The wolf in sheep's clothing: Microtomographic aspects of clinically incipient radiation-related caries

Conformational and constitutional analysis of dental caries following radiotherapy for head and neck cancer

Background

This study aimed to investigate the morphology and chemical composition of dental caries related to ionizing radiation (DCIR), an aggressive and progressive disease that affects dental hard tissues.

Materials and methods

Eight human teeth with DCIR were paired with sixteen control teeth (8 teeth with conventional caries and 8 without caries) and included in this study. An analysis of the morphology of the lesions was performed using the following techniques: periapical radiography, cone beam computed tomography, computed microtomography, and scanning electron microscopy. The chemical composition was assessed using X-ray dispersive spectroscopy.

Results

There was more demineralization in DCIR lesions when compared to conventional dental caries, even though there was no cavitation in the cervical region of the teeth. The superficial roughness and topography of DCIR lesions were similar to those of healthy teeth. On the other hand, lesions of conventional dental caries showed greater surface and topographic irregularity when compared to DCIR and healthy teeth (p = 0.001). Calcium (Ca) and phosphorus (P) levels were lower in DCIR lesions when compared to controls. However, higher levels of carbon (C) have been observed in DCIR lesions. There was a greater loss of the mineral matrix in DCIR followed by conventional caries. The reduction in the mineral matrix (Ca and P) was compatible with the imaging patterns observed in teeth with DCIR and conventional caries.

Conclusion

Despite their rapid evolution, DCIR presents an irregular, apparently intact surface with significant changes in the amount of Ca, P, and C.

Morphological patterns of circumpulpal dentin affected by radiation-related caries

BACKGROUND

The aim of this work was to evaluate the microscopic characteristics through polarized light microscopy, scanning electron microscopy and the mineral content of circumpulpal dentin of irradiated (IT) and non-irradiated teeth (NIT), with deep caries that reached the root canal.

MATERIAL AND METHODS

A total of 25 IT were analyzed macroscopically, and radiographed. 5 NIT were used as controls. Two 100-μm-thick sections, per specimen, were evaluated in a polarized light microscopy and a scanning electron microscope. Demographics and clinical data were collected.

RESULTS

The results did not demonstrate distinct morphology of the IT compared with NIT. Mineral content values by weight percentage of Ca and P were also similar, corresponding to 66.65% and 33.21% in the IT and 66.60% and 33.29% in the NIT. The Ca/P ratio did not show statistical differences between groups being respectively 2.74 and 2.72, in the IT and NIT (p> 0.05).

CONCLUSIONS

Radiotherapy does not change morphology and mineral content of circumpulpal dentin in IT. Key words:Root canal, radiation-related caries, polarization microscopy, scanning electron microscopy, radiotherapy, oral neoplasms, dentin.

Impact of Clustering Oral Symptoms in the Pathogenesis of Radiation Caries: A Systematic Review

Radiation-related caries (RRC) is a disease with a high potential for destruction of the dentition, which impairs quality of life in head-and-neck (HN) cancer (HNC) patients who undergo radiotherapy. In light of the recently described “clustering of oral symptoms theory,” the present systematic review (PROSPERO CRD42019132709) aims to assess HN and gastrointestinal (GI) symptom clusters among HNC patients and discusses how these indirect effects of cancer therapy play a pivotal role in the pathophysiology of RRC. The search was performed at PubMed, Scopus, and Embase and resulted in 11 studies that met the inclusion criteria. Data extraction was performed with respect to the presence of HN/GI symptom clusters among HNC patients. The methodological data of the studies included were assessed using the MAStARI and GRADE instruments. The most prevalent reported HN symptoms were dysphagia, xerostomia, and pain. Taste alterations and fatigue were also commonly reported by the patients. Loss of appetite and weight loss were regularly reported in the studies, as well as nausea and vomiting. The results of the present study suggest that HNC treatment generates clusters of oral symptoms, leading to dietary changes, impaired oral hygiene, enamel fragility, and a highly cariogenic oral environment, which may impact the risk for RRC. A better understanding of oral symptom clustering could be of considerable clinical significance for the oral health and quality of life of HNC patients. Therefore, contemporary protocols of RRC prevention must take this broader treatment scenario of symptom clusters such as oral side effects into account.

The impact of head and neck radiotherapy on the dentine-enamel junction: a systematic review

Background

Radiotherapy is widely used in contemporary head and neck cancer treatment protocols. The ability of head and neck radiotherapy (HNRT) to cause direct radiogenic destruction to the teeth is one of the most controversial topics in the field of oral oncology. Therefore, this systematic review aimed to investigate ionising radiation as an independent factor for physical and chemical changes on the dentine-enamel junction (DEJ), a pivotal dental topography for the onset and progression of radiation-related caries (RRC) and enamel delamination.

Material and Methods

Systematic searches were conducted on three databases: Scopus, MEDLINE (Via PubMed) and Embase (Elsevier). Laboratory studies evaluating the effects of simulated or in vivo HNRT on the DEJ were included. The GRADE tool adapted for in vitro studies was used to assess the methodological quality.

Results

Of the 154 initially selected studies, eight met the inclusion criteria, from which five studies were graded as high quality of evidence, two studies were graded as moderate quality and one as low quality. Two studies did not demonstrate DEJ alterations following HNRT while the other six articles described several organic and inorganic changes in the DEJ of irradiated teeth samples. These radiogenic events were mostly detected through micro and nanoindentation, Raman micro-spectroscopy, confocal microscopy, Western blotting and optical coherence tomography.

Conclusions

HNRT may have a negative impact on the physical and chemical aspects of the DEJ, predisposing cancer patients to RRC and enamel delamination.

Key words:Cancer, radiotherapy, radiation-related caries, dentin-enamel junction, systematic review.

Effect of radiotherapy on the chemical composition of root dentin

BACKGROUND

The radiotherapy can directly affect the bond strength of the adhesive materials, interfering in the prognosis of restorative treatments, which may be caused by chemical changes in dentin structure.

METHODS

Twenty inferior homologues premolars were distributed in 2 groups (in vitro study) (n = 10): nonirradiated and irradiated. The specimens were submitted to the analysis of phosphate (ν₁ PO₄ ^3- ;ν₂ PO₄ ^3- ;ν₄ PO₄ ^3- ), carbonate (ν₃ CO₃ ^2- ), amide I, CH₂ , amide III, and amide I/III ratio by confocal Raman spectroscopy. Data were submitted to statistical analysis (T test, P < .05).

RESULTS

In intracanal dentin, the irradiated group had lower ν₄ PO₄ ^3- values (1.23 ± 0.06) compared to nonirradiated group (1.40 ± 0.18) (P < .05), with no difference for ν₁ PO₄ ^3- and ν₂ PO₄ ³ peaks (P > .05). The irradiated (1.56 ± 0.06) had lower carbonate, amide III (1.05 ± 0.19), and amide I/III ratio values (0.19 ± 0.06) compared to nonirradiated group (1.42 ± 0.10, 1.28 ± 0.24, and 0.31 ± 0.10, respectively) (P < .05). For medium dentin irradiated group (1.30 ± 0.12) had lower phosphate values compared to nonirradiated group (1.48 ± 0.22) (P < .05). In cementum, there was no statistical difference between the groups.

CONCLUSION

The radiotherapy was able to cause changes in ν₄ PO₄ ^3- , carbonate, and amide III peaks of root dentin.