The International Journal of Prosthodontics, 01/2007

Purpose: This article presents a rationale for retrievability of fixed, implant-supported prostheses based on the incidence and variety of biologic and technical complications. The etiologies of these complications are also discussed, emphasizing the unpredictability of implant-based prostheses in the oral environment. Materials and Methods: Electronic searches of the MEDLINE (Ovid) database were initially conducted to find articles in English relating to the incidences and/or etiologies of dental implant complications up to May 2006. These articles were then manually searched and potential papers investigated. Electronic and manual searches of 11 peer-reviewed dental journals completed the research strategy, with a hierarchy of evidence-based information established to support this complication-based analysis. Results: Biologic and technical complications appear to be common in all forms of fixed implant-supported dentistry. These complications often jeopardize the functional and/or esthetic features of a given prosthesis, and they occur despite sound prosthetic design and high levels of clinical expertise. Observational studies and systematic reviews dominate this area of the dental literature, leaving the clinician to individually assess the merits of prosthetic retrievability based only on the likelihood of complications and the costs of replacing a permanently cemented prosthesis. These assessments challenge the philosophy of permanent cementation, but there is a need for better, evidence-based information to properly evaluate the costs of prosthetic retrievability against the obvious clinical benefits. Conclusion: The practice of permanently cementing implant-based prostheses may conflict with the likelihood of biologic and technical failure. The retrievability of fixed, implant-supported prostheses is therefore an important consideration in delivering quality, patient-based treatment outcomes.

Purpose: The purpose of this study was to evaluate whether maximum forced inspiratory airflow changes occur by changing the jaw position in Japanese normal subjects and patients with obstructive sleep apnea (OSA) classified by their craniofacial features. Materials and Methods: The subjects included 8 male non-OSA subjects and 15 male patients with OSA whose conditions had been diagnosed with a polysomnographic recording. The OSA subjects were divided into 2 groups by means of a craniofacial (CF) score based on cephalometric variables: a high-score group (CF score >= 4) and a low-score group (CF score £ 3). A case-control design was utilized to assess group differences (control and 2 patient groups). Airflow changes were determined using a spirometer that assessed the velocity of airflow during forced inspiration. Maximum forced inspiratory airflow was measured in 4 positions in all patients. Results: All 3 groups had a significant decrease in their maximum forced inspiratory airflow upon reclining, and there were no significant group differences regarding the magnitude of this change. The OSA subjects returned to baseline measurements more than controls when the jaw was positioned forward, as the jaw was progressively advanced in high CF score subjects. Conclusion: This study suggested that a protrusive jaw position allows more inspiratory airflow to occur in OSA patients compared to controls, and this was significant in the patients with a high CF score.

Purpose: To investigate the association between factors related to the time of wearing complete dentures (CDs) and oral health-related quality of life (OHRQoL) in edentulous patients who maintained a recall. Materials and Methods: OHRQoL was measured using the German version of the Oral Health Impact Profile (OHIP-G) in a convenience sample of 50 edentulous prosthodontic patients (mean age ± SD: 72.5 ± 9.4; age range: 52 to 91 years, 66% women) maintaining a recall 2 to 51 months after CD treatment. The outcome of the study was the sum of OHIP-G item responses (OHIP-G49; range, 0 to 196) that characterized OHRQoL. Exposure variables were (1) time since first treatment with CDs, (2) number of previous CDs, (3) age of present CDs, and (4) age at which first CDs were provided. The association between exposure variables and outcome was investigated using an ordinary least-square regression analysis, controlling for the effects of age. Results: Age of current CDs, time since first CD, number of previous CDs, and the age at which CDs were first provided did not significantly influence OHRQoL. Regression coefficients for each exposure variable were, respectively, 0.0, 95% CI: -0.1 to 0.2; -0.1, 95% CI: -0.4 to 0.3; 0.8, 95% CI: -1.5 to 3.0, and 0.4, 95% CI: -0.1 to 0.8. Conclusion: The response to inevitable anatomic and biologic changes in the oral cavity related to edentulism, denture-wearing, age, and other factors does not necessarily translate rapidly into changes in perceived oral health in patients wearing CDs and maintaining a recall.

