Second primary cancers in pediatric head and neck cancer survivors in Denmark during 1980-2014: A nationwide study

Effect of ionizing radiation on the shear bond strength of two different adhesive systems in primary teeth. in-vitro study

BACKGROUND

Radiotherapy is a treatment modality used for head and neck cancer patients. It has a negative influence on bonding strength of adhesives. Little information is available about the effect of radiotherapy on bonding strength of adhesives in primary teeth. Therefore, this in vitro study aimed to detect the best adhesive system and ideal time to apply restorations in primary irradiated teeth regarding adhesive shear bond strength.

METHODS

Dentin samples from primary teeth were randomly assigned to four groups based on restoration application time and radiation exposure, (G1: control, G2: preradiation, G3: 24 h postradiation, and G4: 6 months postradiation) with 20 samples per group. These groups were further divided into 2 subgroups according to the adhesive system used, with 10 samples per subgroup. (1) 3M™ Single Bond Universal Adhesive (SB), (2) 3M AdperSingle Bond 2 (AS). Samples were exposed to gamma radiation from a cobalt-60 machine. One shot of 60 Gy of radiation was delivered. Then samples were subjected to a shear bond strength test. The load was applied until failure and the maximum load was recorded. Numerical data are presented as mean and standard deviation values, then distributed according to Shapiro-Wilk test or Levene's test and analyzed via two-way ANOVA. The significance level was set at p < 0.05 for all tests. Statistical analysis was performed with R statistical analysis software version 4.4.1 for Windows (Team RC, R: A language and environment for statistical computing. R foundation for statistical computing, 2023).

RESULTS

Compared with the AS subgroup, the SB subgroup presented significantly greater values (p < 0.001). For SB, there was no significant difference among the G1 and G4 groups (p > 0.001). However, there was a significant difference between G1, G2, and G3 (p < 0.001, P = 0.025, P = 0.265 ns respectively), and G3 presented the lowest values. For AS, there was no significant difference between groups G1 and G4 (p =  < 0.001). Compared with the other groups, G3 presented a significant difference (p = 0.265 ns) and the lowest results.

CONCLUSION

Restorations performed 24 h after radiation had lower bond strength than those performed six months after radiation. Regardless of the adhesive system used, SB performed better than AS in terms of the shear bond strength.

Occurrence and Prognosis of Secondary Lung Cancer in Patients with Primary Nasal Cavity and Sinus Squamous Cell Carcinoma

INTRODUCTION

There is an increasing focus on the burden of long-term survivors of secondary malignant neoplasms (SMNs) after the appearance of the primary tumor. Our goal was to describe the occurrence and prognosis of secondary lung cancer (SLC) in patients suffering from primary nasal cavity and sinus squamous cell carcinoma (NSSCC).

METHODS

Patients with NSSCC who reported to the Surveillance, Epidemiology and End Results (SEER) program between 1973 and 2017 were selected for our analysis. The Kaplan-Meier analysis was employed to predict the overall prevalence of SMNs and survival rates after the development of SMN. Standardized incidence ratios (SIRs) of SMNs have also been assessed after the development of the primary NSSCC.

RESULTS

A total of 5354 patients were diagnosed with NSSCC. The type and date of diagnosis of the first malignancy were included in the records. In total 419 patients were reported to have developed SMNs within a median duration of 36 months from the time of the primary to the secondary tumor diagnosis. The reported cumulative incidence of SMNs was 14% after 10 years from the primary tumor diagnosis and 32% after 20 years. Among the solid SMNs, secondary lung cancer was the most common malignancy, with cumulative incidences of 12.4% after 20 years. The SIR of SMNs after the primary NSSCC compared with that of the general population was 1.65 and the 5-year overall survival (OS) rate following SMNs was 30%. The SMN lung cancer exhibited a SIR of 3.21 and was associated with a short-term median survival of only 11 months.

CONCLUSIONS

NSSCC survivors are at a high risk of developing SMNs, relative to baseline individuals. Lung cancer is one of the most common SMNs, and it has a poor outcome.

Nasopharyngeal carcinoma in children and young adults-Beyond 5-year survival

Nasopharyngeal carcinoma (NPC) is a rare and locally aggressive form of childhood cancer. Treatment of NPC includes chemotherapy and radiotherapy. With current treatment protocols, survival rates for patients with nonmetastatic disease is over 80%. Data regarding very late events including long-term treatment-related morbidities and second malignancies are scarce. We present our data on 42 patients with NPC treated in Israel between 1989 and 2014, and followed until 2019. During follow up, five patients had disease recurrence, and four children developed secondary malignancy. Median time to diagnosis of secondary malignancy was 105 months. Eighty-eight percent of patients have long-term treatment-related morbidities.

Effect of different doses of radiation on morphogical, mechanical and chemical properties of primary and permanent teeth-an in vitro study

Background

Radiotherapy, applied to the head and neck region, can cause radiation side effects such as reduction of saliva and radiation caries. The aim of this study was to perform an in vitro assessment of the effects of radiation therapy on the morphological, mechanical, and chemical properties of primary and permanent teeth.

Methods

One hundred four extracted human teeth (52 impacted wisdom teeth, 52 primary molar teeth) were used. The teeth were divided into two parts in the mesiodistal direction. Of the 98 teeth, the vestibular sections were used for the vickers analysis and lingual sections were used for the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysis. The teeth in the experimental group were fixed to wax models. Each model had an equal number of teeth (n = 7). The doses were applied to the teeth for 6 weeks; 5 week days and 2Gy daily. After the radiotherapy was conducted weekly, a wax model was taken from radiation reception. Along with the elemental contents (Na, K, Mg, P, and Ca) of the teeth, enamel and dentin microhardness was evaluated, and SEM analyzes were performed on 6 teeth.

Results

Radiation caused a decrease in microhardness of enamel and dentin (p < 0.05). In the elemental analysis by ICP-OES, it was observed that there were decreases in all elements after 60Gy compared to the control group (p < 0.05). In the experimental groups, amorphous structures were encountered in SEM images.

Conclusions

Radiation has negative effects on the teeth structure and additional studies are needed in this regard. This study indicates that radiotherapy patients are at a higher risk for dental caries.