The International Journal of Prosthodontics, 05/2006

Purpose: Sleep bruxism (SB) is associated with temporomandibular pain, headaches, tooth wear, and disruption of the bed partner's sleep. The aim of this report was to compare SB treatments from various experimental studies to guide the selection of a treatment for a large sample size study. Materials and Methods: After a literature search, randomized controlled studies of 7 pharmacologic treatments and 3 oral devices were included. The number needed to treat (NNT) was calculated from raw data from the sleep laboratory at the Hôpital du Sacré-Coeur, Montréal or from published articles when sufficient data were available. The effect size (ES) was calculated for all included studies. In the most effective treatments, the NNT ranged from 1 to 4, while a high ES was above 0.8. Results: The treatments with the best NNT and ES results were the mandibular advancement device (MAD) and clonidine. The NNT (± 95% CI) and ES were 2.2 (1.4 to 5.3) and 1.5 for the MAD, and 3.2 (1.7 to 37.3) and 0.9 for clonidine, respectively. An NNT of 3.8 (1.9 to -69.4) and an ES of 0.6 were observed with the occlusal splint, with a reduction of 42% in the SB index. NNT could not be calculated for clonazepam, although the ES was 0.9. Conclusion: Although the NNT and ES results seem to indicate that the MAD and clonidine are the most promising experimental treatments, both treatments were associated with side effects (ie, discomfort for the MAD; REM suppression and morning hypotension for clonidine). The occlusal splint and clonazepam seem to be acceptable short-term alternatives, although further longitudinal, large sample size randomized controlled trials in SB management are needed.

Purpose: This investigation compared initial and fatigue strengths of particle-abraded ceramics to those of as-polished alumina and zirconia ceramics in crown-like layer structures. Materials and Methods: Alumina or zirconia plates bonded to polycarbonate substrates were subjected to single-cycle and multi-cycle contact (fatigue) loading. Cementation surfaces of the ceramic were damaged by controlled particle abrasion, indentation with a sharp diamond at low load, or a blunt indenter at high load. The stresses needed to initiate radial fractures were evaluated. Results: The strengths of specimens were lowered by fatigue loading. After the equivalent of 1 year of occlusal contacts, the strengths of undamaged specimens degraded to approximately half of their single-cycle values. In particle-abraded specimens, an additional 20% to 30% drop in strength occurred after several hundred load cycles. Particle abrasion damage was approximately equivalent to damage from sharp indentation at low load or blunt indentation at high load. Conclusion: Damage from particle abrasion, not necessarily immediately apparent, compromised the fatigue strength of zirconia and alumina ceramics in crown-like structures. In fatigue, small flaws introduced by particle abrasion can outweigh any countervailing strengthening effect from compression associated with surface damage or, in the case of zirconia, with phase transformation.

Purpose: This study aimed to correlate the general well-being of patients and their judgment about their dental appearance. Materials and Methods: Based on internationally accepted guidelines regarding dental esthetics, a questionnaire was developed to measure subjective assessments of dental appearance. Fourteen items defined an esthetic sum score (0 = satisfied; 56 = dissatisfied). Further, general well-being was evaluated with a long-established and highly reliable test. Eighty participants were included (47 women, 33 men). Participants were drawn from 4 different groups (n = 20): natural dentition (group N), fixed partial dentures (group F), removable partial dentures (group R), and patients who had an esthetic problem with their teeth (group P). Results: Seventy-five participants showed a normal well-being. Five participants showed a depressive state and formed a new group (group D). The medians of the sum scores (25th, 75th percentile) were: group N: 12 (10, 14); group F: 14 (8, 29); group R: 14 (9, 27); group P: 23 (18, 35); group D: 30 (26, 35). Significant differences were found between groups N and P, as well as between group D and groups N, F, and R. Conclusion: Because of the significant difference between groups N and P, basis validation of the sum score was achieved. Further, self-assessments of dental appearance appeared to be more negative for participants with a depressive state compared with the other groups. In clinical studies, selection bias can be prevented by using a test that measures well-being to verify if a study sample includes a normal number of depressive subjects and therefore represents the general population.

