The International Journal of Prosthodontics, 03/2008

Purpose: The purpose of this study was to evaluate patient-specific outcomes and satisfaction using dental implants in a population affected with ectodermal dysplasia. Materials and Methods: Patient-based data were collected using a self-reported survey instrument sent to patients belonging to a private patient foundation and/or treated previously at a government clinic. A standardized survey instrument was developed to evaluate patient satisfaction, outcomes, and potential complications using dental implants. Results: The survey instrument was mailed to 253 affected individuals self-reported to have various forms of ectodermal dysplasia and who were voluntarily participants in the National Foundation for Ectodermal Dysplasias and/or were participants in the US National Institute for Dental Craniofacial Research Intramural Ectodermal Dysplasia clinical research program. A total of 109 responses were obtained (43% response rate). The duration following completion of implant therapy ranged from to 1 to 23 years. Of the 109 participants, 50% reported either an implant or prosthetic complication with implant treatment, and 24% reported some form of failure with implant therapy. However, 91% of participants reported being either satisfied or very satisfied with dental implants, and 95% reported that the treatment was worth the time and cost. Conclusions: Affected individuals receiving tooth replacement therapy with dental implants reported satisfaction with the outcome. A higher level of complications, including infection, mechanical problems, and implant loss, relative to the unaffected population was reported.

Purpose: This study aimed to assess the use of neuropsychologic tests as a tool to differentiate, or not, between a nonresponding chronic pain condition of nonmuscular origin, irritable bowel syndrome (IBS) (n = 20), versus 2 pain conditions of muscular origin, responding (n = 36) and nonresponding (n = 24) temporomandibular disorders. Materials and Methods: The neuropsychologic tests used were the simple and multiple-choice reaction-time tests, California Verbal Learning Tests, the Brown-Peterson Consonant Trigram Auditory Memory Test, Sleep Assessment Questionnaire, and Beck Depression Inventory, as well as fatigue and energy level assessments (100-mm visual analog scale). Results: Most of the tests used were capable of significantly differentiating between responding TMD versus IBS patients. Conversely, no statistically significant difference was found between nonresponding TMD versus IBS patients. Overall, the nonresponding TMD and IBS groups did worse in the neuropsychologic assessment than the responding TMD group, with higher memory deficits, levels of depression and fatigue, more sleep disturbances, and lower energy levels. Conclusions: These data suggested that 2 nonresponding chronic pain conditions of different origins may share similar neuropsychologic test results compared to a responding condition. These findings are consistent with the hypothesis that nonresponding chronic pain disorders, irrespective of peripheral location, may be regulated centrally and have similar neuropsychologic impacts.

Purpose: When planning and budgeting for a clinical trial, researchers have few references to help them estimate how many volunteers will need to be screened, how long the screening process may take, and how much it may cost to enroll sufficient qualified subjects. The purpose of this study was to analyze the time and costs involved in recruiting, screening, and enrolling subjects for a randomized clinical trial examining patient satisfaction with mandibular dentures retained by 1 or 2 implants. Materials and Methods: Data collected included age and sex of volunteers, recruiting sources, length of time and costs of recruiting and screening volunteers, and reasons for inclusion or exclusion. Results were analyzed using Pearson chi-square tests. Results: We estimated that we would need to screen 180 volunteers over a period of 4 years at an estimated total cost of CAN$47,664.00 to enroll 86 subjects. Instead, we had to screen 220 volunteers at a direct cost of $63,324.81. We excluded 28% of volunteers, while 32% declined participation and 40% agreed to participate in the study. Volunteers were most commonly excluded because of technical problems with their existing dentures, while they were most likely to decline participation because of perceived surgical risks with implants. Those who agreed to participate most commonly cited anticipation of a more secure mandibular denture as their reason for enrolling. Conclusion: We had to screen more volunteers at a higher cost than anticipated, with only 40% of those screened meeting inclusion criteria and agreeing to participate in the trial.

This study aimed to analyze the influence of different retraction techniques (pure cotton cord, cord impregnated with epinephrine, and chemical retraction [Expa-syl]) on the crevicular fluid flow in vivo. A total of 340 prepared teeth were randomly assigned to one of the retraction procedures. Crevicular fluid flow was measured prior to and immediately after the removal of the respective retraction material. Pure cotton cords led to a significant increase in crevicular fluid flow, whereas impregnated cords and Expa-syl significantly reduced crevicular fluid flow (P .01). The retraction technique has a high impact on the reduction of crevicular fluid flow in patients. Pure cotton retraction cords should be avoided.

