The effect of head-fractioned teletherapy on pulp tissue

Head and neck radiotherapy effects on the dental pulp vitality and response to sensitivity tests. A systematic review with meta-analysis

BACKGROUND

There is no consensus whether radiotherapy for head and neck cancer (HNC) could induce pulp necrosis. Therefore, a systematic review of clinical studies is necessary.

OBJECTIVES

To evaluate the evidences on radiotherapy for HNC and pulp status.

METHODS

A systematic search of articles published until November 2021 was performed in the MEDLINE/PubMed, Cochrane Library, Web of Science (All Databases), Scopus, EMBASE and Open Grey databases. The eligibility criteria were based on the PICOS strategy, as follows: (P) vital teeth of adult patients with intraoral and/or oropharyngeal cancer; (I) radiotherapy; (C) control group or values of the same tooth before radiotherapy (basal values); (O) pulpal status after radiotherapy; (S) clinical studies. The Cochrane Risk Of Bias In Non-randomised Studies - of Interventions (ROBINS-I) tool was used to assess the quality of the included studies. Meta-analyses were performed using fixed and random effects. The overall quality of evidence was assessed through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool.

RESULTS

Six studies were included for qualitative analysis. Five were classified as serious risk of bias and one as moderate risk of bias. Four studies reported altered pulp responses to cold thermal test after radiotherapy initiation. Meta-analyses were performed using three included studies. From these, all were included in the meta-analysis for pulp response values to cold sensitivity test immediately after radiotherapy initiation (risk ratio: 0.00[CI:0.00, 0.02], P < 0.00001; I² = 0%); and two in the meta-analysis for pulp response values to cold sensitivity test after 4-5 months of radiotherapy (risk ratio: 0.01[CI: 0.00. 0.06], P < 0.00001; I² = 0%). Two reported progressively higher readings to pulp response in the electrical test after radiotherapy initiation (mean difference: -11.46[-13.09, -9.84], P < 0.00001; I² = 68%) and at all periods evaluated. Two studies demonstrated a pulp oxygen saturation (SpO₂ ) decrease at the end of radiotherapy; and increase after 4-6 months of radiotherapy beginning. And other demonstrated normal dental pulp SpO₂ 4 to 6 years after treatment. GRADE analysis presented a moderate certainty of evidence.

DISCUSSION

This review verified that radiotherapy for HNC causes significant alterations on the dental pulp responses, but does not seem to induce pulp necrosis. Significant limitations regarding controlling for confounding factors, classification of interventions and measurement of outcomes were verified, evidencing the need for well-designed studies.

CONCLUSIONS

This systematic review demonstrated that radiotherapy for HNC induced significant changes in the pulp response with moderate quality of evidence. Such altered responses cannot determine pulp status accurately.

Dentin-pulp complex reactions in conventional and radiation-related caries: A comparative study

Background

Radiation-related caries (RRC) is one of the most significant oral toxicities of head and neck radiotherapy (HNRT); however, the potential of radiation to directly cause harmful dentin and pulpal effects and impair response to caries progression is controversial.

Material and Methods

Therefore, the aim of this study was to characterize the reactions of the dentin-pulp complex in teeth affected by RRC. Patients and methods: Twenty-two carious teeth extracted from 22 head and neck cancer (HNC) patients were divided into control (conventional caries; n=11) and irradiated (RRC; n=11) groups and paired matched by dental homology, clinical patterns of caries progression following the Post-Radiation Dental Index (PRDI) and microscopic depth of carious invasion. Histopathological characteristics based on morphological hierarchy, cell populations of dental pulp, blood vessels, neural elements, extracellular matrix components, inflammation, patterns of carious invasion and reactionary dentin presence were evaluated by optical light microscopy and histomorphometry.

Results

Mean PRDI scores were 3.2 for the control group and 3.8 for the irradiated group. Dentin demineralization patterns were also similar between the groups and the mean depths of demineralization were 1,158.58µm and 1,056.89µm for the control and irradiated groups, respectively.

Conclusions

Pulp histopathological changes and dentin reaction patterns were similar between groups and varied according to the PRDI scores and carious lesions depth. Dentin and pulp reactions are highly preserved in RRC teeth. Key words:Cancer, radiotherapy, radiation-related caries, teeth, pulp.

Histopathological changes in dental pulp of rats following radiotherapy

BACKGROUND

Radiotherapy is one of the oral and pharyngeal cancer treatment methods that can cause damage to the tissues in the radiation area; the purpose of this study is to evaluate the effects of radiotherapy on dental pulp tissue in rats.