Purpose: Clinical, microbiologic, and immunologic comparisons of the peri-implant health in edentulous volunteers wearing long-standing implant-supported ball- or Dolder bar-retained mandibular overdentures were performed. Materials and Methods: Ten age- and gender-matched individuals (mean age, 71 years) with either ball- or bar-retained complete mandibular overdentures, scheduled for an annual implant recall examination, were investigated an average of 7 years after implant placement. Plaque and gingival crevicular fluid samples were obtained from the peri-implant sulcus. The groups were compared with regard to peri-implant probing depth; plaque and bleeding on probing scores; sulcular fluid flow rates; implant stability measurements (Periotest device); relative concentrations of Actinobacillus actinomycetemcomitans, Prevotella intermedia, Fusobacterium nucleatum, Porphyromonas gingivalis, Tannerella forsythensis, and Treponema denticola assessed by polymerase chain reaction analysis; and sulcular concentrations of interleukin-1b and prostaglandin E2, assessed by enzyme-linked immunosorbent assay. Results: No statistically significant differences were found for any of the examined parameters between both study groups. Conclusion: Within the limitations of this study, both ball attachments and Dolder bars can be recommended for overdenture retention, with either one showing satisfying clinical, microbiologic, and immunologic findings in the peri-implant tissues after several years of service in healthy recall patients with good oral hygiene habits.

This study determined the effect of 10 years of water immersion on the properties of fiber-reinforced resin composites (FRC). E-glass and silica fibers were used to reinforce heat-cured and autopolymerized acrylic resin polymers. Control specimens were unreinforced. Test specimens stored in water for up to 10 years were tested by the 3-point test. The flexural strength and elasticity of the specimens decreased during water immersion (P < .001, analysis of variance). After 10 years, the reductions in flexural strength and modulus of E-glass FRC were 24% and 21%, respectively; for silica FRC, reductions were 47% and 46%, respectively; and for controls, reductions were 24% and 11%, respectively. E-glass FRC showed a smaller reduction in strength than silica FRC.

Purpose: Assessments of masticatory performance and occlusal force for wearers of obturator prostheses were performed as clinical objective assessments and reported in an earlier study. The purpose of the present study was to evaluate clinically the chewing function of obturator prosthesis wearers by self-evaluations and to examine their relationship to the objective assessments. Materials and Methods: Twenty patients with maxillofacial obturator prostheses who were having a periodic checkup at the maxillofacial rehabilitation clinic in Kyushu University Hospital were recruited for this study. Chewing function was evaluated by 3 assessment tools: a self-assessment mastication scale, a chewing function score, and a mastication score. In addition, correlations among these assessments and objective tests-ie, masticatory performance and maximum occlusal force-were analyzed by the Spearman rank correlation coefficient. Results: The mean self-assessment mastication scale was 63.2 (SD 31.8), the chewing function score was 54.0 (SD 30.2), and the mastication score was 51.4 (SD 33.3). There was no statistically significant relationship between the self-assessment mastication scale and each objective test. However, there were significant correlations between each semisubjective score-the chewing function score and the mastication score-and masticatory performance. There was no relationship between each semisubjective score and maximum occlusal force. Conclusion: A self-assessment mastication scale was not always in agreement with objective assessments, and assessments made by patients should be taken into consideration when arranging maxillofacial rehabilitation. Conversely, both chewing function and mastication scores corresponded with masticatory performance, and these would be useful as screening tests before performing objective tests.

A 67-year-old woman was referred with a rapidly progressing swelling in the left canine region of the edentulous mandible. Nine months earlier, 2 permucosal implants had been placed in her atrophic anterior mandible. A few weeks after implant placement, an inoperable carcinoma of the lung had been diagnosed. This tumor was treated with a combination of chemotherapy and radiotherapy. After 3 months, the implants were provided with a Dolder bar supporting an overdenture. Subsequently, progressive inflammation developed around the left implant and removal of the implant was necessary. When progressive swelling of the mucosa developed at the previous implant site, the patient was referred to an oral and maxillofacial surgeon. The swelling measured 35 mm in diameter and was biopsied. It was diagnosed as a metastasis of the lung carcinoma to the mandible. The tumor of the jaw was treated with local radiotherapy.

