A cost-minimization analysis of measures against metallic dental restorations for head and neck radiotherapy

Magnetic resonance imaging investigations in patients with metallic dental prosthesis: "The associated dilemma for medical fraternity and the dentist's role"

Background

Interdisciplinary referrals for dental examination in hospital setups are common before radiotherapy, kidney transplants, or magnetic resonance imaging (MRI). The patients who walk in could be random patients with metallic or porcelain-fused-to-metal prostheses done elsewhere but might require an opinion before the MRI. This leaves quite a responsibility on the consulting dentist to green signal the procedure. There is a lack of evidence in the literature, to confirm the absence of any untoward consequence during such MRI, which might leave the dentist in dilemma. Dental materials' magnetic behavior raises concern regarding whether they are 100% nonferromagnetic; furthermore, the examining dentist might be unaware of the metal used (Co-Cr, Ni-Cr, or trace elements). Clinicians may also come across full-mouth rehabilitated patients with multiple crown-bridge prostheses or metallic superstructure for implant prostheses. Research in the area leaves many unanswered questions because most studies have evaluated artifacts during MRI and are in vitro. Titanium is considered to be safe due to its paramagnetic behavior, whereas the literature does not rule out the probability of dislodgment of other porcelain fused to metal (PFM) prostheses. Due to less reported literature there exists dilemma to ascertain MRI in these patients. An online Google Search, PubMed, and gray literature portray the ambiguity associated with metal and PFM crowns and their magnetic behavior during MRI. Most studies were associated with the artifacts caused during MRI and methods of reducing them under in vitro situations. The concern for dislodgment has also been expressed in a few reports.

Technique

Certain steps of a pre-MRI checkup and an innovative technique have been discussed to assure patient safety during the MRI.

Conclusion

The technique explained is inexpensive and a quick aid that can be executed before the investigation.

Clinical and Research Implications

There is a need to study and understand the magnetic behavior of Co-Cr and Ni-Cr crowns in the presence of various MRI strengths.

The Relationship between the Contouring Time of the Metal Artifacts Area and Metal Artifacts in Head and Neck Radiotherapy

(1) Background: The impacts of metal artifacts (MAs) on the contouring workload for head and neck radiotherapy have not yet been clarified. Therefore, this study evaluated the relationship between the contouring time of the MAs area and MAs on head and neck radiotherapy treatment planning. (2) Methods: We used treatment planning computed tomography (CT) images for head and neck radiotherapy. MAs were classified into three severities by the percentage of CT images containing MAs: mild (<25%), moderate (25−75%), and severe (>75%). We randomly selected nine patients to evaluate the relationship between MAs and the contouring time of the MAs area. (3) Results: The contouring time of MAs showed moderate positive correlations with the MAs volume and the number of CT images containing MAs. Interobserver reliability of the extracted MAs volume and contouring time were excellent and poor, respectively. (4) Conclusions: Our study suggests that the contouring time of MAs areas is related to individual commitment rather than clinical experience. Therefore, the development of software combining metal artifact reduction methods with automatic contouring methods is necessary to reducing interobserver variability and contouring workload.

Comparison of methods for the handling of metallic dental restorations before head and neck radiotherapy

PURPOSE

During head and neck radiotherapy, backscatter from metallic dental restorations (MDRs) causes oral mucositis. Currently, two MDR handling methods are used: the replacement of MDRs with provisional restorations (MDR removal) and fabrication of dental spacers before radiotherapy. We compared the effects of these two methods on the incidence of oral mucositis during head and neck radiotherapy.

METHODS

We enrolled 76 patients with MDRs who underwent radiotherapy for head and neck cancer between April 2016 and March 2020. We set grade 2 oral mucositis as an outcome. After adjustment of all covariates using the propensity score (PS), we analyzed the data using a Cox proportional hazards model. In addition, subgroup analysis was performed by stratifying the data into quintiles based on the PS.

RESULTS

For the incidence of grade 2 oral mucositis due to head and neck radiotherapy, the hazard ratio for the MDR removal group relative to the dental spacer group was 0.344 (95% confidence interval, 0.121-0.980; P = 0.046). Subgroup analysis showed that the hazard ratio for the MDR removal group was 0.339 (95% confidence interval, 0.122-0.943; P = 0.038).

CONCLUSION

The results suggest that MDR replacement is superior to dental spacer fabrication in reducing the incidence of oral mucositis during head and neck radiotherapy, although MDR removal carries several associated risks.