Daniel A. Assad

Survival of Dental Implants in Irradiated Head and Neck Cancer Patients: A Retrospective Analysis

PURPOSE To study the long-term survival of dental implants placed in irradiated bone in subjects who received radiation for head and neck cancer. MATERIALS AND METHOD A retrospective chart review was conducted for all patients who received dental implants following radiation treatment for head and neck cancer between May 1, 1987 through July 1, 2008. Only patients irradiated with a radiation dose of 50 Gy or greater and those who received dental implants in the irradiated field after head and neck radiation were included in the study. The associations between implant survival and patient/implant characteristics were estimated by fitting univariate marginal Cox proportional hazards models. RESULTS A total of 48 patients who had prior head and neck radiation had 271 dental implants placed during May 1987 to July 2008. The estimated survival at 1, 5, and 10 years was 98.9%, 89.9%, and 72.3%, respectively. Implants placed in the maxilla were more likely to fail than implants placed in the mandible (p = .002).There was also a tendency for implants placed in the posterior region to fail compared with those placed in the anterior region (p =.051). CONCLUSION Dental implants placed in irradiated bone have a greater risk for failure. Survival is significantly influenced by the location of the implant (maxilla or mandible, anterior or posterior).

Survival of dental implants in native and grafted bone in irradiated head and neck cancer patients: a retrospective analysis.

AIM To study the long-term survival of dental implants placed in native or grafted bone in irradiated bone in subjects who had received radiation for head and neck cancer. MATERIALS AND METHODS A retrospective chart review was conducted for all patients who received dental implants following radiation treatment for head and neck cancer between May 1, 1987 and July 1, 2008. Only patients irradiated with a radiation dose of 50 Gy or greater and those who received dental implants in the irradiated field after head and neck radiation were included in the study. The associations between implant survival and patient/implant characteristics were estimated by fitting univariate marginal Cox proportional hazards models. RESULTS A total of 48 patients who had prior head and neck radiation had 271 dental implants placed during May 1987-July 2008. There was no statistically significant difference between implant failure in native and grafted bone (P=0.76). Survival of implants in grafted bone was 82.3% and 98.1% in maxilla and mandible, respectively, after 3 years. Survival of implants in native bone in maxilla and mandible was 79.8% and 100%, respectively, after 3 years. For implants placed in the native bone, there was a higher likelihood of failure in the maxilla compared to the mandible and there was also a tendency for implants placed in the posterior region to fail compared to those placed in the anterior region. CONCLUSION There was no significant difference in survival when implants were placed in native or grafted bone in irradiated head and neck cancer patients. For implants placed in native bone, survival was significantly influenced by the location of the implant (maxilla or mandible, anterior or posterior).

Relationship between Systemic Bone Mineral Density and Local Bone Quality as Effectors of Dental Implant Survival

PURPOSE This study aimed to assess (1) the relationship of systemic bone mineral density (BMD) and osteoporotic status with the surgeons subjective assessment of local jawbone quality, and (2) whether the surgeons subjective assessment of local jawbone quality is a predictor of implant failure. MATERIALS AND METHODS A retrospective analysis of 2,867 dental implants placed in 645 patients was accomplished. The surgeons assessment of bone quality at the time of dental implant placement was recorded. Of those, 208 patients with 701 implants had BMD data available within 3 years. Statistical analyses were conducted to determine relationships between BMD, osteoporotic status, and local jawbone quality and to determine the relationship between local jawbone quality and implant survival. RESULTS There was no association between systemic BMD and the surgeons assessment of bone quality (p =.52) nor between osteoporotic status and the surgeons assessment of local jawbone quality (Spearman rank correlation coefficient=0.08). Additional retrospective analysis revealed implants placed in moderate- (hazard ratio=1.67; p=.043) or poor-quality (HR=3.45, p< .001) bone (surgeons assessment) were significantly more likely to fail than implants placed in good-quality bone. CONCLUSION Systemic BMD and osteoporotic status are not associated with local jawbone quality. Implants placed in good-quality bone, as assessed subjectively by the surgeon at the time of implant placement, have significantly better survival characteristics than implants placed in moderate-/poor-quality bone.