Purpose: The aim of this prospective study was to evaluate the clinical performance of anterior and posterior fixed partial dentures (FPDs) with frameworks made using DC-Zirkon after a mean observation time of 3 years. Materials and Methods: Forty-six patients with 1 to 3 missing anterior or posterior teeth were included in this study. All abutment teeth were prepared for full crowns with a chamfer preparation of 0.6 to 0.8 mm. The zirconia frameworks were produced with the Precident DCS system and veneered with veneering porcelain (Vita D). A self-curing resin cement was used for the anterior FPDs and a conventional zinc oxide phosphate cement was used for the posterior FPDs. Results: Fifteen anterior FPDs and 50 posterior FPDs were recalled at least once a year after cementation. The mean observation period was 38 (± 18.0) months for the anterior FPDs and 37 (± 15.5) months for the posterior FPDs. Within the observation time, no remakes were necessary, but in 4 cases a small chipping of the veneering material occurred in the posterior region. Two FPDs were recemented after decementation, and 3 teeth needed endodontic treatment. No negative influences at the gingival margin were observed. Conclusions: Within the mean observation time of 3 years, zirconia-based FPDs demonstrated a sufficient success rate under clinical conditions. However, special attention should be paid to designing the zirconia framework to ensure a sufficient veneering layer thickness with a range between 1 to 2 mm.

Purpose: The aim of this prospective study was to evaluate the clinical performance of fully sintered hot isostatic pressed yttria-partially-stabilized zirconia (Denzir) 3-unit fixed partial dentures (FPDs). Materials and Methods: Nineteen 3-unit FPDs were placed in 18 patients. Ten FPDs were placed in the maxilla and 9 in the mandible. Two calibrated examiners evaluated the FPDs independently 1 week (baseline), 1 year, 3 years, and 5 years after placement using the California Dental Association quality evaluation system. Results: All FPDs were intact at the 5-year examination. One FPD lost retention after 12 months but remained intact; it was recemented and is still in function after 5 years. All FPDs were rated satisfactory over 5 years. No changes were seen in terms of color and anatomic form. The number of slightly rough or pitted occlusal surfaces increased approximately 30% over 5 years. Visible evidence of ditching along the margin increased over time, but only for those FPDs luted with zinc phosphate cement. Conclusion: The 5-year results indicate that yttria-partially-stabilized zirconia 3-unit FPDs with anatomically designed frameworks are promising prosthetic alternatives, even in the premolar and molar regions. However, for all-ceramic FPDs with more units in function, further studies are necessary.

Purpose: This study compared the fracture strength of direct anterior cantilever fiber-reinforced composite (FRC) fixed partial dentures (FPD) reinforced with 3 types of E-glass fibers preimpregnated with either urethane tetramethacrylate, bisphenol glycidylmethacrylate/polymethyl methacrylate, or bisphenol glycidylmethacrylate monomers and 1 ultrahigh molecular weight polyethylene fiber. Failure types were also evaluated. Materials and Methods: A total of 40 caries-free, human maxillary central incisors (n = 10 per group) received surface-retained direct cantilever restoration (1 pontic) after etching and application of bonding agent. Four FRC materials were used (FRC1 = EverStick; FRC2 = BR-100; FRC3 = Interling; FRC4 = Ribbond), and pontics were built up using 1 particulate filler composite (Clearfil Photo Posterior). After the fracture test, failure types were analyzed. Results: No significant difference was found between the 4 FRC types veneered with particulate filler composite (893 ± 459 N to 1326 ± 391 N) (P = .1278). Complete pontic fracture at the connector area was most prominent for FRC4 (90%), followed by FRC3 (70%). Only FRC2 (10%) showed some fiber fractures, with half of the fiber remaining attached on the enamel surface of the abutment. Conclusion: The fracture strengths of cantilever FPDs made of 4 FRC materials with different monomer matrices and architectures, veneered with particulate filler composite, did not show significant differences. However, failure behavior varied between groups.

Retention systems for implant-retained auricular prostheses using either bar-clip attachments with 2 or 3 clips or retention with 2 or 3 magnets were wear tested (insertion and removal cycles) to simulate clinical periods of use. Measurements were taken at intervals of 540 cycles, which represents a period of use of approximately 6 months, for up to 3,240 cycles. Assessments of retentive force were carried out before, during, and after the wear test. Statistical analysis indicated that the bar-clip systems provided higher retention than the magnetic systems. The bar-clip attachment with 2 clips showed a significant loss of retentive force after wear testing (P .05), suggesting lower durability and shorter clinical life. The retention provided by the bar-clip attachment with 3 clips remained stronger than that provided by all other systems tested. At the end of the wear test, the magnetic systems showed very little loss of retention but were still less retentive than the bar-clip systems, suggesting higher durability under clinical simulation despite the lower retention initially provided.

This study evaluated the fracture strength and microtensile bond strength of a new computer-aided design (CAD) veneering method for zirconia frameworks. A new CAD/computer-assisted manufacture system was used to fabricate a resin replica of the esthetic ceramic required to veneer a zirconia framework. The replicas were processed using press-on technology. Identical manually layered zirconia specimens served as a control (n = 18; a = .05). Statistical analysis revealed that the fracture strength (442.8 ± 25 N) and microtensile bond strength (26.6 ± 2 MPa) of CAD-veneered zirconia were significantly higher (P .001) compared to the control (346 ± 24 N and 15.1 ± 1 MPa, respectively). CAD veneering is a reliable method for veneering zirconia frameworks.

