Oral Stents Research Articles

Effect of adding chrome-cobalt, titanium, and tungsten alloys to cold-cure acrylic resin oral stent for cancer patients with head and neck radiotherapy

Purpose: The main objective of this study is to develop a substance that can enhance the absorption of radiation therapy for head and neck cancer and protect the surrounding tissues of the tumor during radiotherapy. Materials and Methods: The dimensions of the specimen are 40 mm x 55 mm in length and width, with a thickness of 6 mm based on Iraqi population studies. The sample was composed of four groups, A, B, C, and D. Each group was exposed to two different types of energy, 4 MEV, and 9 MEV, by the VARIANI X2300 radiation machine. Results: The amount of radiation penetration was measured and statistically analyzed using Levene’s and two-way ANOVA tests to determine the differences and identify the best materials. The data from this study show a highly significant difference (p-value < 0.001) in radiation penetration between all groups. Conclusion: The stent made with a combination of cold-cure acrylic and tungsten alloy has the lowest radiation penetration at 4 MEV and 9 MEV energy levels, making it the best material stent for protecting healthy tissues against radiation. On the other hand, stents made solely with cold-cure acrylic offer poor radiation protection.

3D printing technology to produce intraoral stents for head and neck radiotherapy: A scoping review.

Radiotherapy remains one of the main treatments for head and neck cancer; however, it is accompanied by acute and chronic adverse effects. Use of three-dimensional (3D) oral stents to modulate radiation intensity to specific target areas have been developed to minimize these adverse effects. This study aimed to present a scoping review of studies published on 3D printing of oral stents and their clinical applicability. MEDLINE/Pubmed, Scopus, Web of Science and CENTRAL Cochrane data bases were searched, studies selected, and data collected by three independent reviewers up to December 2022. The review was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis-Extension for Scoping Reviews (PRISMA-ScR). The search resulted in 404 studies and 5 articles fulfilled the eligibility criteria and were considered for this review. Three-dimensional printed intraoral stents were produced for 56 patients with indication for radiotherapy. 3D-printed stents were well-tolerated by all tested patients and demonstrated great reproducibility of maxillomandibular relation, required less time for production and lower cost to manufacture. Two studies showed great protection of healthy tissues with 3D-printed stents during radiotherapy. Three-dimensional printing is promising for production of intraoral stents, however, more studies are needed to improve the technique and further investigate the safety and prevention of oral toxicities from radiotherapy.

The application of 3D-printed oral stents in intensity-modulated radiotherapy for oropharyngeal cancer and their dosimetric effect on organs at risk

BackgroundThis study investigates the accuracy of 3D-printed dental stents in intensity-modulated radiotherapy (IMRT) for oropharyngeal cancer (OPC) and their dosimetric effects on normal tissues.MethodsWe selected 60 patients with OPC who underwent IMRT in the Department of Oncology, Special Medical Center of Army Medical University. These patients were randomly assigned into 3D-printed oral stent, simple glass bottle, and nonstent groups (20 patients/group). The positioning error was analyzed with the onboard imaging system once a week after 5 fractions of IMRT. The conformity index (CI), homogeneity index (HI), radiation dose of organs at risk (OARs), and oral mucosal reaction were compared among the three groups.ResultsNo significant difference was observed in the conformity and uniformity of the target dose and the dose received by the spinal cord, larynx, and bilateral parotid glands among the three groups (P > 0.05). Meanwhile, the dose received by the upper cheek, hard palate, and soft palate of patients was significantly lower in the 3D-printed oral stent group than in the nonstent group (P < 0.05) but insignificantly different between the 3D-printed oral stent and simple glass bottle groups (P > 0.05). When compared with the nonstent group, the simple glass bottle group showed a markedly lower dose received by the upper cheek (P < 0.05) and an insignificantly different dose received by the hard palate and soft palate (P > 0.05). According to Common Terminology Criteria for Adverse Events v.5.0, the adverse response rate of the hard palate mucosa was lower in the 3D-printed oral stent group than in the simple glass bottle and nonstent groups (P < 0.05).ConclusionsFor OPC patients undergoing IMRT, the application of 3D-printed oral stents can significantly reduce the exposure dose of the upper cheek and hard palate and decrease the occurrence of adverse events such as oral mucositis although it cannot affect the positioning error.

Wearing individualized 3D printed oral stent to protect normal tissues in patients with nasopharyngeal carcinoma during radiotherapy.