Purpose: To measure the long-term changes of clinical crown height in patients treated with single-implant crowns and compare them to those of an adult population with normal dentition. Materials and Methods: The test group comprised 23 patients, consecutively restored with a total of 48 single-implant crowns in the anterior maxilla. Mean age was 26.1 ± 11.4 years at inclusion. Original master casts were stored after treatment, and patients were recalled for new study casts an average of 15.8 ± 0.74 years later. The control group comprised 141 dental students with a mean age of 22.9 ± 1.20 years at inclusion. Study casts were made at inclusion and after 10 (n = 141) and 20 years (n = 60). Clinical crown height was measured for maxillary anterior teeth, and data were pooled and compared regarding clinical crown height and changes in height. Results: Implant clinical crowns were an average of 0.6 ± 1.04 mm longer than the contralateral teeth (P .05). Central and lateral incisors showed mucosal recession at an average of 0.4 ± 0.53 mm (P .05) and 0.6 ± 0.58 mm (P .01), respectively. In the control group, only minor insignificant changes (± 0.1 mm) in mean clinical crown height could be observed during the follow-up period. However, obvious individual variations of changes could be found in the control group, and were more pronounced for women. Altogether, 15% and 9% of measured teeth showed >= 1.0 mm increase or decrease of clinical crown height during 20 years, respectively. Initially, shorter teeth presented a trend (P .05 to .001) of more mucosal recession than longer teeth. Conclusion: Mean values of clinical crown height disguise significant individual variations of changes. To perform a risk evaluation for potential future mucosal recession, it could be suggested that greater changes in clinical crown height may occur in patients provided with implant-supported crowns than in untreated control subjects, possibly more for women than men, and more for initially shorter teeth than for longer adjacent teeth.

Purpose: To determine the optimal thickness of protective oral radiation shields composed of an acrylic resin stent and a lead shield, which are used in head and neck radiotherapy to minimize undesired normal tissue radiomorbidity. Materials and Methods: Intraoral acrylic resin stents and lead shields of different thicknesses were inserted into a specially designed human mandible phantom with thermoluminescent lithium fluoride dosimeter chips (TLD-100) placed on the buccal and lingual sites and exposed to irradiation of different energies. Fifty-cGy irradiation was performed and TLD-100 dose measurements were obtained for each irradiation type, acrylic resin stent thickness, and lead shield thickness. Results: Acrylic resin stents with a 2-mm lead shield reduced 20% and 15% of the normal tissue dose for Co-60 and 6 MV X photon radiations, respectively, whereas the stents with a 4-mm lead shield achieved a higher reduction of the normal tissue dose (30% and 23% for Co-60 and 6 MV X photons, respectively). Conclusion: In protective oral radiation shields, acrylic resin stent thickness has little effect on the reduction of normal tissue dose, but lead shield thickness significantly effects the reduction of normal tissue dose.

Purpose: To investigate the feasibility of obtaining expert consensus on the prosthodontic principles to be followed when constructing complete dentures, so that any modifications to materials and methods would not sacrifice those principles-a philosophy known as "appropriatech." These principles would then comprise a Minimum Acceptable Protocol (MAP) for complete dentures. Materials and Methods: A Delphi survey technique was used that requested yes/no answers to a variety of statements describing the different stages in the construction of complete dentures. Respondents could also provide comments on any aspect of the questionnaire. The statements were then modified in light of the responses and comments received, and recirculated. Three rounds of questionnaires were used, and only statements achieving a 90% or greater consensus were included in the MAP. The respondents were randomly selected by country from the 2004 membership e-mail list of the International College of Prosthodontists. Results: Forty-one respondents answered the first questionnaire, 39 the second, and 36 the third. The 75 statements in the first questionnaire were gradually reduced as consensus was reached, and eventually 18 statements remained with 90% or greater agreement. Conclusion: Even though expert opinion is regarded as the lowest level of evidence, there are no other methods available to derive such a protocol, and the Delphi technique was useful in obtaining the consensus. This MAP could now be used to help assess clinical techniques that attempt to reduce time and costs while producing a quality service-in other words, which will conform to the philosophy of appropriatech.