Survival of turned and roughened dental implants in irradiated head and neck cancer patients: A retrospective analysis

STATEMENT OF PROBLEM Dental implants placed into previously radiated fields in survivors of head and neck cancer can demonstrate survival rates that are less than optimal. Understanding this behavior may assist with treatment planning in accordance with expected survival rates in these patients. PURPOSE The purpose of this study was to compare the survival of implants with turned and roughened surfaces placed in patients who had previously received head and neck radiation, and to identify factors associated with implant failure. MATERIAL AND METHODS The records of 48 patients who had prior head and neck radiation and had 271 dental implants placed between May 1987 and July 2008 were examined. All of the implants were placed in a previously irradiated field dosed to at least 50 Gy. Implant survival was estimated using the Kaplan-Meier method and univariate Cox models with robust standard errors were fitted to evaluate the association between patient/implant factors and implant failure. RESULTS There were 62 implants placed in the maxilla (32 roughened, 30 turned) and 209 implants (107 roughened, 102 turned) placed in the mandible. The 5-year implant survival rate for implants placed in the maxilla was 72.6% for turned implants and 87.5% for roughened implants. For implants placed in the mandible, the 5-year survival rate was 91.7% for turned implants and 100% for roughened implants. Among implants with a turned surface, implants were more likely to fail if they were placed in the maxilla (P=.008) and if the diameter was ≤3.75 mm (P=.002). CONCLUSIONS Implants with turned surfaces were 2.9 times more likely to fail compared to the roughened dental implants, although the difference did not reach statistical significance. For implants with turned surfaces, there was a tendency for implants in the maxilla to fail more frequently compared to the mandible. Implants with turned surfaces had a higher likelihood of failure in the posterior region than in the anterior region. For implants with roughened surface there was no significant association between implant survival and location of the implant, type of bone, or length or diameter of the implant.

Evaluation of Fracture Resistance in Aqueous Environment of Four Restorative Systems for Posterior Applications. Part 1

PURPOSE The goals of this study were to: (1) establish a range of the performance of four restorative systems for posterior single-tooth crowns under single load to fracture submerged in an aqueous environment, (2) identify restorative system(s) of interest to be examined in the second study phase under sliding contact step-stress fatigue as full-contour anatomically appropriate single posterior tooth restoration(s), (3) establish a range for loading/testing for phase 2. MATERIALS AND METHODS Forty specimens (n = 10/group) of 2 mm uniform thickness were tested. Group 1: monolithic lithium disilicate IPS e.max Press; group 2: IPS e.max ZirPress, 0.8 mm zirconia core with 1.2 mm pressed veneering porcelain; group 3: IPS e.max ZirPress, 0.4 mm zirconia core with 1.6 mm pressed veneering porcelain; group 4: IPS InLine PoM. Specimens were bonded to a block of polycast acrylic resin on a 30° sloped surface with resin cement. Specimens were axially single loaded to failure while submerged under water. RESULTS There was a statistically significant difference (p < 0.001) in failure load among the four restorative systems. Lithium disilicate showed a mean failure load similar to mean maximum posterior bite forces (743.1 ± 114.3 N). IPS e.max Zirpress with a 0.4 mm zirconia core exhibited the lowest mean failure load (371.4 ± 123.0 N). CONCLUSION Fracture resistance of monolithic lithium disilicate in an aqueous environment is promising and requires second phase testing to evaluate the potential of various thicknesses appropriate for posterior single tooth applications. Doubling the IPS e.max Zirpress zirconia core from 0.4 mm to 0.8 mm increased the fracture resistance of this restorative system threefold.

Peripheral T-Cell lymphoma manifested as gingival enlargement in a patient with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in adults and is associated with increased risk of malignancy. T-cell lymphoma associated with CLL has never been reported. The case report presents a unique case of peripheral T-cell lymphoma on the gingiva of a patient with CLL. A 66-year-old man with a history of CLL was referred to the Mayo Clinic, Department of Dental Specialties, for evaluation of swelling in the upper left posterior sextant. An intraoral examination revealed a soft tissue swelling in the area of teeth number 13 and 15, including the present edentulous ridge between number 13 and 15. An incisional biopsy was performed on the palatal aspect of tooth No. 15 and submitted for histologic evaluation. The histopathology revealed proliferation of large atypical cells beneath the epithelium, positive for antigens CD2, CD3, Beta-F1, TIA-1, and Granzyme B consistent for a diagnosis of a peripheral T-cell lymphoma. A team approach including the hematologist, general dentist and periodontist resulted in timely referrals leading to an early diagnosis and early intervention and treatment.

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.