Mean Oral Cavity Organ-at-Risk Dose Predicts Opioid Use and Hospitalization during Radiotherapy for Patients with Head and Neck Tumors.

BACKGROUND: Approximately 75% of all head and neck cancer patients are treated with radiotherapy (RT). RT to the oral cavity results in acute and late adverse events which can be severe and detrimental to a patient's quality of life and function. The purpose of this study was to explore associations between RT dose to a defined oral cavity organ-at-risk (OAR) avoidance structure, provider- and patient-reported outcomes (PROs), opioid use, and hospitalization. METHODS: This was a retrospective analysis of prospectively obtained outcomes using multivariable modeling. The study included 196 patients treated with RT involving the oral cavity for a head and neck tumor. A defined oral cavity OAR avoidance structure was used in all patients for RT treatment planning. Validated PROs were collected prospectively. Opioid use and hospitalization were abstracted electronically from medical records. RESULTS: Multivariable modeling revealed the mean dose to the oral cavity OAR was significantly associated with opioid use (p = 0.0082) and hospitalization (p = 0.0356) during and within 30 days of completing RT. CONCLUSIONS: The findings of this study may be valuable in RT treatment planning for patients with tumors of the head and neck region to reduce the need for opioid use and hospitalization during treatment.

Viewpoint: Periprosthetic joint infection and dental antibiotic prophylaxis guidelines.

The purpose of this viewpoint is to provide a framework that is used within the Mayo Clinic to align recommendations from infectious disease experts, dental specialists, and orthopedic surgeons with regards to need for antibiotic prophylaxis prior to invasive dental procedures.

Implementation of a Scholarly Activity Program in a Small Academic Medical Center Department.

Small departments within academic medical centers have fewer numbers of clinicians, less time devoted to research, and fewer staff with senior faculty academic ranks available as mentors. This report describes the rationale behind Mayo Clinic's Department of Dental Specialties' scholarly activity program, implemented to combine mentorship with scholarship provided in a variety of formats. Program objectives focused on providing mentorship, disseminating existing scholarship, and bringing a diversity of scholarly activities into departmental mainstream.

Accuracy of complete-arch implant impression made with occlusal registration material.

STATEMENT OF PROBLEM: Which impression material, impression tray type, and implant impression technique combination produces the most accurate complete-arch impression is unclear. PURPOSE: The purpose of this in vitro study was to compare the implant impression accuracy of a completely edentulous arch made with addition silicone occlusal registration material and an open tray with the implant impression accuracy of other conventional impression techniques. MATERIAL AND METHODS: A master cast was fabricated from Type IV gypsum with four 3.8-mm diameter implants with internal hexagon located in the area of mandibular canines and first molars. Impressions (N=60) were made from the master cast using the 6 techniques investigated: group B-OC-N with occlusal registration impression material (B), open custom tray (OC), and nonsplinted impression pins (N); group B-OS-N with occlusal registration impression material (B), open plastic perforated stock tray (OS), and nonsplinted impression pins (N); group PE-OC-N with polyether medium-body impression material (PE), open custom tray (OC), and nonsplinted impression pins (N); group PE-OC-S with polyether medium-body impression material (PE), open custom tray (OC), and impression pins splinted (S) with autopolymerizing resin cut after 17 minutes and reconnected; group PE-CC-N with polyether medium-body impression material (PE), closed custom tray (CC), and nonsplinted impression pins (N); group PVS-CS-N with simultaneous double-mix polyvinyl siloxane impression material (PVS), closed stock perforated metal tray (CS), and nonsplinted impression pins (N). Type IV gypsum casts were fabricated 24 hours after making the impressions. A computerized numerical control 3D coordinate measuring machine was used to measure the absolute differences of the distances between the centroids of the 4 implants among the casts produced and the distances measured at the master cast. The Kruskal-Wallis test was used to determine differences among the experimental groups (α=.05). The Mann-Whitney U post hoc analysis was used for all group combinations. RESULTS: No significant differences were found between the test groups B-OC-N and PE-OC-S, which were more accurate than the other groups. Group B-OS-N resulted in the least accurate impressions of all experimental groups. Group PE-OC-S resulted in more accurate impressions than the PE-OC-N group. No statistically significant differences were found between groups PE-OC-N and PE-CC-N or between groups PVS-CS-N and PE-CC-N. CONCLUSIONS: For complete edentulism, the use of silicone occlusal registration material with an open custom tray and nonsplinted impression pins resulted in impressions as accurate as those produced with PE open custom tray with splinted impression pins. These 2 techniques resulted in more accurate impressions than the other 4 techniques studied.