To demonstrate a new individualized 3D printed oral stent in radiotherapy of nasopharyngeal carcinoma (NPC) patients and carry out a comparative analysis combining with clinical case. Thirty NPC patients treated in our institution from September 2021 to October 2022 were prospectively enrolled. An individualized 3D printed oral stent was designed for each patient, and one set of computed tomography (CT) slices were obtained with /without wearing the oral stent, respectively. After delineation of target volumes and organs at risk (OARs) on the two CT slices, we finished two treatment plans by using the same target objectives, critical constraints and plan setup for each patient. Finally, the dose distribution and other dosimetric parameters of target volumes and OARs between the two plans were compared. Tongue volume and tongue length outside of mouth was 10.4±2.5cm3 and 2.8±0.6cm, respectively, distance between dorsal surface of oral tongue and plate increased from 0.3±0.3cm to 2.2±0.5cm by wearing the oral stent. For the target volume, there was no significant difference. However, Dmax of tongue, tongue tip and periglottis decreased significantly from 6352.6±259.9cGy to 5994.9±478.9cGy, 3499.8±250.6cGy to 3357.7±158.0cGy and 6345.5±171.0cGy to 6133.4±263.3cGy, respectively (p=0.000); Dmean of tongue, tongue tip and periglottis decreased significantly from 3714.7±204.2cGy to 3169.7±200.9cGy, 3060.8±216.2cGy to 2509.6±196.7cGy and 3853.3±224.9cGy to 3079.3±222.0cGy, respectively (p=0.000). The individualized 3D printed oral stent can reduce the dose of oral tissues and organs, so as to reduce the oral adverse reactions and improve the compliance of patients and the quality of their life. The technique can be used in radiotherapy of NPC patients.

Design of 3D-printed universal oral stent for tongue immobilization in head and neck radiotherapy

The primary treatment for head and neck cancer is radiotherapy, which can cause complications and effects, such as the ability to speak, taste, produce saliva, and swallow. An oral stent is an immobilization tool for minimizing the dose in the tongue (or hard palate) by locking the tongue position during radiation delivery. It can improve the treatment accuracy due to less uncertainty caused by tongue position uncertainty between treatment fractions. However, commercial oral stents are not widely adopted in developing countries due to their unaffordable price. This study aimed to design the universal oral stent (UOS) to achieve high efficiency, ease to use, and low-cost fabrication based on 3D printing technology. There were five experiments to evaluate the UOS design and fabrication versus the modified cut syringe, including finite element analysis (FEA), the usability test, the micro Vickers hardness test, single beam dose analysis, and dose calculation on treatment plan simulations. The proposed UOS design and fabrication presented a high capability to apply for clinical use.

ASSOCIATION BETWEEN RADIOTHERAPY AND DENTAL CARIES IN PATIENTS WITH HEAD AND NECK CANCER: A LITERATURE REVIEW

<h3>Objectives</h3> The aim of this study was to review the literature about the presence of dental caries in patients undergoing head and neck radiotherapy. <h3>Study Design</h3> References published in the last 5 years were searched on PubMed database using the search terms "Radiation caries," "Tooth demineralization," "Dental caries," and "Radiation" combined with each other. After the reading and based on the eligibility criteria, 18 articles were included in this study. <h3>Results</h3> It was estimated that more than 80% of patients with head and neck cancer suffer from acute oral complications due to radiation, contributing to a high prevalence of tooth decay associated with radiotherapy. The absence of daily use of fluoride, frequent dental appointments, and oral hygiene and diet instructions were significantly associated with these lesions' development. Furthermore, the use of individualized radioprotective oral stents was an option to reduce xerostomia development probability and prevent dental caries as a consequence of radiotherapy. <h3>Conclusions</h3> There is a strong association between radiotherapy prescribed to patients with head and neck cancer and dental caries development. However, there are several dentistry approaches that make it possible to reduce this development risk.

Evaluation of radiodensity and dimensional stability of polymeric materials used for oral stents during external beam radiotherapy of head and neck carcinomas

