Thomas J. Salinas

Implant-Supported Single Crowns Predictably Survive to Five Years with Limited Complications

SELECTION CRITERIA An electronic MEDLINE search was conducted to identify cohort studies, prospective or retrospective, describing clinical performance of implant-supported single crowns. Manual searches of bibliographies from full-text articles and related reviews were conducted using numerous scientific journals. Studies were included if the mean follow-up time was at least 5 years, if articles were published in the English or German language, if patients were physically examined, and if study details were sufficient for data extraction. Of the initial 3601 studies identified, only 26 were selected. No randomized control trials were identified. KEY STUDY FACTOR The 5-year survival and complications of implant-supported single crowns. MAIN OUTCOME MEASURES The primary outcome measure in this study was survival of endosseous implants when used to support single crowns. In addition, the clinical performance of soft tissue (peri-implantitis) and hard tissue (bone level) was documented. Clinical complications of a biomechanical nature were recorded relative to fracture of restorative materials. Poissons regression models were used to estimate failure and complication rates at 5 years. MAIN RESULTS A systematic review of the scientific literature identified 26 studies from which data were extracted (1558 placed implants). Meta-analysis identified survival of implants used to support and retain single crowns at 96.8% (95% confidence interval [CI]: 95.9%-97.6% after 5 years). The survival rate of the single crown restorations documented in 13 studies was 94.5% (95% CI: 92.5%-95.9%) with a significantly higher survival rate when metal ceramic crowns were used in comparison with all ceramic crowns (95.4% CI: 93.6%-96.7%; 91.2% CI: 86.8%-94.2%). Soft tissue complications, including peri-implantitis, were observed in 9.7% of the single crowns, whereas bone loss exceeding 2 mm was identified on 6.3% of the implants over the 5-year study. Prosthetic or abutment screw loosening was observed in 12.7%of the restoration and screw fracture occurred in 0.35%. Although only 7 of the 26 studies reported esthetic complications, the cumulative effects of esthetic complications approached 9% at 5 years. CONCLUSIONS From the presented data it may be concluded that 5-year survival of implant-supported single crowns is high, although biologic and mechanical complications are anticipated.

Clinical Evaluation of Implants in Radiated Fibula Flaps

PURPOSE The success of osseointegrated implants in the radiated fibula flap used for mandibular reconstruction is variable, and there are few long-term data available in the literature. The purpose of this study is to evaluate implant success in radiated fibula flaps and the native mandible after ablative tumor surgery. MATERIALS AND METHODS The medical records of 44 patients who underwent resection and reconstruction of the mandible from 1994 to 2006 were reviewed retrospectively. A total of 206 implants were placed; 144 were placed in a fibula flap, and 92 were placed in the native mandible. Before implant placement, 22 patients (50%) received adjuvant tumoricidal doses of radiation therapy (>6,000 cGy). All patients who received radiation received a standard regimen of 20 preoperative and 10 postoperative hyperbaric oxygen treatments. The follow-up period ranged from 4 to 108 months (mean, 41.1 months). Comparisons were made between groups regarding long-term implant success based on several variables. RESULTS Implants were considered to be successful if there was no radiographic evidence of peri-implant bone loss and if they were clinically osseointegrated. Of 206 implants, 31 failed, with an overall success rate of 85%. The success rate of implants placed in fibula flaps was 82.4%, and the success rate in native mandibles was 88%. Most of the failures in the fibula (90%) occurred within the first 6 months after implant placement, whereas most of the failures in the mandible occurred after 6 months. The cumulative survival rate was 91.9%, and there was no difference in survival between implants placed in the fibula versus the native mandible or depending on whether the patient received radiation therapy. CONCLUSION Acceptable long-term implant success rates may be achieved in the radiated mandible with vascularized fibula flap reconstruction.

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).

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 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.

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.

Medial Femoral Periosteal Microvascular Free Flap: A New Method for Maxillary Reconstruction

Maxillary defects may arise from ablative tumor surgery or severe maxillofacial trauma. Contemporary maxillofacial reconstruction must consider both functional and esthetic concerns to optimize reconstruction, with the ultimate goal of prosthetic dental rehabilitation. Several techniques are available for maxillary reconstruction, including nonvascularized bone grafting from the iliac crest, and an entire gamut of microvascular reconstructive options. The choice of reconstruction should be based on the nature of the defect, and the patient’s tolerance for donor-site morbidity. Several microvascular techniques were described for extensive composite maxillary defects: most notably, the free fibula osteocutaneous 1 and deep circumflex iliac artery free flap. 2 Alternative approaches for moderate to large composite maxillary defects include soft tissue-only reconstruction for defect obliteration without bone reconstruction, using myorotational flaps such as the temporoparietal rotational flap, and free-tissue transfer with the rectus abdominus or latissimus dorsi muscle. Obliteration of the soft-tissue defect after maxillectomy may isolate the antral and nasal contents for the oropharynx, but renders prosthetic dental rehabilitation difficult, with limited functional outcomes. Some guidelines were presented, as based on physical and anatomic requirements for prosthodontic reconstruction. 3 The options are limited for small, recalcitrant, or difficult to obturate alveolar defects of the maxilla. Various studies showed that vascularized bone grafts can be used successfully to treat cases of persistent nonunion. 4-6 These studies showed the biological and mechanical benefits of vascularized bone grafts compared with nonvascular grafts. Vascularized grafts accelerate healing because they are capable of preserving osteocytes, replacing deficient bone, revascularizing ischemic bone, and increasing bone mass with diminished osteopenia after transfer. 7,8 Limited composite defects or nonunion sites, even in the presence of preexisting infection, may be unsuitable for autologous corticocancellous bone grafts, despite gaps of less than 5 cm. For such situations, vascularized bone grafts have become the standard of care. 9

Functional Outcomes for Clinical Evaluation of Implant Restorations

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.