WITHDRAWN: Interventions for replacing missing teeth: partially absent dentition.

BACKGROUND: Management of individuals presenting with partial loss of teeth is a common task for dentists. Outcomes important to the management of missing teeth in the partially absent dentition should be systematically summarized. This review recognizes both the challenges associated with such a summarization and the critical nature of the information for patients. OBJECTIVES: To assess the effects of different prostheses for the treatment of partially absent dentition in terms of the following outcomes: long-term success, function, morbidity and patient satisfaction. SEARCH METHODS: We searched the Cochrane Oral Health Group's Trials Register (to 21 March 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE via OVID (1950 to March 2011) and EMBASE via OVID (1980 to March 2011). There were no restrictions regarding language or date of publication. We contacted several authors to identify non-published trials. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing different methods (including the design and materials used) of treating partial edentulism, with clinically relevant outcomes, were included in this review. Trials reporting only surrogate outcomes, such as plaque accumulation or gingival volume, were excluded from this review. DATA COLLECTION AND ANALYSIS: Two review authors independently carried out the screening of eligible studies, assessment of dimensions of quality of trials, and data extraction. Results were expressed as mean differences for continuous data, risk ratios for dichotomous outcomes, and hazard ratios with 95% confidence intervals for time-to-event data. MAIN RESULTS: Twenty-one trials met the inclusion criteria for this review. Twenty-four per cent of these were assessed as being at high risk of bias and the remainder were at unclear risk of bias. The clinical heterogeneity among the included studies precluded any attempt at meta-analysis. There was insufficient evidence to determine whether one type of removable dental prosthesis (RDP) was better or worse than another. With fixed dental prostheses (FDPs), there was no evidence that high gold alloys are better or worse than other alloys, nor that gold alloys or frameworks are better or worse than titanium. There is insufficient evidence to determine whether zirconia is better or worse that other FDP materials, that ceramic abutments are better or worse than titanium, or that one cement was better or worse than another in retaining FDPs. There is insufficient evidence to determine the relative effectiveness of FDPs and RDPs in patients with shortened dental arch or to determine the relative advantages of implant supported FDPs versus tooth/implant supported FDPs. AUTHORS' CONCLUSIONS: Based on trials meeting the inclusion criteria for this review, there is insufficient evidence to recommend a particular method of tooth replacement for partially edentulous patients.

Relationship between Selective Serotonin Reuptake Inhibitors and Risk of Dental Implant Failure.

PURPOSE: To identify associations between implant failure and selective serotonin reuptake inhibitor (SSRI) medication use in a cohort of consecutive patients receiving dental implants during a 20-year period. MATERIALS AND METHODS: A retrospective review was conducted of all patients who received at least 1 dental implant from January 1, 1995, through December 31, 2014, assessing their history of SSRI use, active SSRI use, and SSRI use during follow-up with implant failure. Cox proportional hazards regression models assessed associations between demographic characteristics and SSRI use with implant failure, and outcomes were summarized with hazard ratios (HRs) and 95% confidence intervals (CIs). Follow-up SSRI use was analyzed with time-dependent covariates. RESULTS: During the study period, 5456 patients received their first implant (median age, 53 years). The median duration of follow-up was 5.3 years (interquartile range, 2.3-10.2 years) for the 4927 patients who did not have implant failure. For the 529 patients who had implant failure, it occurred at a median of 0.5 years. After adjusting for age, sex, and era of implant, history of use of the SSRI sertraline was associated with an increased risk of implant failure among all patients (hazard ratio [HR], 1.60; 95% CI, 1.15-2.23; p = 0.006) and among the subset of patients with a history of SSRI use (HR, 1.64; 95% CI, 1.07-2.52; p = 0.02). CONCLUSIONS: In the population reviewed, a history of sertraline use was associated with a 60% greater risk of implant failure; however, active SSRI use at the time of implant placement or during follow-up was not significantly associated with an increased risk of implant failure.