The aim of this prospective clinical trial was to determine the outcome of polyethylene fiber ribbon-reinforced, resin composite post-and-core restorations used as endodontic buildups to support all-ceramic crowns. A total of 42 teeth (31 anterior, 11 posterior) with a mean follow-up time of 35.85 months (range, 10 to 73 months) were treated with 3-mm-wide polyethylene fiber ribbon-reinforced resin composite as post-and-core material. The posts and cores were assessed by clinical and radiographic examination. During the evaluation period, only 1 dentin-cement failure was observed as a post dislodgement after 11 months of clinical service. Performance of polyethylene fiber ribbon post and resin composite core foundation restorations provided clinically satisfactory support for all-ceramic crowns.

Purpose: The effects of 2 chemical retraction agents on gingival blood flow and systemic blood pressure in subjects with healthy gingiva were investigated. Materials and Methods: Thirty volunteer dental students were selected for the study and randomly divided into 2 groups. Aluminium chloride-impregnated cord (right side) and nonimpregnated cord (left side) were placed in the gingival sulcus of group 1. Epinephrine-impregnated cord (right side) and nonimpregnated cord (left side) were placed in group 2. Blood flow in the retracted marginal gingiva was measured by laser Doppler flowmetry, and the systemic blood pressures of subjects were recorded before and after the retraction procedure. Results: A statistically significant decrease in blood flow was observed in group 2, but there was no significant change in gingival blood flow in group 1. A decrease in diastolic blood pressure of the subjects in group 2 was also observed. However, there was no significant change in blood pressure of the subjects in group 1. Conclusion: Gingival retraction affects gingival blood flow temporarily. Epinephrine-impregnated cords can be used safely in patients who have healthy gingiva, if patient stress and gingival trauma are avoided during cord placement.

Purpose: The aim of this study was to compare the cumulative survival rates and the complication rates of established methods of indirect cast posts and cores and direct posts and composite cores over at least 5 years within a retrospective study of patients who received fixed restorations. Materials and Methods: The patients were questioned according to a protocol and were examined clinically and radiologically. Of the 101 patients who were recruited, 72 came for a follow-up examination. Results: Forty-one cast posts and cores and 31 composite cores were examined clinically and radiologically after an average observation period of 8.56 (SD 1.45) years. Four teeth were extracted during the observation period, and 2 more were extracted at the time of the examination. This resulted in cumulative survival rates of 90.2% for cast posts and cores and 93.5% for composite cores. There were 28 complications altogether, consisting of 2 (7.1%) root fractures, 8 (28.6%) teeth with increased probing depths, 3 (10.7%) with increased degrees of mobility, 4 (14.3%) with caries, 9 (32.1%) with periapical radiolucency and/or retrograde filling, and 2 (7.1%) with loss of retention. No statistically significant differences between the 2 methods could be found regarding survival and complication rates. Conclusion: It can be concluded that over an average observation period of 8.56 years the indirect cast post-and-core buildup and the direct composite post buildup can be considered of similar value.

Purpose: This study compared the microtensile bond strength of resin-based cement (Panavia F) to silica-coated, silanized, glass-infiltrated high-alumina zirconia (In-Ceram Zirconia) ceramic in dry conditions and after various aging regimens. Materials and Methods: The specimens were placed in 1 of 4 groups: group 1: dry conditions (immediate testing without aging); group 2: water storage at 37°C for 150 days; group 3: 150 days of water storage followed by thermocycling (3 12,000, 5°C to 55°C); group 4: water storage for 300 days; group 5: water storage for 300 days followed by thermocycling. Results: Group 1 showed a significantly higher microtensile bond strength value (26.2 ± 1 MPa) than the other aging regimens (6.5 ± 1, 6.2 ± 2, 4.5 ± 1, 4.3 ± 1 MPa for groups 2, 3, 4, and 5, respectively) (P < .01). Conclusion: Satisfactory results were seen in dry conditions, but water storage and thermocycling resulted in significantly weaker bonds between the resin cement and the zirconia.

