A high frequency of osteoradionecrosis after hyperfractionated radiotherapy (RT) of head and neck tumours led to a detailed analysis of risk factors in the dental, surgical, and radiotherapeutic areas. 168 patients with oral cancer were analysed retrospectively. 19% of them had been irradiated primarily and 81% postoperatively. 116 patients received a total dose mostly ranging from 60 Gy to 70 Gy to the ICRU 29 reference point (daily single dose 2 Gy). 52 patients were treated hyperfractionally with two daily fractions of 1.2 Gy per day, 4 h minimum apart and a total dose 82.8 Gy. Dental findings could be evaluated in 126 patients. Factors were checked for prognostic significance for osteoradionecrosis (ORN). Dose dependency was computed using a PROBIT analysis. Dental status before radiotherapy was generally poor (mean 11/32 teeth present, of these 1 was dead, 2.4 carious, 2.4 loose, 0.3 destroyed). On average, six teeth (range 0-27 teeth) had to be extracted. In one-third of the patients bone surgery was necessary. ORN occurred in 8.6% of the patients treated conventionally but in 22.9% of those treated hyperfractionally (p = 0.029). Biologically effective dose (p = 0.032) and deep paradontitis (p = 0.034) proved to be significant risk factors for ORN. PROBIT analysis showed a steadily rising dose dependency of the ORN frequency after conventional radiotherapy. Using total doses up to 70 Gy the frequency of ORN was 8.6%. Dose escalation using hyperfractionation led to an intolerable ORN frequency (22.9%) where a short interfraction interval was a significant factor. The use of this dose fractionation was therefore discontinued in 1992.

ObjectivesDental status, dental treatment procedures and radiotherapy dosage as potential risk factors for an infected osteoradionecrosis (IORN) in patients with oral cancers: Retrospective evaluation of 204 patients treated in two observation periods of approximately ten years each.Patients and methodsIn group A, 90 patients were treated in the years 1993-2003, in group B 114 patients in the years 1983-1992 (data in brackets). All patients had histopathologically proven squamous cell cancers, mainly UICC stages III and IV. 70% (85%, n.s.) had undergone surgery before radiotherapy. All patients were referred to the oral and maxillofacial surgeon for dental rehabilitation before further treatment.Radiotherapy was performed using a 3D-conformal technique with 4-6MV photons of a linear accelerator (Co-60 device up to 1987). The majority of patients were treated using conventional fractionation with total doses of 60-70 Gy in daily fractions of 2 Gy. Additionally, in group A, hyperfractionation was used applying a total dose of 72 Gy in fractions of 1.2 Gy twice daily (time interval > 6 hours). In group B, a similar schedule was used up to a total dose of 82.8 Gy (time interval 4-6 hours). 14 (0) patients had radiochemotherapy simultaneously. After therapy, the patients were seen regularly by the radiooncologist and – if necessary – by the oral and maxillofacial surgeon. The duration of follow-up was 3.64 years (5 years, p = 0.004).ResultsBefore radiotherapy, the dental health status was very poor. On average, 21.5 (21.2, n.s.) teeth were missing. Further 2.04 teeth (2.33, n.s.) were carious, 1.4 (0.3, p = 0.002) destroyed.Extractions were necessary in 3.6 teeth (5.8, p = 0.008), conserving treatment in 0.4 (0.1, p = 0.008) teeth. After dental treatment, 6.30 (4.8, n.s.) teeth remained.IORN was diagnosed after conventionally fractionated radiotherapy in 15% (11%, n.s.), after hyperfractionation in 0% (34%, p = 0.01).ConclusionWithin more than 20 years there was no improvement in dental status of oral cancer patients. Extensive dental treatment procedures remained necessary. There was an impressive reduction of the IORN frequency in patients treated in a hyperfractionated manner probably resulting from a dose reduction and an extension of the interfraction time.

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