Risk of Dental Implant Failure Associated With Medication Use.

PURPOSE: The probability of achieving important clinical outcomes is an increasingly important factor for patients considering various treatment options for tooth loss. For oral reconstruction involving dental implants, the patient-specific risks of implant failure may be influenced by the patient's medication profile. The purpose of this study was to identify associations between dental implant failure and medication use in a consecutive series of patients seen from October 1983 through December 2014 at the Department of Dental Specialties, Mayo Clinic (Rochester, Minnesota). MATERIALS AND METHODS: In this patient-level analysis, demographic, implant-specific, and medical profile data were abstracted from a prospective clinical database and individual medical records and used to determine the time to first implant failure. Implant failure-free survival at the patient level was estimated using the Kaplan-Meier method. Associations of demographic characteristics and medication use with implant failure were evaluated by using Cox proportional hazards regression models and summarized with hazard ratios and 95% confidence intervals. RESULTS: In the 31-year study period, 6358 patients received their first dental implant (median age, 53 years). The median follow-up duration of the 5645 patients whose implants did not fail was 5.8 years, and 713 patients had implant failure (median, 0.6 years). All associations were adjusted for age, sex, and era of implantation because these features strongly influence medication use and implant failure. After adjustment, no medication increased the risk of implant failure in the cohort; specifically, medication use at the time of implant placement or starting a medication after implant placement did not increase the risk of implant failure. Among the medications used at the time of implant placement, corticosteroids were associated with a reduced risk of implant failure (hazard ratio, 0.82; 95% CI, 0.67-0.99; p = 0.04). This association was not seen when corticosteroids were started after implant placement. CONCLUSION: In the population studied, medication use was not associated with an increased risk of dental implant failure.

Early Implant Failure Associated With Patient Factors, Surgical Manipulations, and Systemic Conditions.

PURPOSE: Systematic monitoring of important clinical outcomes is increasingly important for health-care decision making, especially in the context of continuous quality improvement. Dental implant failure within the first year (early failure) has been previously shown to be more common than subsequent failure. The purpose of this study was to identify associations between early implant failure and patient factors, surgical manipulations, and systemic conditions. MATERIALS AND METHODS: The authors retrospectively identified the records of consecutive adult patients with dental implants seen between 2000 and 2014 in the Department of Dental Specialties, at the Mayo Clinic. Demographic, surgical, and medical data were extracted from the database and individual medical records to determine time to first implant failure. Cox proportional hazards regression models were used to assess associations of demographic, surgical, and systemic conditions with implant failure during the first year post-implantation, summarized as hazard ratio (HR) (95% confidence interval [CI]). RESULTS: Among 8540 implants identified during the study period, 362 (4.2%) failed within the first year of placement at a mean (SD) of 129 (96) days after placement. On univariate analysis, most candidate predictors were not shown to influence first-year failure. Preplacement surgical manipulations associated with increased early implant failure were bone augmentation only (HR, 1.45; 95% CI, 1.02-2.05; p = 0.04), socket preservation (HR, 2.67; 95% CI, 1.33-5.38; p = 0.006), and xenogenic material (HR, 2.12; 95% CI, 1.11-4.04; p = 0.02). Alveoloplasty only at placement was associated with decreased early implant failure (HR, 0.33; 95% CI, 0.17-0.65; p = 0.001). Overall, 318 implants (3.7%) had surgical complications within the first year of placement at a mean (SD) of 110 (114) days after placement; any surgical complication was significantly associated with early implant failure (hazard ratio, 15.84; 95% CI, 11.10-22.61; p < 0.001). After adjustment for age, sex, and implant era, no single or multiple medical condition(s) and no single or multiple medication(s) increased patient risk of implant failure in the first year after placement. CONCLUSIONS: These findings support a targeted effort to reduce the incidence of surgical complications to reduce early failure of dental implants.

