Books

Purpose: To examine the behavior and function of human gingival fibroblasts growing on healing abutments with or without laser-textured topography. Materials and Methods: Human primary gingival connective tissue fibroblasts were cultured on healing abutments with machined or laser-textured (Laser-Lok, BioHorizons) surfaces. Cellular and molecular responses were evaluated by a variety of tests, including cell density assay (WST-1), fluorescence microscopy, real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and detachment tests. Results: The machined surface showed monodirectional traces and scratches from milling, whereas the laser-textured surface showed a distinct morphology consisting of monodirectional mesoscale channels (15-μm pitch) and woven oblique microridges formed within the channels. There were no differences in initial fibroblast attachment, subsequent fibroblast proliferation, or collagen production between the machined and laser-textured surfaces. Fibroblasts growing on a laser-textured surface were found to spread in one direction along the mesochannels, while cells growing on machined surfaces tended to spread randomly. Fibroblasts on laser-textured surfaces were 1.8 times more resistant to detachment than those on machined surfaces. An adhesive glycoprotein (fibronectin) and transmembrane adhesion linker gene (integrin β-1) were upregulated on laser-textured surfaces. Conclusions: The increased fibroblast retention, uniform growth, and increased transcription of cell adhesion proteins compellingly explain the enhanced tissue-level response to laser-created and hybrid-textured titanium surfaces. These results provide a cellular and molecular rationale for the tissue reaction to this unique surface; in addition, they support its extended use, from implants and healing abutments to diverse prosthetic components where enhanced soft tissue responses would be desirable.  Keywords: Laser-Lok, microchannels, abutments, implant, soft tissue attachment, laser-textured

The functional outcomes related to treating patients afflicted with tooth loss are an important hallmark in substantiating prosthodontic intervention. The Oral Rehabilitation Outcomes Network (ORONet) conducted two international workshops to develop a core set of outcome measures, including a functional domain. The process followed the general format used in the Outcome Measures in Rheumatology (OMERACT) workshops to develop consensus for clinical outcome measures in arthritis research, which included: developing a comprehensive list of potential outcomes in the literature; submitting them to a filter for validity, clinical discrimination, and feasibility; and ranking those measures meeting all the filter criteria for relative value. The search was conducted to include functional assessments of speech, swallowing, mastication, nutrition, sensation, and motor function as they relate to dental implant therapies. This literature review surveyed 173 papers that produced some result of these descriptors in the functional domain. Of these, 67 papers reported on functional assessments and further defined objective and subjective outcomes. Many of these results were patient-perceived improvements in function, while others were objective assessments based on established methodologies and instruments. Objective evaluations of masticatory function and speech may meet criteria for validity and discriminability for selected interventions, but are generally not feasible for routine use in clinical care settings. The current recommendation is to employ a well-validated survey instrument that covers mastication and speech, such as the Oral Health Impact Profile (OHIP-14, short form), recognizing that patient perceptions of function may differ from objective ability.

Consensus regarding outcomes of the treatment of tooth loss, especially the psychologic outcomes, is needed to guide discovery of best practices and enable a better understanding of patient management for this chronic condition. This paper presents the findings of the ORONet Psychological Working Group for prosthodontics and aims to identify psychologic outcomes with properties deemed critical to meet clinical trial and clinical practice needs for the future. References obtained using a PubMed/Medline search were reviewed for clinical outcomes measures of interest. Clinical outcomes measures were judged relative to the criteria of truth, discrimination, and feasibility. Of the psychologic outcome measures identified in this systematic review, only the OHIP-14 was thought to be suitable for use in general practice and multi-institutional outcome registries and clinical trials. Development of clinically useful psychologic outcomes for future use could benefit from developmental methods and tools outlined in the patient-related outcomes field of clinical care.

Purpose: A systematic literature review was conducted to identify the types of economic measures currently used in implant prosthodontics and determine the degree to which cost of care is considered in the context of any positive outcome of the care provided. Materials and Methods: A literature search was conducted using the following set of terms plus some additional hand searching: "dental implants" (Mesh) AND ("cost") OR "maintenance" OR "healthcare policy" OR "access to care" OR "third party" OR "economic") AND (("1995/01/01"[PDat]:'2009/12/31"[PDat]) AND (Humans[Mesh]) AND (English[lang])). Results: After a review of the 466 titles and abstracts identified by the search, 18 articles were accepted for further consideration, as some attempt at economic outcome measures was made. An additional four articles were identified by hand searching. The 22 accepted articles were grouped into four basic categories: (1) measure of costs of treatment (direct, indirect, and maintenance costs), (2) cost-effectiveness mathematical modeling applied to simulate the lifetime paths and cost of treatment, (3) cost-effectiveness analysis/costminimization, and (4) willingness-to-pay, willingness-to-accept. Attempts at determining the costs of treatment varied widely. When the OMERACT filters were applied to the various measures it was felt that discrimination and/or feasibility was a problem for most of the current economic outcome measures. Conclusions: Measures of cost-benefit, cost-effectiveness, and cost-utility are currently the gold standard; however, feasibility of such analyses is an issue. Collaboration with health economists to guide future research is highly recommended.

The published literature describing clinical evidence used in treatment decisionmaking for the management of tooth loss continues to be characterized by a lack of consistent outcome measures reflecting not only clinical performance but also a range of patient concerns. Recognizing this problem, an international group of clinicians, educators, and scientists with a focus on prosthodontics formed the Oral Rehabilitation Outcomes Network (ORONet) to promote strategies for improving health based on comprehensive, patient-centered evaluations of comparative effectiveness of therapies for oral rehabilitation. An initial goal of ORONet is to identify outcome measures for prosthodontic therapies that represent multiple domains with patient relevance, are amenable to utilization in both institutional and practice-based environments, and have established validity. Following a model used in rheumatology, the group assessed the prosthodontic literature, with an emphasis on implantbased therapies, for outcomes related to longevity and functional, psychologic, and economic domains. These systematic reviews highlight a need for further development of standardized outcomes that can be integrated across clinical and research environments.