PurposeIntraoral stents protect the healthy tissues from ionizing radiation during external beam radiotherapy reducing mucositis, hyposalivation and osteoradionecrosis.This study investigated the radiodensity and dimensional stability of polymeric materials for suitability in construction of intraoral stents and aimed to provide clinical guidelines. MethodsSpecimens were fabricated using 4 material types namely, resin composite (ProTemp-PRO), polymethylmethacrylate (PMMA) (Enamel Temp Plus-ETP, Palapress-PAL, TAB 2000-TAB), polycaprolactone (Orfit-ORF) and silicone (Adisil-ADI, Lab Putty-LAB, Memosil2-MEM, Optosil-OPT, President Plus-PRE, Siolaplast A-SIA).They were randomly assigned to measuretheir radiodensity inHounsfield Units(HU)(12x12x11mm3) (Nradiodensity = 66; n = 6)using a computer tomograph (CBCT,Toshiba Aquillon LB scanner)at baseline and after 6 weeks. The scanning protocol was applied with and without single energy metal artifact reduction (SEMAR) scans using a slice thickness of 1 and 5 mm.The same materials have been tested for their dimensional stability (µm3)at baseline, 1, 6, 12, 24 h, 3 and 6 weeks(14 × 4 × 2 mm3)(Ndimension = 55; n = 5 per material) using stereolithography (STL) files generated by a lab scanner (L2i, Imetric4D, Courgenay, Switzerland) and analyzed using a matchingsoftware(Geomagic ControlX 2020,3D Systems).Data were analyzed using a paired t-test (alpha = 0.05). ResultsRadiodensity values (HU) were significantly affected by the material classification (p < 0.05).Polycaprolactone(43.6) presented significantly lower HU valuesfollowed by PMMA (91.3–414.9) than those of silicone materials (292.8–874.5). In terms of dimensional stability (µm3), PMMA materials (Δ:1.53–2.68) andresin composite (Δ:2.89)were significantly more dimensionally stable compared to those of silicone materials(Δ:13.64–6.63)andpolycaprolactone (Δ:-0.76) and (p < 0.05). ConclusionFor fabricating intraoral stents, when reducedradiodensity valuesarerequiredpolycaprolactone could be recommended as it fulfils the requirements for reduced radiodensity and dimensional stability. Among all silicone materials,OPT and MEMcan be recommended based on the low HU and dimensional stability.

A Dosimetric Comparison of Oral Cavity Sparing in the Unilateral Treatment of Early Stage Tonsil Cancer: IMRT, IMPT, and Tongue-Deviating Oral Stents

IntroductionTongue-deviating oral stents (TDOS) are commonly used during unilateral neck radiation therapy to reduce unnecessary dose to nontarget oral structures. Their benefit in the setting of highly conformal treatment techniques, however, is not defined. The goal of this study was to investigate the potential benefit of TDOS use on dosimetric parameters in unilateral intensity modulated radiation therapy (IMRT) and intensity modulated proton therapy (IMPT). MethodsA total of 16 patients with T1-2 tonsil cancer treated at a single institution were selected, of which 8 were simulated/treated with a TDOS and 8 without a TDOS. All received definitive unilateral IMRT to a dose of 66 Gy in 30 fx. IMPT plans were generated for each patient for study purposes and optimized according to standard institutional practice. ResultsFor IMRT plans, the presence of a TDOS (vs without) was associated with a significantly lower oral mucosa mean dose (31.4 vs 35.3 Gy; P = .020) and V30 (42.7% vs 57.1%; P = .025). For IMPT plans, the presence of TDOS (vs without) was not associated with any improvement in oral mucosa mean dose (18.3 vs 19.9 Gy; P = .274) or V30 (25.0% vs 26.2%; P = .655). IMPT plans without TDOS compared with IMRT plans with TDOS demonstrated reduced oral mucosa mean dose (P < .001) and V30 (P < .001). ConclusionThe use of a TDOS for the unilateral treatment of well-lateralized tonsil cancers was associated with oral mucosa sparing for IMRT, but not for IMPT. Moreover, mucosa sparing was improved for IMPT plans without a TDOS compared to IMRT plans with a TDOS.

The impact of tongue-deviating and tongue-depressing oral stents on long-term radiation-associated symptoms in oropharyngeal cancer survivors

ObjectivesTo evaluate whether the use of oral stents during intensity modulated radiation therapy (IMRT) for oropharyngeal cancer (OPC) is associated with long-term patient reported symptoms. Materials and methodsData was obtained from a prospective observational study of disease-free head and neck cancer survivors. Radiation-associated patient reported symptoms were assessed using the MD Anderson Symptom Inventory Head and Neck module (MDASI-HN). Scores of ≥5 (11-point Likert scale, 0-10) were considered moderate/severe. Stratification was performed regarding IMRT volume (uni- versus bilateral neck) and stent utilization, with non-parametric analyses between groups. Results462 OPC survivors formed the cohort (54% tonsil, 46% base of tongue primaries). A tongue-deviating stent was used in 17%, tongue-depressing stent in 46%, and no stent in 37%. Median prescribed dose to the high dose clinical target volume was 66.0 Gy. Median follow-up from RT to MDASI-HN assessment was 68 months. Twenty percent had received unilateral neck RT (all had tonsil primaries), in whom a significant improvement in the proportion of patients with moderate/severe taste impairment (2% vs. 15%, p = 0.047) and lack of appetite (0% vs. 9%, p = 0.019) was associated with the use of tongue-deviating stents compared to no oral stent. In those who had received bilateral neck RT, a significant improvement in the proportion of patients with moderate/severe difficulty swallowing/chewing was associated with use of a tongue-depressing stent (21% vs. 31% without oral stent, p = 0.013). ConclusionDisease-site specific select use of oral stents during IMRT was associated with reduced long-term patient reported symptoms in OPC survivors.