Association Between Early Implant Failure and Prosthodontic Characteristics.

PURPOSE: To identify associations between early implant failure and prosthodontic characteristics that could be used to guide subsequent continuous quality improvement efforts of patient care. MATERIALS AND METHODS: An implant-level analysis was performed in which data were abstracted from a prospective clinical database of all adult patients treated with implants and followed up from January 2000 through December 2014 at the Department of Dental Specialties at Mayo Clinic in Rochester, Minnesota. These data were used to determine time to implant failure. Associations between prosthodontic characteristics and early implant failure were evaluated with Cox proportional hazards regression models and summarized with hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Among 8762 implants in 2787 patients, 395 (4.5%) failed within the first year of placement at a mean (SD) of 127 (97) days (range, 2-364 days). Univariable analysis showed no associations between early implant failure and use of a cover screw, prosthesis, or definitive or provisional prosthesis at implant placement. Three of 25 single crowns failed, and use of a single crown was significantly associated with early implant failure (HR, 3.94; 95% CI, 1.08-14.35; P = 0.04). This study identified no significant associations between prosthodontic characteristics identified after implant placement and early implant failure. CONCLUSIONS: Use of a prosthesis at implant placement, use of a definitive or provisional prosthesis, and early mechanical complications were not associated with increased risk of early implant failure. Quality improvement efforts should focus on aspects of decision making that aim to decrease surgical complications.

Consistency of Dental Hygiene Therapy Utilizing Various Dental Hygiene Instrumentation and Its Effect on Peri-implant Health and Survival of Dental Implants: A Retrospective Study.

PURPOSE: The purpose of this retrospective study was to provide practice-based evidence to determine if the consistency of dental hygiene therapy, despite utilizing instrumentation literature that has proven to cause alterations to implant surfaces, affects peri-implant health or survival. MATERIALS AND METHODS: The study sample comprised patients with implant-supported full-arch fixed dental prostheses who were distributed into two groups. The consistent hygiene group patients had dental hygiene therapy at a minimum biannually and were exposed to at least three dental hygiene instrument materials. The inconsistent hygiene group patients had dental hygiene therapy at a minimum once every 3 to 10 years and were exposed to at least three dental hygiene instrument materials. Years of survival free of soft tissue pathology and/or implant failure were estimated. Continuous features were summarized with medians, interquartile ranges (IQRs), and ranges; categorical features were summarized with frequency counts and percentages. RESULTS: Among 48 patients in the consistent hygiene group, 11 patients experienced soft tissue pathology or implant failure at a median of 11.3 years; among 99 patients in the inconsistent hygiene group, 17 patients experienced soft tissue pathology or implant failure at a median of 4.8 years. The survival free of soft tissue pathology or implant failure rate at 5 years was 94% for the consistent hygiene group and 91% for the inconsistent hygiene group. The survival free of soft tissue pathology or implant failure rate at 20 years was 70% for the consistent hygiene group and 79% for the inconsistent hygiene group (P = .91). CONCLUSION: Although no statistical differences were found between the groups, this practice-based evidence suggests more consistent dental hygiene therapy increases the median in years in which soft tissue pathology or implant failure is present.

Association of Systemic Conditions with Dental Implant Failures in 6,384 Patients During a 31-Year Follow-up Period.

