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Objective: The purpose of this research was to compare two treatment techniques for oropharyngeal cancers: conventional linac-based static intensity-modulated radiotherapy (sIMRT) and helical tomotherapy (HT). The study examined several parameters, including target coverage, organs at risk, integral dose, and beam on time. Additionally, the study evaluated the doses to the parotid, temporomandibular joint, and pharyngeal constrictor muscles, which are important for swallowing., Method: The present study retrospectively analyzed the data of 13 patients with oropharyngeal cancer who underwent radiotherapy between 2019 and 2021. The treatment plans for each patient were regenerated using both sIMRT and HT treatment planning systems with the sequential boost method. The techniques were evaluated and compared based on dose-volume histogram, homogeneity index, and conformity index parameters. The target coverage and organs at risk were statistically compared for two techniques. Additionally, the doses received by the healthy tissue volume were obtained for integral dose evaluation. The beam on time for each technique was assessed., Results: When considering planning target volume evaluation, there was no difference in D means between the two techniques and sIMRT demonstrated higher D 2% values compared to the HT. The HT technique had better results for all organs at risk, such as the parotid, temporomandibular joint, and pharyngeal constrictor muscle. As for integral dose, it has been shown that the sIMRT technique provides better protection compared to HT. In addition, the beam on time was also longer with the HT technique., Conclusion: Both techniques may provide optimal target coverage for patients with oropharyngeal cancer. HT conferred notable advantages, especially with regard to critical structures implicated in swallowing, such as the parotid, temporomandibular joint, and pharyngeal constrictor muscle, in comparison to sIMRT., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The aim of the present study was to evaluate the effects of photobiomodulation (PBM) with the simultaneous use of red and infrared LEDs on pain and mandibular range of motion in individuals with temporomandibular disorder (TMD). Eighteen participants were randomly allocated to an LED group or control group. The device had 18 red LEDs (660 nm) and 18 infrared LEDs (850 nm), with a total power irradiated of 126 mW and 75.6 J per point. The device was placed in the regions of the temporomandibular joint (TMJ) and masticatory muscles once per day three times per week for 2 weeks. Pain intensity was measured using the visual analog scale (VAS). Mandibular range of motion was determined using digital calipers and considering different conditions (unassisted opening without pain, maximum opening with and without assistance, right and left lateral movements, and protrusion). Evaluations were performed before treatment, immediately after the first LED irradiation session and at the end of six sessions. A significant reduction in pain intensity was found in the LED group at the end of treatment compared to the control group (p < 0.001) as well as in the comparison between the pretreatment and end of treatment evaluations (p < 0.001). Regarding mandibular movements, no statistically significant differences between the LED group and control group were found at the end of treatment for any of the conditions analyzed or in the comparison between the beginning and end of treatment with LED. Photobiomodulation using a cluster with red and infrared LEDs induced a reduction in pain in individuals with temporomandibular disorder but did not alter mandibular range of motion in these individuals. Trial registration number: NCT03696706; retrospectively registered (ClinicalTrials.gov)., (© 2022. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

Photobiomodulation (PBM) has been applied as a non-invasive technique for treating temporomandibular joint symptoms, especially on painful condition's relief, however the anti-inflammatory mechanism underlying the effect of PBM remains uncertain. This study aims to evaluate the mechanisms of action of PBM (808 nm) in a carrageenan-induced inflammation on temporomandibular joint (TMJ) of rats. In this study male Wistar rats were pre-treated with irradiation of a low-power diode laser for 15 s on TMJ (infra-red 808 nm, 100 mW, 50 J/cm 2 and 1.5 J) 15 min prior an injection in the temporomandibular joint of carrageenan (100 μg/TMJ). 1 h after the TMJ treatments, the rats were terminally anesthetized for joint cavity wash and periarticular tissues collect. Samples analysis demonstrated that PBM inhibit leukocytes chemotaxis in the TMJ and significantly reduces amounts of TNF-α, IL-1β and CINC-1. In addition, Western blotting analysis demonstrated that PBM significantly decreased the protein levels of P2X3 and P2X7 receptors in the periarticular tissues. On the other hand, PBM was able to increase protein level of IL-10 (anti-inflammatory cytokine). In summary, it is possible to suggest that PBM inhibit inflammatory chemotaxis, modulation the balance of the pro- and anti-inflammatory characteristics of inflammatory cells., (Copyright © 2021 Elsevier B.V. All rights reserved.)