Purpose: This study aimed to investigate the effect of age, posterior occlusal contacts, occlusal force, and salivary flow on masticatory performance in older adults. Materials and Methods: The study sample consisted of 328 independently living people over the age of 60 years. Masticatory performance was determined by the concentration of dissolved glucose obtained from test gummy jellies, which are the standardized food developed for measuring masticatory performance. Bilateral maximal occlusal force in the intercuspal position was measured with pressure-sensitive sheets. Stimulated whole saliva was collected using the mastication method. Subjects were grouped into 3 categories by posterior occlusal contacts according to the Eichner Index. Results: The multiple linear regression analysis showed that, with other variables controlled, masticatory performance was significantly associated with posterior occlusal contacts (b = -.24, P .001 for Eichner group B; b = -.52, P .001 for Eichner group C), occlusal force (b = .28, P .001), and hyposalivation (b = -.08, P .046) (R2 = 0.49). Within the groups classified by the Eichner Index, occlusal force was significantly associated with masticatory performance; however, age was not. For salivary flow rate, hyposalivation had a significant relationship with masticatory performance in group C (P = .003) and group B (P = .047), but no significant relationship in group A. Conclusion: A decline of posterior occlusal contacts, occlusal force, and hyposalivation appear to be associated with masticatory performance with aging in older adults.

Purpose: The aim of this pilot study was to evaluate and determine psychogenic aspects of prosthesis incompatibility by psychologic tests that define the (psychogenic) prosthesis incompatibility as a psychologic disorder. The patients' complaints with the restorations included taste disorders, odynophagia, pain sensations, and functional and esthetic dissatisfaction. Materials and Methods: The study cohort comprised 83 patients with complete dentures fabricated according to a standardized protocol. A dental history questionnaire was used to evaluate whether the patients had adapted to their dentures 6 months after incorporation. Twelve patients with suspected psychogenic prosthesis incompatibility and a group of 24 randomly selected control subjects were evaluated by application of the psychologic tests Symptom Checklist-90-R (SCL-90-R) and the Center of Epidemiological Studies Depression Scale (CES-D). Results: When compared with the control group, patients with suspected psychogenic dental prosthesis incompatibility showed statistically significant differences in the CES-D cumulative values (P = .015) and the SCL-90-R values Global Severity Index (P = .024) and Positive Symptom Distress Index (P = .049). Conclusion: This was the first documented study to use the SCL-90-R and CES-D scales on patients with suspected psychogenic dental prosthesis incompatibility with nonadaptation 6 months after incorporation. Adaptation problems were ruled out as a possible cause. Using the SCL-90-R and CES-D, it was possible to make a reliable initial diagnosis of the psychosomatic clinical situation regarding psychogenic prosthesis incompatibility. The results have direct implications on socioeconomic and forensic consequences for diagnosis and treatment by a dental clinician.

Purpose: Recent studies implicate smoking as a significant factor in the failure of dental implants. The purpose of this long-term retrospective study was to evaluate the survival of Brånemark endosseous dental implants in relation to cigarette smoking. Materials and Methods: The sample consisted of 464 consecutively treated completely and partially edentulous patients who had a total of 1852 implants placed between 1979 and 1999, and who were part of a surgical/prosthodontic prospective treatment outcomes study. The effect of cigarette smoking on implant survival in relation to the time of implant failure, gender, age, surgeon, date and site of implant placement, implant length and diameter, prosthesis design, and occlusal loading considerations was assessed in bivariate and multivariate survival analyses. Results: The overall implant failure rate was 7.72%. Patients who were smokers at the time of implant surgery had a significantly higher implant failure rate (23.08%) than nonsmokers (13.33%). Multivariate survival analysis showed early implant failure to be significantly associated with smoking at the time of stage 1 surgery and late implant failure to be significantly associated with a positive smoking history. Short implants and implant placement in the maxilla were additional independent risk factors for implant failure. Conclusion: Cigarette smoking should not be an absolute contraindication for implant therapy; however, patients should be informed that they are at a slightly greater risk of implant failure if they smoke during the initial healing phase following implant insertion or if they have a significant smoking history.