PURPOSE: Outcome research has become an increasingly important form of clinical evidence for making health care decisions, including oral health considerations in the field of dentistry. In oral reconstruction involving dental implants, the risk of implant failure may be influenced by a patient's underlying medical condition. To identify associations, implant failure and systemic conditions or diseases were studied in a consecutive series of patients who received dental implants from October 1, 1983, to December 31, 2014, in the Department of Dental Specialties at Mayo Clinic in Rochester, Minnesota. MATERIALS AND METHODS: Data were abstracted from a prospective clinical database and electronic health records for patients' demographic, implant-specific, and medical profiles to determine time to first implant failure. Survival free of implant failure at the patient level was estimated by using the Kaplan-Meier method. Associations of demographic and systemic characteristics with implant failure were evaluated by using Cox proportional hazards regression models and summarized with hazard ratios and 95% confidence intervals. RESULTS: The patient cohort consisted of 6,358 patients with a median age of 53 years at placement of the first implant. A total of 713 patients experienced implant failure at a median of 0.6 years. Among the 5,645 patients who did not experience implant failure, the median duration of follow-up was 5.8 years. More than 20 systemic diseases or conditions were identified for assessment, of which 15 comprised more than 50 patients and five comprised more than 500 patients. All associations were adjusted for age, sex, and era of implant, given the strong influence of these features on implant failure. After adjustment, no systemic disease or condition was shown to increase the risk for implant failure in the population and setting studied. CONCLUSION: Patients considering oral reconstruction involving implants in the medical setting studied do not appear to risk implant loss because of systemic conditions or diseases.

Effect of the American Heart Association 2007 Guidelines on the Practice of Dental Prophylaxis for the Prevention of Infective Endocarditis in Olmsted County, Minnesota.

OBJECTIVE: To determine the adherence of dental providers to the 2007 American Heart Association (AHA) infective endocarditis prevention guidelines regarding antibiotic drug administration before invasive dental procedures. PATIENTS AND METHODS: The study included all adults (≥18 years old) with a moderate-risk (MR) or high-risk (HR) cardiac condition who received dental care at participating dental offices from January 1, 2005, through June 1, 2015, in Olmsted County, Minnesota. Data collected included the date and type of dental procedure performed and receipt of antibiotic prophylaxis (AP). RESULTS: A total of 1351 patients underwent 8854 dental visits at participating dental offices during the study period; 1236 patients had an MR cardiac condition and 115 had an HR condition. The percentage of visits in which antibiotic drugs were used for indicated dental procedures in the MR group declined from 64.6% before to 8.6% after publication of the 2007 AHA guidelines (P<.001); for the HR group, AP declined from 96.9% before to 81.3% after publication of the guidelines (P=.02). CONCLUSION: In this historical cohort in Olmsted County there was a statistically significant reduction in AP in the MR group before invasive dental procedures. In addition, there was an unanticipated significant reduction in AP in the HR group after publication of the 2007 AHA guidelines. These findings can be used to provide feedback and education to medical and dental professionals who are involved in decision making regarding the use of dental prophylaxis for their patients.

Linking medical and dental health record data: a partnership with the Rochester Epidemiology Project.

PURPOSE: The purpose of this project was to expand the Rochester Epidemiology Project (REP) medical records linkage infrastructure to include data from oral healthcare providers. The goal of this linkage is to facilitate research studies examining the role of oral health in overall health and quality of life. PARTICIPANTS: Eight dental practices joined the REP between 2011 and 2015. The REP study team has linked oral healthcare information with medical record information from local healthcare providers for 31 750 participants who have resided in Olmsted County, Minnesota. Overall, 17 718 (56%) participants are women, 14 318 (45%) are 40 years of age or older and 26 090 (82%) are white. FINDINGS TO DATE: A first study using this new information was recently completed. This resource was used to determine whether the 2007 guidelines from the American Heart Association affected prescription rates of antibiotics to patients with moderate-risk cardiac conditions prior to dental procedures. The REP infrastructure was used to identify a series of patients diagnosed with moderate-risk cardiac conditions by the local healthcare providers (n=1351), and to abstract antibiotic prescriptions from dental records both pre-2007 and post-2007. Antibiotic prescriptions prior to dental procedures declined from 62% to 7% following the change in guidelines. FUTURE PLANS: Dental data from participating practitioners will be updated on an annual basis, and new dental data will be linked to patient medical records. In addition, we will continue to invite new dental practices to participate in the REP. Finally, we will continue to use this research infrastructure to investigate associations between oral and medical health, and will present findings at conferences and in the scientific literature.

