Facial Versus Skeletal Landmarks for Anterior-Posterior Diagnosis in Orthognathic Surgery and Orthodontics: Are They the Same?

PURPOSE: The purpose of this investigation was to evaluate diagnostic agreement in anterior-posterior (AP) categorization of the maxilla and mandible between a skeletal-landmark analysis and a facial-landmark analysis for treatment planning of orthognathic surgery and orthodontics. MATERIALS AND METHODS: This retrospective, consecutive case series of adult patients who presented to the Mayo Clinic orthodontic department compared maxillary and mandibular AP diagnoses. Steiner's analysis of the sella-nasion-A point angle and sella-nasion-B point angle was used for a skeletal-landmark diagnosis. Element II of Andrews' 6 elements of orofacial harmony was used for a facial-landmark diagnosis. Both diagnoses were categorized as either deficient, optimal, or excessive for each jaw. Categorization of the skeletal landmark was determined by normative data, whereas the facial landmark provides a customized categorization unique to each individual. RESULTS: Weighted κ statistics were completed to test agreement between the categories determined by the skeletal and facial landmarks. The maxilla showed poor agreement, and the mandible showed slight agreement. CONCLUSIONS: No agreement was found for AP categorization of the maxilla and mandible between skeletal-landmark and facial-landmark analyses. Most mandibles were diagnosed as retrognathic by the facial landmark, whereas most were diagnosed as optimal by the skeletal landmark. When the 2 landmarks disagreed, the facial landmark defined the optimal position farther anterior. The landmark chosen for diagnosis will impact the optimal jaw position and can affect orthognathic and orthodontic outcomes.

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.

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.

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).