A Custom Mouthpiece With Lip Bumper for Osteoradionecrosis Risk Reduction After Carbon-Ion Radiation Therapy for Adenoid Cystic Carcinoma of the Lip

Abstract

Purpose

A custom mouthpiece with lip bumper for carbon-ion radiotherapy (CIRT) of tumors of the lip was developed with the goal of reducing the incidental exposure of the maxilla.

Methods and Materials

The mouthpiece was manufactured using a thermoplastic ethylene-vinyl acetate copolymer. This was employed in a patient with primary adenoid cystic carcinoma of the right lip without invasion of the maxilla. To evaluate spacer utility, the volume of maxilla receiving more than 50 Gy (relative biological effectiveness, V50) with and without the spacer was calculated using dose-volume histogram (DVH) analysis in a simulation study and subsequently treated.

Results

In the simulation study, DVH analysis demonstrated a 46% dose reduction in the high-dose area of the maxilla with mouthpiece usage (V50 = 2.21 mL) compared to non-usage (V50 = 4.11 mL). The mouthpiece was well-tolerated. Eight years after CIRT, no late dermatitis, oral mucositis, or osteoradionecrosis was observed.

Conclusions

A custom-made mouthpiece with a lip bumper successfully reduced the incidental exposure of the maxilla during CIRT.