Three-dimensional printing of large nasal septal perforations for optimal prosthetic closure.

BACKGROUND: Since 1972, patients with large nasal perforations, who were symptomatic, and who were not candidates for surgery, had the option of custom prosthetic closure at Mayo Clinic. Although septal prostheses have helped many patients, 27% of pre-1982 patients chose not to keep the prosthesis in place. Two-dimensional computed tomography (CT) sizing resulted in more of the patients choosing to retain the prosthesis. The introduction of three-dimensional (3-D) printing to the sizing process offered the potential of further improved retention by refinement in prosthesis fit. OBJECTIVE: To describe the fabrication of nasal septal prostheses by using 3-D printing for sizing and to compare the retention rate of 3-D-sized prostheses with those that used previous sizing methods. METHODS: Twenty-one consecutive patients who had placement of septal prostheses sized by using 3-D printed templates were studied. CT image data were used to print 3-D templates of the exact shape of the patient's septal perforation, and medical-grade silastic prostheses were fabricated to fit. In four cases, the 3-D printed template allowed preoperative surgical simulation. Metrics collected included prosthesis retention; symptoms, including intranasal crusting and epistaxis; and previous prosthetic closure failures. RESULTS: Twenty of the twenty-one patients had improvement in symptoms. The mean diameter of the perforations was 2.4 cm; the mean closure time by the end of the study period was 2.2 years. All but two patients chose to keep their prosthesis in place, for a retention rate of 90%. Seven patients with successful closure had failed previously with prior prosthesis sized without the current 3-D printing methodology. This 90% retention rate exceeded the previous rates before the introduction of 3-D sizing. CONCLUSION: Sizing done by 3-D printing for prosthetic closure of nasal septal perforations resulted in a higher retention rate in helping patients with these most-challenging nasal septal perforations.

Evidence and the practice of prosthodontics: 20 years after EBD introduction.

Prosthodontics has a rich history related to the principles embedded in evidence-based health care. This paper reviews the evidence-based prosthodontics activity over the past 3 decades. It also discusses the impact of health care reform on evidence-based medicine as it relates to broader context of care outcomes. Finally, the value associated with an Evidence Stewardship emphasis in prosthodontics is presented. This emphasis suggests that combining evidence from clinical trials with evidence from clinical practice environments best equips clinicians for the management of patients in the future. Adoption of a strategic Evidence Stewardship direction is an extended commitment to change that recognizes health care reform aims and seeks to be an accountable provider group in the broader health care arena. The vision to form a representative network of prosthodontic practitioners that augments a commitment to Cochrane "clinical trial" data demonstrates a responsibility to professional transparency about who we are, adds value for patients and oral health care providers, impacts teachers and students in dental education, and provides a measure of care accountability unique in dentistry.

External versus internal abutment connection implants: a survey of opinions and decision making among experienced implant dentists in Japan.

Internal connection implants have been attracting attention in recent years leading to their being adopted for many implant systems and an increase in market share over other connections. However, internal connection implants have only been used clinically for a short period of time resulting in few clinical studies investigating outcomes and a lack of comparative clinical evidence to support their use over external hex systems at this time. Given the fact that clinical evidence is lacking regarding implant connection performance comparisons, it is important to understand what information clinicians use to choose between systems. The purpose of this study regarding implant decision-making was to ask clinicians to provide subjective evaluations of internal connection implants, in comparison with external connection implants. The survey was constructed to cover four aspects of interest; general responder information, surgical procedures and experience, prosthodontic treatments and outcomes, and implant complications. The dentists' responses indicated that internal connection implants are as user-friendly as external hex implants with respect to implant surgery, but they are favored for prosthodontic handling because impression coping and abutment placement are felt to be easier. In addition, it was revealed that dentists strongly feel that there is a lack of biological and prosthodontic evidence to support the use of internal connection implants. The findings reveal the responding clinicians recognize that they often make decisions without compelling evidence to favor one system over another. Decisions are often based on perceived ease of use or third party (colleague or manufacturer) input. For future investigations, we will seek to better understand the relative influence and validity of all forms of information used (especially third party input), as well as what barriers exist to clinicians' use of more evidence based data.