Purpose: The aim of this pilot study was to investigate a universal and easy method for improving the speech function of complete maxillary dentures. Specifically, it was analyzed whether sandblasting could improve speech performance, since this process increases the tactile surface area in the region of tongue-to-denture contact. Materials and Methods: Fourteen volunteers with complete maxillary dentures in a geriatric rehabilitation center (7 men, 7 women, mean age 81.2) were recruited. Speech samples (normal conversation, logopedic standard text, and a word list) were recorded for all subjects. In 11 cases, a specific area of the denture was sandblasted, while the remaining 3 cases served as controls. After 1 week of service, the same speech samples were recorded again. The rating of the speech samples was performed by 2 experienced speech therapists. The rater did not know whether the sample was a control case or whether it was before or after intervention. Results: The speech therapists found no difference between the 2 speech samples in all 3 cases in the control group. For 8 of 11 subjects, the speech sample after sandblasting was rated better by both therapists (P = .002). In 2 subjects, no difference was observed, and deterioration was found in only 1 subject by 1 speech therapist. Conclusion: Taking into account the limited number of subjects, the results show that sandblasting may lead to moderate improvements in speech performance in most cases. Deterioration is not expected, but in such cases, it is easy to restore the denture with simple polishing.

This study evaluated the influence of the cementation length of glass fiber-reinforced composite (FRC) on the fatigue resistance of bovine teeth restored with an adhesively cemented FRC. Thirty roots of single-rooted bovine teeth were allocated to 3 groups (n = 10), according to the ratio of crown length/root length (post cementation length): group 1 = 2/3, group 2 = 1/2, and group 3 = 1/1. The roots were prepared, the fiber posts (FRC Postec Plus) were cemented, and the specimens were submitted to 2 million mechanical cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture, and data were submitted to statistical analysis. All specimens were resistant to fatigue. Taking into account the methodology and results of this study, the evaluated fiber posts can be cemented based on the ratio of crown/root at 1/1. Further clinical studies must be conducted to verify this ratio.

Purpose: This in vitro study aimed to investigate the influence of (1) the interimplant distance and (2) the type of attachment on the retention of mandibular overdentures on 2 implants. Materials and Methods: Three stone casts were fabricated, each with 2 implant analogues embedded at distances of 19, 23, and 29 mm apart. Three different interchangeable mandibular overdenture attachments were secured onto the analogues: Hader bars, ball abutments, and stainless steel keepers for new generation neodymium-iron-boron magnets. In total, 45 groups of paired attachments were tested for initial vertical peak tensile load at the 3 interimplant distances. Results: Interimplant (interclip) distance played a significant role only in the retention produced by the Hader bar/red clip configuration. At 19 and 23 mm, the ball/socket attachments were statistically more retentive than the yellow clips, white clips, and magnets, but not compared to the red clips. At 29 mm, the ball abutments showed statistical superiority compared with all other attachments. Mean clinical intercanine distance for conventional full dentures was 22.88 mm. Conclusion: Interimplant distance can affect the initial retention of mandibular overdentures on 2 implants depending on the type of attachment used. For a predetermined interimplant distance, attachment performance varies greatly.

Research has shown a decrease in femoral bone-to-implant contact in rats with uncontrolled diabetes. The present study aimed to test the hypothesis that this decrease may be the result of a decreased mineral apposition rate. In 20 normal and 20 diabetic rats, a titanium implant was inserted into the tooth extraction socket immediately after the right maxillary molars were extracted. There was a significantly reduced mineral apposition rate in the diabetic rats compared with the normal rats (P = .0001), but no difference between rats sacrificed at 20 and 40 days (P = .297). The results suggest that implant insertion immediately following tooth extraction in patients with poorly controlled diabetes is contraindicated.

Purpose: This clinical trial aimed to evaluate the outcomes of implant-supported mandibular overdentures (ISMOs) using 2 different loading protocols. Materials and Methods: Two groups of 10 edentulous patients each were selected for the study. Each patient received 2 implants placed in the mandibular canine sites. After 1 week, ISMOs were delivered to the 10 patients in the test group, while conventional mandibular dentures were delivered to the 10 patients in the control group. The conventional prostheses were converted to ISMOs after 3 months. Treatment outcomes for the ISMOs were evaluated 1 year after implant surgery. Results: The number of appointments and time needed for fabrication of ISMOs revealed statistically significant differences between the patient groups. The requirements for prosthodontic maintenance of ISMOs in the test group were higher than those in the control group; however, these differences were not statistically significant. The mean marginal bone resorption for each group was 0.3 mm after 1 year. Conclusion: The results of this clinical trial suggest that early loading of a specific length of implants used to support mandibular overdentures does not jeopardize treatment outcomes during the first year of service.