The aims of this study were to evaluate the success rates and peri-implant soft tissue responses of auricular implants, to assess prosthetic complications, and to calculate the survival rate of silicone auricular prostheses. Twenty-nine extraoral implants were placed in 10 patients with 11 auricular defects. Implant failure was defined as clinically detectable implant mobility, and a 5-point scale was used to record the health of peri-implant soft tissues. Prosthetic complications were assessed, and the survival rate of silicone auricular prostheses was calculated using Kaplan-Meier analysis. The implant success rate was 100%. A few soft tissue problems were noted. The overall cumulative survival rate for the first prostheses of the patients was 70% after 18 months. The mean survival time was 17 months. Extraoral implants had a very high success rate in the mastoid region. Prosthetic assessment indicated that although experience with wearing prostheses reduces retention degradation, discoloration and reduced quality of fit at the prosthesis edge over time remain the major problems in maxillofacial prosthetics.

Purpose: The aim of this study was to quantitatively measure tooth and ceramic wear over a 2-year period using a novel superimposition technique. Three ceramic systems-experimental hot-pressed ceramic (EC), Procera AllCeram (PA), and metal-ceramic-were used. Materials and Methods: A total of 90 posterior crowns in 48 patients were randomized into 3 groups, and impressions were made at baseline and at 6-month intervals for 2 years. Clinical images were taken after using a dye to highlight surface changes. The impressions were digitized and modeled as superimposable 3-dimensional colored surface images. The depth of wear at the occlusal contact areas was quantitatively measured at 6, 12, 18, and 24 months. Results: The quantitative evaluation showed more wear in Procera AllCeram at the occlusal contact areas, whereas the experimental and metal-ceramic systems showed less wear. There was a significant difference in the amount of enamel worn between all types of restorations (P .05). There was a statistically significant difference (P .05) in the mean depth of wear between all systems. Conclusions: The metal-ceramic and experimental systems showed less change, indicating improved wear resistance compared with Procera AllCeram. In addition, enamel opposing metal-ceramic and experimental crowns showed less wear compared to enamel opposed by Procera AllCeram crowns.

Purpose: The bite stop (jig) is commonly used in clinical practice. It has been recommended as a simple means to routinely record or provide centric relation closure and, more recently, to reduce migraines and tension-type headaches. However, the reason for the jig effect has yet to be explained. This study tested the hypothesis that it works through a decrease in masticatory muscle activity. Materials and Methods: The effect of a jig placed on the maxillary anterior teeth was investigated by recording the electromyographic (EMG) activity of the superficial masseter and anterior temporal muscles at postural position and when swallowing on the jig. EMG recordings were obtained from 2 groups of pain patients (myofascial and neuropathic) and from 2 groups of pain-free patients (disc derangement and controls) unaware of the role of dental occlusion treatments. Results: EMG activity in postural position was higher in pain groups than in pain-free groups. The jig strongly but temporarily decreased the postural EMG activity for masseter muscles in all groups except for the neuropathic group and for temporal muscles in the myofascial group. The EMG activity when swallowing with the jig was reduced in control, disc derangement, and myofascial groups; however, EMG "hyperactivity" in the neuropathic pain group seemed to be locked. Conclusions: The decrease of postural EMG activity, especially in the myofascial group, was short lasting and cannot be considered as evidence to support the hypothesis of a long-term muscle relaxation jig effect. However, the results may uphold certain short-term clinical approaches.

Purpose: This study evaluated treatment outcomes of 4-unit porcelain-fused-to-gold fixed dental prostheses (FDPs) replacing 2 adjacent missing teeth. Materials and Methods: A total of 102 FDPs made in an undergraduate university clinic for 73 patients were evaluated for up to 20 years, with a mean survival follow-up time of 11.4 years. All patients were offered an oral health maintenance program. Treatment failures were divided into irreversible (loss of FDPs/finish line involved) or reversible (FDPs and finish line intact after conservative treatment) complications and into biologic and technical/patient-related failures. Results: The Kaplan-Meier overall estimated survival rate was 68.3% at year 20. There was a statistically significant difference (P = .007) between the survival rates in the maxilla for the vital group (73.8%) and those for the root canal-treated group (25.1%). Comparing the survival rate in the root canal-treated group for the restorations in the maxilla (25.1%) versus the mandible (66.8%), a statistically significant difference (P = .011) was found. The main reason for irreversible failure was caries (32.0%). Conclusion: The estimated successful outcome of 4-unit FDPs over an up to 20-year period is considered favorable and should be compared with the survival rates of other treatment options for the replacement of 2 adjacent teeth. Occurrence of a previously reversible complication appears to be a predictive factor for an irreversible complication later on. A reversible complication within the first 2 years will lead to an early irreversible complication.