MATERIALS AND METHODS

In this interventional, experimental double-blind study, 30 rats were studied in three groups (n = 10 each). The first group received 12 gray (Gy), the second group received 18 Gy in one session, and the third group was not exposed to radiation (control group). The 5 μm sections of mandibular molar tooth were prepared and stained with hematoxylin and eosin. Samples were studied under optical microscope to evaluate and score inflammation, necrosis, hyalinization, and vascular congestion. The data were coded and analyzed by statistical tests of χ² and Fisher's exact tests. The significant level of P = 0.05.

RESULTS

In Group 1, necrosis in two cases, inflammation in one case, hyalinization in one case, and vascular congestion in four cases were observed. In Group 2, inflammation in four cases, hyalinization in two cases, and vascular congestion in five cases were observed. In Group 3, inflammation was observed only in one case. In comparison between the groups, no significant differences were observed in inflammation (P > 0.05), necrosis (P > 0.05), and hyalinization (P > 0.05). However, the difference was significant for vascular congestion (P < 0.05).

CONCLUSION

Radiotherapy with doses of 12 and 18 Gy had no significant effect on inflammation, necrosis, and hyalinization in all groups; however, the difference was significant for vascular congestion.

A magnetic resonance imaging study on changes in rat mandibular bone marrow and pulp tissue after high-dose irradiation

PURPOSE

This study was designed to evaluate whether magnetic resonance imaging (MRI) is appropriate for detecting early changes in the mandibular bone marrow and pulp tissue of rats after high-dose irradiation.

MATERIALS AND METHODS

The right mandibles of Sprague-Dawley rats were irradiated with 10 Gy (Group 1, n=5) and 20 Gy (Group 2, n=5). Five non-irradiated animals were used as controls. The MR images of rat mandibles were obtained before irradiation and once a week until week 4 after irradiation. From the MR images, the signal intensity (SI) of the mandibular bone marrow and pulp tissue of the incisor was interpreted. The MR images were compared with the histopathologic findings.

RESULTS

The SI of the mandibular bone marrow had decreased on T2-weighted MR images. There was little difference between Groups 1 and 2. The SI of the irradiated groups appeared to be lower than that of the control group. The histopathologic findings showed that the trabecular bone in the irradiated group had increased. The SI of the irradiated pulp tissue had decreased on T2-weighted MR images. However, the SI of the MR images in Group 2 was high in the atrophic pulp of the incisor apex at week 2 after irradiation.

CONCLUSION

These patterns seen on MRI in rat bone marrow and pulp tissue were consistent with histopathologic findings. They may be useful to assess radiogenic sclerotic changes in rat mandibular bone marrow.

Local and systemic tissue response submitted to injection of 2 and 30% polymethylmethacrylate in rats' tongue

INTRODUCTION

Adverse effects on the oral mucosa after the use of dermal fillers have been reported due to their increased use for facial aesthetics.

OBJECTIVE

This study aimed to evaluate, clinically and histologically, the local and systemic effects of two concentrations of polymethylmethacrylate (PMMA) dermal filler in rats.

MATERIAL AND METHODS

Fifty-four female rats were allocated into three treatment groups (2% PMMA, 30% PMMA and 0.9% NaCl), according to the substance injected in the tongue, and three experimental periods: 7, 60 and 90 days. The rats were clinically evaluated and then euthanised, and their tongue and right kidney removed. The histological sections were stained with haematoxylin/eosin and picrosirius.

RESULTS

Clinically, significant differences were found between test groups as to the occurrence of nodules (Kruskal-Wallis; p < 0.001). Histologically, there was greater inflammatory response in the PMMA compared with control (Kruskal-Wallis; p < 0.001). 30% PMMA had greater collagen formation (anova mixed models; p < 0.01). No migration of the material towards kidney was found.

CONCLUSION

Polymethylmethacrylate induced intense reaction in the initial period of observation (7 days), followed by gradual decrease during the study, favouring the presence of fibroplasia adjacent to the material.

Effects of gamma radiation on hard dental tissues of albino rats: investigation by light microscopy

The present work aims at studying the effect of gamma radiation on the hard dental tissues. Eighty adult male albino rats with weights of about 250 g were used. The rats were irradiated at 0.2, 0.5, 1.0, 2.0, 4.0 and 6.0 Gy whole-body gamma doses. The effects on hard dental tissue samples were investigated after 48 h in histological and ground sections using light microscopy. Areas of acid phosphatase activity were detected using tartrate-resistant acid phosphatase (TRAP) stains. Observation of histological sections revealed disturbance in predentin thickness and odontoblastic layer as the irradiation dose increased. In cementum, widened cementocytes lacunae were occasionally detected even with low irradiated doses. On the other hand, relatively homogenous enamel was detected with darkened areas in enamel surface at doses over than 0.5 Gy. TRAP-positive cells were detected on the surface of the dentin of irradiated groups as well as cementum surface. Minimal detectable changes were observed in ground sections.