A prospective parallel design study testing non-inferiority of customized oral stents made using 3D printing or manually fabricated methods.

Customized mouth-opening-tongue-depressing-stents (MOTDs) may reduce toxicity in patients with head and neck cancers (HNC) receiving radiotherapy (RT). However, making MOTDs requires substantial resources, which limits their utilization. Previously, we described a workflow for fabricating customized 3D-printed MOTDs. This study reports the results of a prospective trial testing the non-inferiority of 3D-printed to standard and commercially-available (TruGuard) MOTDs as measured by patient reported outcomes (PROs). PROs were collected at 3 time points: (t1) simulation, (t2) prior to RT, (t3) between fractions 15-25 of RT. Study participants received a 3D-printed MOTDs (t1, t2, t3), a wax-pattern (t1), an acrylic-MOTDs (t2, t3) and an optional TruGuard (t1, t2, t3). Patients inserted the stents for 5-10min and completed a PRO-questionnaire covering ease-of-insertion and removal, gagging, jaw-pain, roughness and stability. Inter-incisal opening and tongue-displacement were recorded. With 39 patients, we estimated 90% power to detect a non-inferiority margin of 2 at a significance level of 0.025. Matched pairs and t-test were used for statistics. 41 patients were evaluable. The 3D-printed MOTDs achieved a significantly better overall PRO score compared to the wax-stent (p=0.0007) and standard-stent (p=0.0002), but was not significantly different from the TruGuard (p=0.41). There was no difference between 3D-printed and standard MOTDs in terms of inter-incisal opening (p=0.4) and position reproducibility (p=0.98). The average 3D-printed MOTDs turn-around time was 8 vs 48h for the standard-stent. 3D-printed stents demonstrated non-inferior PROs compared to TruGuard and standard-stents. Our 3D-printing process may expand utilization of MOTDs.

The validity of oral prosthetic stents for maxillofacial cancer during radiation therapy: Case report

The validity of oral prosthetic stents for maxillofacial cancer during radiation therapy: Case report

Prospective Observational Registry Cohort Evaluation of Oral Stents as Method to Reduce Long-term Radiation-induced Toxicity in Oropharyngeal Cancer Patients

Prospective Observational Registry Cohort Evaluation of Oral Stents as Method to Reduce Long-term Radiation-induced Toxicity in Oropharyngeal Cancer Patients

Creating customized oral stents for head and neck radiotherapy using 3D scanning and printing

BackgroundTo evaluate and establish a digital workflow for the custom designing and 3D printing of mouth opening tongue-depressing (MOTD) stents for patients receiving radiotherapy for head and neck cancer.MethodsWe retrospectively identified 3 patients who received radiation therapy (RT) for primary head and neck cancers with MOTD stents. We compared two methods for obtaining the digital impressions of patients’ teeth. The first method involved segmentation from computed tomography (CT) scans, as previously established by our group, and the second method used 3D scanning of the patients’ articulated stone models that were made during the conventional stent fabrication process. Three independent observers repeated the process to obtain digital impressions which provided data to design customized MOTD stents. For each method, we evaluated the time efficiency, dice similarity coefficient (DSC) for reproducibility, and the 3D printed stents’ accuracy. For the 3D scanning method, we evaluated the registration process using manual and automatic approaches.ResultsFor all patients, the 3D scanning method demonstrated a significant advantage over the CT scanning method in terms of time efficiency with over 60% reduction in time consumed (p < 0.0001) and reproducibility with significantly higher DSC (p < 0.001). The printed stents were tested over the articulated dental stone models, and the trueness of fit and accuracy of dental anatomy was found to be significantly better for MOTD stents made using the 3D scanning method. The automated registration showed higher accuracy with errors < 0.001 mm compared to manual registration.ConclusionsWe developed an efficient workflow for custom designing and 3D-printing MOTD radiation stents. This workflow represents a considerable improvement over the CT-derived segmentation method. The application of this rapid and efficient digital workflow into radiation oncology practices can expand the use of these toxicity sparing devices to practices that do not currently have the support to make them.