This study aimed to investigate the anti-inflammatory effects of different dosage of low-level laser therapy (LLLT) in an experimental model of temporomandibular joint (TMJ) arthritis. One hundred male Wistar rats were used and divided into the following groups: CG, control group; AG, animals group with left TMJ arthritis induced by intra-articular injection of Complete Freund's adjuvant - CFA; LG5, LG10 and LG20 - animals with arthritis and treated with LLLT at doses 5, 10, and 20 J/cm 2 , respectively. Morphological analysis was performed by TMJ histological sections stained with hematoxylin-eosin (HE), picrosirius (PSR), and toluidine blue (TB), as well as histomorphometric evaluation of cartilage, articular disc, and masticatory muscles. The amount of feed consumed within 3 weeks was evaluated, and biochemical analysis of TMJ tissues included measurement of sulfated glycosaminoglycans (GAGs), matrix metalloproteinases (MMPs) 2 and 9 zymography, and ELISA for cytokines IL-6, TNF-α, and IL-1β. Only the 20 J/cm 2 dose promoted higher feed intake compared to AG. On the other hand, all LLLT doses promoted better organization of articular disc collagen fibers, greater number of proteoglycans in articular cartilage, increased area and diameter of left lateral pterygoid fibers, reduced latent and active MMP 9 and 2 activity, and lower IL-1β concentration compared to AG. Considering the study limitations, it was observed that LLLT treatments were effective in protecting and tissue cleansing joint structures, accelerating tissue repair, especially at lower doses.

This study analyzed the effects of photobiomodulation (PBM) with low-level laser therapy on nociceptive behavior and neuronal activity in the trigeminal nucleus after experimental unilateral temporomandibular joint (TMJ) disc injury. The animals were divided into 4 groups (n = 10 each): group 1, surgical injury of the articular disc and PBM; group 2, sham-operated subjected to PBM; group 3, surgical injury of the articular disc; and group 4, control (Naïve). Ten sessions of PBM were performed using GaAs laser with a wavelength of 904 nm, power of 75 W pico, average power of 0.043 W, area of the beam of 0.13 cm 2 , duration of the pulses of 60 nseg (in the frequency of 9500 Hz), energy density of 5.95 J/cm 2 , energy per point of 0.7 J, and power density of 333.8 mW/cm 2 , and the irradiation was done for 18 s per point. Neuropathic symptoms were evaluated using the von Frey test. Trigeminal ganglion samples underwent immunoblotting to examine the expression of substance P, vanilloid transient potential receptor of subtype-1 (TRPV-1), and peptide related to the calcitonin gene (CGRP). There was a total decrease in pain sensitivity after the second session of PBM in operated animals, and this decrease remains until the last session. There was a significant decrease in the expression of SP, TRPV-1, and CGRP after PBM. Photobiomodulation therapy was effective in reducing nociceptive behavior and trigeminal nucleus neuronal activity after TMJ disc injury.

Background/aim: The aim of this study was to develop a normal tissue complication probability (NTCP) model for trismus in head and neck cancer (HNC) patients treated with radiotherapy (RT)., Patients and Methods: Prospective measurements of maximum inter-incisal opening (MIO) were performed at baseline and 6 months after definitive RT in 132 HNC patients. The primary endpoint of this study was defined when a patient fulfilled both of the following criteria: 1) MIO at 6 months after RT ≤35 mm and 2) MIO at 6 months after RT ≤80% of baseline MIO. Eleven clinical factors and a wide range of dosimetric factors (mean dose, maximum dose, V5, V10, V20, and V40) in twelve organs at risk (OARs) were chosen as candidate prognostic variables., Results: Thirty out of 132 patients (23%) developed the primary endpoint. Multivariate logistic regression analysis revealed that the mean dose to the contralateral mandible joint (p=0.001) and baseline MIO (p=0.027) were independent prognostic factors., Conclusion: A multivariable NTCP model for trismus in HNC patients treated with RT was established including the mean dose to contralateral mandible joint and baseline MIO., (Copyright© 2019, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Objectives: Platelet-rich plasma (PRP) was administered into the temporomandibular joint (TMJ) space, which had been exposed to radiotherapy (RT), in an attempt to prevent and/or treat the late-term complications associated with RT when used for the treatment of head and neck cancers (nasopharyngeal cancer in particular) on the musculoskeletal system., Methods: A total of 13 adult male New Zealand ( Oryctolagus cuniculus) rabbits were used in the study. The animals were classified into 3 groups: 6 in the RT group, 6 in the RT+PRP group, and 1 in the control group (exposed to neither). The TMJ space of each rabbit was exposed to 2240 cGy external RT in total, and PRP was administered into the TMJ space 1 month later. The joints were surgically removed 1 month later and examined histopathologically., Results: In the group given RT+PRP, the level of inflammation, amount of muscle fibrosis, vascular wall fibrosis, synovial membrane and condyle cartilage thickness, temporal extrabone fibrous cell layer count, and intramuscular changes were similar to those recorded in the control group, although the positive effects of PRP were not found to be statistically significant., Conclusions: The findings of the present study demonstrate that injections of PRP may increase joint inflammation and therefore enhance blood supply, resulting in the onset of regeneration. These favorable effects of PRP may be helpful in the fight against late-term musculoskeletal complications of RT and may minimize such side effects as sore jaw, malnutrition, and weight loss.

