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.

PurposeTo retrospectively investigate empirical relative biological effectiveness (RBE) for mandible osteoradionecrosis (ORN) in head and neck (H&amp;N) cancer patients treated with pencil-beam-scanning proton therapy (PBSPT).MethodsWe included 1,266 H&amp;N cancer patients, of which, 931 patients were treated with volumetric-modulated arc therapy (VMAT) and 335 were treated with PBSPT. Among them, 26 VMAT and 9 PBSPT patients experienced mandible ORN (ORN group), while all others were included in the control group. To minimize the impact of the possible imbalance in clinical factors between VMAT and PBSPT patients in the dosimetric comparison between these two modalities and the resulting RBE quantification, we formed a 1:1 case-matched patient cohort (335 VMAT patients and 335 PBSPT patients including both the ORN and control groups) using the greedy nearest neighbor matching of propensity scores. Mandible dosimetric metrics were extracted from the case-matched patient cohort and statistically tested to evaluate the association with mandibular ORN to derive dose volume constraints (DVCs) for VMAT and PBSPT, respectively. We sought the equivalent constraint doses for VMAT so that the critical volumes of VMAT were equal to those of PBSPT at different physical doses. Empirical RBEs of PBSPT for ORN were obtained by calculating the ratio between the derived equivalent constraint doses and physical doses of PBSPT. Bootstrapping was further used to get the confidence intervals.ResultsClinical variables of age, gender, tumor stage, prescription dose, chemotherapy, hypertension or diabetes, dental extraction, smoking history, or current smoker were not statistically related to the incidence of ORN in the overall patient cohort. Smoking history was found to be significantly associated with the ORN incidence in PBSPT patients only. V40Gy[RBE], V50Gy[RBE], and V60Gy[RBE] were statistically different (p&lt;0.05) between the ORN and control group for VMAT and PBSPT. Empirical RBEs of 1.58(95%CI: 1.34-1.64), 1.34(95%CI: 1.23-1.40), and 1.24(95%: 1.15-1.26) were obtained for proton dose at 40 Gy[RBE=1.1], 50 Gy[RBE=1.1] and 60 Gy[RBE=1.1], respectively.ConclusionsOur study suggested that RBEs were larger than 1.1 at moderate doses (between 40 and 60 Gy[RBE=1.1]) with high LET for mandible ORN. RBEs are underestimated in current clinical practice in PBSPT. The derived DVCs can be used for PBSPT plan evaluation and optimization to minimize the incidence rate of mandible ORN.

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.