P38 - A Prospective Trial Evaluating Patient Reported Outcomes of Customized Oral Stents for Head and Neck (HN) Radiotherapy (RT) Using 3D Printing and Traditional Methods

P38 - A Prospective Trial Evaluating Patient Reported Outcomes of Customized Oral Stents for Head and Neck (HN) Radiotherapy (RT) Using 3D Printing and Traditional Methods

P39 - A Dosimetric Comparison of Oral Cavity Sparing in the Unilateral Treatment of Early Stage Tonsil Cancer: IMRT, IMPT, and Tongue Deviating Oral Stents

P39 - A Dosimetric Comparison of Oral Cavity Sparing in the Unilateral Treatment of Early Stage Tonsil Cancer: IMRT, IMPT, and Tongue Deviating Oral Stents

Construction and clinical evaluation of a new customized bite block used in radiotherapy of head and neck cancer

PurposeIn the present study we constructed a new customized bite block and evaluated its effect on dosimetric and clinical features in radiotherapy. Materials and methodsThe key point of this method is using the oral stent and silicon rubber through a procedure of making fine intraoral impressions. For type I customized bite block, only the upper and lower alveoli of the oral stent are coated with silicone rubber and impressions of the teeth can be obtained. For type II customized bite block, all parts of the oral stent are coated with silicone rubber to make sure impressions of the teeth, tongue and other intraoral tissues can be obtained. Sixty patients undergoing radiotherapy of nasal cavity, paranasal sinuses and oromaxillofacial area were evaluated. For each patient, intensity-modulated radiotherapy plans created with and without customized bite block were compared and data were collected on radiation-induced complications. ResultsThe total fabricating time was approximately 20minutes, and the cost was approximately 10 US dollars. Type I customized bite block is applicable to cancer of sinuses and nasal cavity. Type II customized bite block is applicable to cancer of the oral cavity, salivary glands, especially tongue cancer. The use of the customized bite block showed promising results in decreasing the radiation dose to organs at risk during intensity-modulated radiotherapy. No patients had oral mucositis (grade 3 or above), taste dysfunction, or xerostomia during and post radiotherapy. ConclusionA customized bite block is easy-made and worthy of clinical use.

In vivo dosimetry of intraoral stent using TLD during external photon beam radiotherapy of oral cavity

Introduction: Individual oral stent is a mouth-opening device that used in head and neck cancer radiotherapy with the intention of decreasing radiation dose to health tissues. The aim of this study was to check the dose delivered to both the hard palate and tongue when patient uses the stent during radiotherapy of tongue carcinoma. Methods and materials: The intraoral stents were made for 10 patients and TLD-100 dosimeters were placed at superior and inferior parts of stent at the level of hard palate and tongue, respectively. Then patients treated with 3DCRT technique using 6MV photons, the data from the TLDs and treatment planning system calculations were analyzed. Results: The results showed that the mean (±standard deviation) relative difference between measured and calculated doses for tongue and hard palate was -4.41± 6.34, 0.57± 9.6 respectively. Conclusion: This study demonstrated the value of thermoluminescent dosimetry as a treatment verification method and its usefulness departmental quality assurance program.

Use of 3-D Printed Custom Oral Stents to Improve Positioning and Reproducibility for Patients Treated for Head and Neck Cancer

Use of 3-D Printed Custom Oral Stents to Improve Positioning and Reproducibility for Patients Treated for Head and Neck Cancer

Design of Individualized Oral Radiotherapy Stent Based on 3D Printing Technique

This paper introduces the individual design of oral radiotherapy stent based on 3D printing technology, and expounds its design principle. The modeling of the device is based on CT images and Mimics software, which builds a set of 3D printing oral stent technology. The instrument has more advantage in high precision, fast modeling, individualized production and digital storage. The results show that the construction of 3D printed dental stent is feasible, which provides a new idea and method for the production of oral stents.

A novel method to prevent biting through nasolabial flap: Modified oral screen

ObjectiveOral submucous fibrosis (OSMF) is a chronic, progressive precancerous condition of oral mucosa, predominantly seen in the Indian subcontinent. This technical note describes the use of oral screen prosthesis used as an adjunct to surgery to prevent relapse following surgical correction. MethodsThe modified oral screen appliance was inserted in the patient’s labial and buccal vestibule as oral screen. The appliance was intended to be used as an oral stent along with mouth exercises to counteract relapse of the corrected mouth opening. ResultsThe possibility of flap shrinkage and interference with occlusion results in surgical failure of the treatment of OSMF. Securing the flap in position using oral screen prosthesis has been tried as an adjunct to treat such cases. ConclusionsThis modified approach can be performed in routine clinical practice, making the rehabilitation of such a case possible with relative ease.