual regarding expected remaining lifetime at the time of implant surgery. Cumulative survival rate (CSR) was calculated and compared for the two subgroups covering 10 years and was also compared to expected CSR data for normal populations of comparable distribution. Results: Mortality was significantly decreased (P < .05) for partially edentulous compared with edentulous patients (-10.4%) after 10 years of follow-up. CSR for the elderly groups showed a significant decrease in mortality compared with comparable groups of normal populations (P < .05). There was no significant difference in morality between healthy/nonhealthy patients at first surgery or patients with reported/unreported implant failures (P > .05). Conclusions: Elderly partially edentulous patients had significantly lower mortality compared with edentulous patients over a 10-year period of followup. Both subgroups also showed significantly lower mortality compared with normal populations of comparable sex and age at the time of implant surgery. The observation is interpreted as that these patients are healthier and more motivated to replace their lost teeth with implants than the normal population rather than that implant treatment per se reduces mortality.

Purpose: To evaluate the long-term cost-effectiveness of five treatment alternatives for maxillary lateral incisor agenesis where space maintenance and tooth replacement are indicated. Materials and Methods: The following treatment modalities were considered: single-tooth implant-supported crown, resin-bonded fixed partial denture (FPD), cantilever FPD, full-coverage FPD, and autotransplantation. The cost-effectiveness for each treatment modality was determined as the ratio of the outcome of each modality divided by the cost. Direct costs, clinical and laboratory, were calculated based on national fee schedules and converted to international dollars using purchasing power parity exchange rates. Outcomes were based on the most recently published long-term (10-year) survival rates. Sensitivity analyses were carried out, testing the robustness of the cost-effectiveness analysis. Results: The five treatment modalities ranked in the following order from most to least cost-effective: autotransplantation, cantilever FPDs, resin-bonded FPDs, single-tooth implants and implant-supported crowns, and full-coverage FPDs. Sensitivity analysis illustrated that the cost-effectiveness analysis was reliable in identifying autotransplantation as the most and full-coverage FPDs as the least cost-effective treatment modalities. Conclusions: When replacing a missing maxillary lateral incisor, the most costeffective, long-term treatment modality is autotransplantation, whereas the least cost-effective is full-coverage FPDs. However, factors such as patient age, the state of the dentition, occlusion, and tooth conservation should also influence the choice of restoration.

This study aimed to evaluate the fracture resistance of monolithic single crowns made from zirconia (ZI), lithium disilicate (LS2), or feldspar ceramic (FC). Five groups of crowns representing a maxillary first molar were made with the appropriate dimensions according to the manufacturer's instructions. The ZI and LS2 crowns were luted adhesively or cemented conventionally on a metal abutment tooth analog. The feldspar ceramic crowns were luted adhesively. All specimens underwent axial loading until fracture. The crowns in the ZI groups possessed the highest fracture resistance independent of the mode of fixation.

Purpose: To compare the shear bond strength (SBS) values of resin cement to zirconia treated with a new activating method. Materials and Methods: Forty-five zirconia specimens were divided into three groups: no treatment (group 1), plasma of argon cleaning for 375 seconds (group 2), and plasma of argon cleaning for 750 seconds (group 3). Composite cylinders were bonded with a self-adhesive cement. After 40 days of water storage, specimens were subjected to the SBS test. Data were analyzed with one-way analysis of variance and the Neuman-Keuls multiple comparison test. Results: Test groups obtained SBS values significantly higher (101% for group 2 and 81% for group 3) than controls. Conclusion: Plasma of argon appeared to improve bonding between zirconia and resin cement.

Purpose: This prospective, cross-sectional study evaluated the relationship between bone mineral density (BMD) and the width and height parameters of the mandibular residual ridge. Materials and Methods: BMD was determined in the lumbar spine and femoral necks by dual energy x-ray absorptiometry (DXA) in 45 edentulous, postmenopausal women (mean age, 72.08 ± 8.53 years) who had used conventional complete dentures for at least 3 years. Measurements of the mandibular residual ridge were performed using cone beam computed tomography (CBCT). Height and width measurements were performed in the midline and adjacent to the mental foramina. Data were analyzed with descriptive and analytic statistics. The relationship between BMD and mandibular height and width measurements was assessed using analysis of variance as well as linear and multivariate regression analyses. Eight patients were excluded from the study because they did not complete both of the required imaging analyses (DXA and/or CBCT). Results: There was no statistically significant relationship between BMD and mandibular bone height measurements in the midline and both regions of the mental foramina, and no statistically significant relationship existed between BMD and mandibular bone width measurements in the midline and both of the mental foramina regions. Conclusions: Postmenopausal women with reduced general BMD do not appear to have a reduction in the size of the mandibular residual ridge.

During dental treatment, patients can swallow or inhale a foreign object as a result of several patient- and clinician-related factors; however, several methods can be used to prevent this complication. A 65-year-old man was referred to the Oral Implantology Clinic at the University of Amsterdam (ACTA) for a fixed prosthesis in the maxilla. While placing the implants, the screwdriver accidentally slipped from the fingers of the surgeon and was ingested by the patient. Since the difference between swallowing and inhaling cannot be accurately diagnosed, patient followup is advisable.

Osseointegrated implants have been well documented for retaining an obturator prosthesis as well as a facial prosthesis. However, when the defect extends to both the facial area and the maxilla, it is difficult to rehabilitate those defects to the satisfaction of the patient, especially in cases where implants cannot be placed on both sites. This case report describes the use of magnets to connect two prostheses, thereby increasing retention and patient comfort.