Purpose: The aim of this clinical 2-year follow-up study was to compare the postoperative sensitivity of abutment teeth restored with full coverage restorations retained with either conventional glass-ionomer cement or a new adhesive resin cement containing 4-methacrylolyloxyethyl trimellitate anhydride (4-META). Materials and Methods: Sixty patients received 120 full-coverage restorations on vital abutment teeth, cemented with either a glass-ionomer cement (Ketac-Cem) or a new adhesive resin cement (Chemiace II). A randomized split-mouth design and a patient double-blind data acquisition protocol were used. The teeth were examined before cementation, after 1 week, and after 6, 12, and 24 months. Results: With regard to postcementation sensitivity, a low incidence was observed for both groups. With the adhesive resin cement, little postoperative hypersensitivity was observed after 1 week (13.3%), 6 months (5.9%), 12 months (2.1%), and 24 months (none); results were similar with the conventional glass-ionomer cement Ketac-Cem after 1 week (5.9%), 6 months (5.9%), 12 months (6.4%), and 24 months (none). After 6 months, 2 teeth of the Chemiace II group showed no sensitivity. Endodontic treatment was carried out for these 2 abutment teeth. After 24 months, no cases of postoperative hypersensitivity were recorded for either group. Conclusion: In this study, the incidence of postoperative hypersensitivity after cementation of full-crown restorations with a conventional glass-ionomer cement and a new adhesive resin cement was similar.

Purpose: The objective of this study was to investigate interexaminer reliability in the clinical measurement of the L*C*h* (lightness/value, chroma, hue) values of anterior teeth using a spectrophotometer (Vita Easyshade). Materials and Methods: The basic color of the maxillary right central incisors and canines of 23 subjects was spectrophotometrically determined by 4 clinicians and an experienced user (development manager) of the spectrophotometer. Also, to analyze the effect of different training with the instrument on interexaminer reliability, 2 of the clinicians were instructed in the use of the spectrophotometer by the experienced examiner, whereas the others instructed themselves by studying the operating manual. Results: Agreement between all examiners was acceptable to excellent (intraclass coefficient > 0.4). The mean value of the measured differences for the central incisors of all subjects for L* values was 5 (for C* = 3.8, h* = 2.7 degrees) and for canines, the mean L* was 4.5 (C* = 3, h* = 1.6 degrees). Results from comparison of the 2 different training methods were inconsistent. Agreement with the experienced examiner ranged from not acceptable (C* values for incisors of self-instructed examiners) to excellent. Conclusion: The distribution of the measurements of 1 subject could lead to deviations in color, probably with clinical impact. For canines, the measurements were at least equally reproducible (in some cases significantly more reproducible) compared to central incisors. Because of the small number of examiners and the inconsistent results, it was not possible to reach a definite conclusion about the effect of different training methods on interexaminer reliability.

A self-inflicted gunshot maxillofacial defect was restored with dental implants and various attachments. Following mandibular surgical reconstruction, a fixed full-arch implant-supported prosthesis was fabricated. The maxillary defect was restored with an obturator retained with bar-clip and ball attachments. Crowns with an unfavorable crown-to-root ratio were used to rectify a compromised unilateral interocclusal space. Functional rehabilitation was achieved without any pathologic sequelae and maintained over a 1-year observation period. Provision of a fixed implant-retained mandibular prosthesis opposing a specific design for a maxillary obturator provided short-term and optimistic prognosis in the management of a serious traumatic injury.

The aim was to evaluate the influence on the stress distribution patterns in and the magnitude of stresses on fixed partial dentures (FPDs) under different anatomic and design conditions. Three-dimensional finite element models of posterior 3-unit all-ceramic FPDs were created with and without periodontal ligaments, with different radii of curvature at the embrasure area, and in a curve shape with a periodontal ligament. The model with a periodontal ligament showed 40% higher stress values compared to the no-ligament model. A smaller radius of curvature resulted in 20% to 40% higher stress values. The curved model increased stress values at the distal connector by 65% compared to the straight model. Support by teeth, occlusal curvature, and a small radius of curvature at the embrasure area negatively affect stress distribution patterns in the connector area of all-ceramic FPDs.