The Oral Rehabilitation Outcomes Network (ORONet) Longevity Working Group undertook a search of the literature from 1995 to 2009 on randomized controlled trials related to longevity of osseointegrated implants. Outcomes measures used in these studies were identified and subjected to the OMERACT component criteria of truth, validity, and feasibility. Through this process, it was a challenge to identify clinical outcomes measures that fully met the criteria. An attenuated version of the component criteria was applied, and clinical measures were identified for implant outcomes, prosthetic outcomes, and indices. A recommendation on standardized reporting periods was also presented for future consideration. The endpoint of the evaluation process is to develop consensus on clinical outcomes measures that can be applied across broad populations for osseointegrated implant care. The present ORONet initiative represents a beginning toward continual improvement and consensus development for clinical outcomes measures for osseointegrated implants.

Purpose: The capability of micro-computed tomography (µCT) for quantitative analysis of peri-implant bone has not been previously addressed. This study aimed to establish and validate a method to use this technique for 3-dimensional bone-implant integration profiling. Materials and Methods: Unthreaded cylindric implants with a dual acid-etched surface were placed into the right femurs of 7 Sprague-Dawley rats. Two weeks postimplantation, the femurs were harvested and measured with a desktop micro-tomographic scanner with an isotropic resolution of 8 µm. To validate the µCT outcome, ground histologic sections and corresponding CT slices were compared with respect to bone morphometry. Results: Bone-implant integration profiles assessed by µCT revealed that the percentage of cancellous bone gradually increased with proximity to the implant surface, while the percentage of cortical bone was not affected by proximity to the implant. Using the optimized segmentation threshold, the bone configuration in the µCT images corresponded to that observed in the histologic sections. The correlation between µCT and histology was significant for cortical (r = 0.65; P .05) and cancellous bone (r = 0.92; P .05) at distances of 24 to 240 µm from the implant surface, but no significant correlation was found for the area from 0 to 24 µm from the surface. Discussion and Conclusion: The results support the usefulness of µCT assessment as a rapid, nondestructive method for 3-dimensional bone ratio measurements around implants, which may provide new perspectives for osseointegration research. Further study is necessary, however, to address the inherent metallic halation artifact, which potentially confounds peri-implant bone assessment. Keywords: dental implants, histomorphometry, micro-computed tomography, Osseointegration

Purpose: To compare the dimensional accuracy of implant framework castings from an argon vacuum casting machine with those from a centrifugal casting machine. Materials and Methods: Three 4 3 10-mm external hex-type implants (3i/Implant Innovations) were embedded in an acrylic resin block 7 mm apart, with a 2 mm offset of the middle implant. Eight reference points were marked on the implant collars. Twenty implant bar frameworks were waxed with UCLA abutments, invested with a ringless system, and subjected to the same thermal cycle. Ten wax patterns were cast in gold alloy using an oxygen-propane torch and centrifugal casting system; 10 were cast using an argon vacuum casting machine (KDF; Denken). The White 1-screw technique was applied after sequentially tightening the mesial and distal abutment screws to 10 Ncm. Fit of the implant framework castings was evaluated by measuring the marginal opening between the casting and implant at the reference points. These measurements were averaged and statistically compared for differences. Results: The mean marginal openings at the most distant measuring locations from the tightened retaining screw at location 1 was between 44 to 48 µm for the centrifugal system compared to between 28 to 32 mm for KDF (P .01). For screws tightened at location 3, the mean marginal openings at the most distant measuring locations were between 40 to 51 mm for the centrifugal system compared to between 27 to 29 µm for KDF (P .01). Discussion: In comparison with the centrifugal casting and oxygen-propane system, the argon vacuum system was more accurate and user friendly and less technique-sensitive. Conclusion: The argon vacuum casting machine tested produced more accurate, better fitting implant-supported prosthesis frameworks than a conventional centrifugal casting system. The "1-screw" method of evaluating casting fit was most effective when either of the prostheses' end screws were tightened. Keywords: argon vacuum casting machine, centrifugal casting machine, implant frameworks, implant-prosthesis fit

Purpose: An analysis of retrospective data was conducted to establish the survival rates of osseointegrated implants used to retain orbital, nasal, and auricular prostheses over a 14- year period and to recommend guidelines in the restorative treatment of such facial defects. Materials and Methods: Included in this study were all patients who received implant-retained prostheses for auricular, nasal, or orbital defects from 1987 to 2001 in the Maxillofacial Clinics at the UCLA and City of Hope Medical Centers. Data were obtained from patient charts. Two methods were used to determine survival rates: (1) the percentage of the total exposed implants that survived was determined, and (2) lifetable analysis was used to calculate cumulative survival rates at different time intervals. Results: A total of 207 implants were placed in 72 patients, and 182 implants had been uncovered. During the study period, 35 implants failed to integrate, and the survival rate for all exposed implants was 80%. Auricular implants showed the highest survival rate (95%), and orbital implants showed the lowest survival rate (53%). The lifetable analysis demonstrated a cumulative 6-year survival rate of 92% for auricular implants and 87% for piriform/nasal implants. In contrast, the survival rate for orbital implants showed a steady downward trend and reached 59% at 66 months. Conclusion: It is possible to achieve high survival rates of implants in the auricular and piriform/nasal sites through careful presurgical and radiographic planning. The less favorable long-term survival of implants in the orbital rim, especially at irradiated sites, requires further study.