Risk-adapted dental care prior to intensity-modulated radiotherapy (IMRT).

BACKGROUND: At the Clinic for Radiation Oncology at the Zurich University Hospital (UniversitätsSpital Zürich [USZ]), head-and-neck tumor (HNT) patients have been treated with intensity-modulated radiotherapy (IMRT) since 01/2002 (n 〉 800). This method causes less damage to normal tissues adjacent to the tumor, and thus it was possible in the head/neck region to markedly reduce the rate of osteoradionecrosis (ORN), in addition to reducing the rate of severe xerostomia. Based on these results, risk-adapted dental care (RaDC) was adopted by our clinic as the standard mode of pre-IMRT dental treatment. The guidelines as formulated by Grötz et al. were respected. ORN prophylaxis is one of the most important goals of pre-radiotherapy dental care, and the ORN rate is a measurable parameter for the efficacy of dental care, given a certain radiation technique. The aim of the present study was therefore to evaluate the efficacy of RaDC as reflected by the ORN rate of our IMRT patients. MATERIALS AND METHODS: IN August 2006, RaDC was clinically implemented and has been used for all HNT patients prior to IMRT since then. Before that (01/2002-07/2006), dental restorations were performed according to the usual procedure. RESULTS: The rate of grade-2 ORN was similar in the conventionally treated and RaDC groups (2% and 1%, resp.); grade-3 ORN had not occurred by the time the analysis was conducted. As expected, fewer extractions were performed in the RaDC cohort (no extractions in 47% of the RaDC/IMRT cohort vs. 27% in the IMRT cohort receiving conventional dental care). CONCLUSION: After considerably less invasive dental treatment, no higher-grade ORN occurred and no ORN-related jaw resections were required. Based on the present data, risk-adapted minimally invasive dental care is recommended before IMRT.

[Recommendations for dental care prior to intensity-modulated radiotherapy (IMRT). Adaptation of the University Hospital Zurich (USZ) guidelines]. / Empfehlung für die Zahnsanierung vor intensitäts-modulierter Radiotherapie (IMRT). UniversitätsSpital Zürich (USZ)-Richtlinien-Anpassung.

This article is aimed to inform about the recently performed adjustments of the established standard procedures for pre-radiotherapeutic dental care (GROTZ 2003; Shaw et al. 2000) on intensity modulated radiation therapy (IMRT) at the Department of Radiation Oncology, University Hospital Zurich (USZ). The adjustments described base on prospectively assessed results and clinical observations of more than 300 head and neck cancer patients treated with definitive or postoperative IMRT at the own institution. In order to explain the clinical differences between conventional radiation techniques and IMRT, a brief introduction section addresses characteristics of IMRT delivery, optimization of normal tissue sparing, and resulting improved normal tissue tolerance (Fig. 1a-c). In conclusion, careful adjustments of pre-treatment dental care as proposed (Tab. I) are recommended for IMRT patients. This requires close case-related interdisciplinary cooperation between the referring radiation oncologist and the dentist or dental care centre, respectively. The depicted sketches (Fig. 2) are thought to get completed by the radiation oncologist, in order to inform the dentist about topographic risk areas/levels for radiation-induced late effects.

A new optical method to evaluate three-dimensional volume changes of alveolar contours: a methodological in vitro study.

OBJECTIVES: The aim of this study was to evaluate the reproducibility and the accuracy of volumetric measurements of specimens imitating localized alveolar ridge defects using an optical three-dimensional (3D) system. MATERIAL AND METHODS: Eight pairs of specimens (five with a cuboid and three with a geometrically complex form) were used for the measurements. Each of them imitated a pre-operative ridge defect and a corresponding surgically corrected post-operative situation. The true volume differences between two corresponding specimens were either assessed by a mechanical 3D coordinate measuring machine or by computer calculation (controls). For the test measurements, an optical 3D system with a newly developed software for volume measurements was utilized. The volumes of the specimen pairs were captured and the data digitized. The volume differences between the simulated pre- and post-operative situations were calculated by subtracting the two values obtained. The accuracy of the optical 3D system was assessed comparing the test and the control values. The difference between these values described the systematic error of the test method. The reproducibility was evaluated by calculating the coefficients of variation of repeated test volume measurements. Descriptive statistics were applied. RESULTS: The accuracy of the optical 3D system was very high with differences between test and control measurements never exceeding 1.5%. The systematic error of the test measurements was consistently below 2.5 mm3. The reproducibility of the measurements showed very low coefficients of variation ranging from 0.05% to 0.5%, indicating excellent reproducibility. CONCLUSIONS: The tested optical 3D system showed excellent accuracy and high reproducibility for measuring volume differences between specimens imitating localized alveolar ridge defects before and after augmentation procedures.

Survival rate of zygomatic implants in atrophic or partially resected maxillae prior to functional loading: a retrospective clinical report.

PURPOSE: The purpose of this article was to evaluate the survival rate of 34 remote anchorage implants placed in 18 patients from placement to uncovering, prior to any prosthetic loading. MATERIALS AND METHODS: A total of 18 patients (9 women and 9 men with a mean age of 63 years) who required rehabilitation with a fixed prosthesis because of severely atrophic maxillae (including 1 patient who had undergone primary and secondary cleft lip and palate repair), traumatic maxillary bone loss, and maxillectomy procedures received 1 or 2 zygomatic implants and 2 to 4 standard maxillary dental implants. The survival rate of the 34 zygomatic implants from placement to uncovering was investigated. Aspects of the placement technique or postoperative complications related to surgical procedures likely to affect the implant failure rate were detected and critically discussed. RESULTS: Osseointegration was evaluated using the reverse torque test and percussion after uncovering. Only 1 patient (5.6%) sustained postoperative clinical complications during the evaluation period which resulted in the loss of both zygomatic implants (5.9%). CONCLUSION: Although the handling of this anchorage implant system is somewhat complex, and the design has certain shortcomings, it might be an alternative to more extensive bone augmentation procedures. However, rehabilitation of partially or completely edentulous patients with fixed implant-supported prosthesis is only feasible when 2 to 4 standard implants are placed in the anterior maxilla and splinted with the zygomatic implants.