Evaluation of fracture resistance in aqueous environment under dynamic loading of lithium disilicate restorative systems for posterior applications. Part 2.

PURPOSE: The goals of part 2 of the study presented here were 1) to assess whether there is a difference in failure mode of different thicknesses (2.0, 1.5, 1.0, and 0.5 mm) of anatomically standardized full contour monolithic lithium disilicate restorations for posterior teeth, and 2) to assess if there is a difference among various crown thicknesses when these restorations are subjected to dynamic load forces common for posterior teeth. MATERIALS AND METHODS: Four groups (n = 10), each with a different thickness of anatomically appropriate all-ceramic crowns, were to be tested as established from the statistical analysis of the preliminary phase. Group 1: 2.0 mm; group 2: 1.5 mm; group 3: 1.0 mm; group 4: 0.5 mm. The specimens were adhesively luted to the corresponding die, and underwent dynamic cyclic loading (380 to 390 N) completely submerged in an aqueous environment until a failure was noted by graphic recording and continuous monitoring. RESULTS: There was a statistically significant difference of the fatigue cycles to failure among four groups (p < 0.001; Kruskal-Wallis test). The mean number of cycles to fail for 2.0 mm specimens was 17 times more than the mean number of cycles to fail for 1.0 mm specimens and 1.5 times more than the mean number of cycles to fail for 1.5 mm specimens. The 0.5 mm specimens failed with one cycle of loading. A qualitative characteristic noted among the 2.0 mm specimens was wear of the area of indenter contact followed by shearing of the material and/or crack propagation. CONCLUSION: Based on the findings of this study, it may be reasonable to consider a crown thickness of 1.5 mm or greater for clinical applications of milled monolithic lithium disilicate crowns for posterior single teeth.

Practice-based clinical evaluation of ceramic single crowns after at least five years.

STATEMENT OF PROBLEM: Long-term practice-based clinical evaluations of various contemporary ceramic crown restorations from multiple practitioners are limited. PURPOSE: The aims of this study were to evaluate the clinical performance of ceramic single crowns and to identify factors that influence their clinical performance. MATERIAL AND METHODS: Ceramic single crowns that had been placed at the Mayo Clinic and in function since 2005 were identified and included in the study. The restorations were examined clinically, radiographically, and with photographs. Modified United States Public Health Services criteria were used for the clinical evaluation. The ceramic systems evaluated were bilayer and monolayer. RESULTS: Fifty-nine patients (41 women, 18 men) with 226 single teeth and implants restored with single ceramic crowns were identified. The mean duration from insertion date to study examination date was 6.1 years. Thirteen restorations (6%) were replaced at a mean 3.3 years after insertion date (range, 0.1-6.1 years). Estimated replacement-free survival rates (95% confidence interval [CI]; number of teeth/implants still at risk) at 5 years after insertion date were 95.1% (95% CI, 92.2-98.1; 153) and at 10 years were 92.8% (95% CI, 89.1-96.8; 8). The most common reason for replacement was fracture to the core of posterior layered ceramic crowns. The most commonly used luting agent was resin-modified ionomer cement. Most restorations exhibited clinically acceptable marginal integrity, shade, no caries recurrence, and no periapical pathology. CONCLUSIONS: The clinical performance of ceramic single crowns at 5 and 10 years supports their application in all areas of the mouth. With the majority of fractures to the core occurring early in the lifetime of layered ceramic posterior crowns, consideration of other monolithic ceramic systems for posterior crowns is advised.