Changes involving temporomandibular joint, masticatory musculature, and associated structures characterize temporomandibular dysfunction (TMD). The analgesic and anti-inflammatory effect produced by photobiomodulation has contributed to pain relief and functional improvement. However, the parameters to be used have not yet been well established. The aim of this study is to compare the efficacy of three different photobiomodulation dosimetries in the treatment of patients with TMD. A randomized, double-blind, placebo-controlled clinical trial with 44 subjects divided into the groups 8 J/cm 2 (n = 11), 60 J/cm 2 (n = 11), 105 J/cm 2 (n = 11), and control (n = 11). Pain, symptom severity, and joint mobility were evaluated before and after a ten-session protocol of photobiomodulation with AlGaAs laser (830 nm), at a power density of 30 mW/cm 2 . The mouth opening increased in the 8-J/cm 2 group from 10.49 ± 4.68 to 15.40 ± 6.43 degrees, and in the right protrusion from 9.80 ± 4.2 to 12.56 ± 5.40 degrees after the intervention protocol (p < 0.05). All groups significantly decreased pain (p < 0.05). 830-nm laser photobiomodulation was effective in reducing TMD pain and symptoms at all doses tested. Only the doses of 8 J/cm 2 were effective regarding maximal opening and protrusion of the mandible.

Purpose: To explore the potential molecular mechanism of low-intensity pulsed ultrasound (LIPUS) in the treatment of temporomandibular joint osteoarthritis (TMJ-OA), and identify the target genes for therapy of TMJ-OA., Methods: Rat TMJ-OA was induced by unilateral occlusal trauma (UOT). At 8 weeks, the experimental group rats were treated by LIPUS for 4 weeks (5 days every week). The cartilage was examined by histological techniques. Gene expression profile in control, placebo and LIPUS-treated group were measured by RNA sequencing (RNA-Seq). Gene oncology (GO) and kyoto encyclopedia of genes and genomes (KEGG) annotated were performed and ten differentially expressed genes (DEGs) were further validated in another individual by quantitative real-time polymerase chain reaction (qRT-PCR). Per-2, a circadian rhythm gene, was further confirmed by western blot., Results: TMJ-OA model was successfully established in rats through UOT. LIPUS played a positive role in attenuating the retrogression of cartilage. The cartilage lesion was determined by HE and Safranin-O staining. A significant and bran-new gene profile of 58 mRNAs was obtained from the RNA-Seq (LIPUS-treated/placebo) and generated approximately 30GB data. Annotation, functional classification and pathway of the data were analyzed based on GO and KEGG database and ten candidate DEGs were identified. Some of these genes were proved to be related to OA, such as matrix-degrading enzyme (ADAMTS-8), complement (C1qa, C3, C5aR1). Some were reported for the first time in TMJ-OA, such as circadian gene (Per-2, Dbp, Npas2 and Arntl). According to the results of qRT-PCR validation, the sequencing data was with a high degree of credibility. The circadian gene Per-2 was up-regulated by LIPUS in TMJ-OA on the mRNA and protein level., Conclusion: This study reveals the potential therapeutic genes related to TMJ-OA. Especially the circadian Per-2 gene was detected up-regulated by the treatment of LIPUS. It provides us a precious, new target OA-related gene and further investigation of gene-function will provide us new insights in understanding the potential mechanical underling TMJ-OA., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Aims: This feasibility study aimed to identify relationships between radiation doses to the masticatory apparatus as a combined block or as individual subunits with changes in trismus following radiotherapy., Material and Methods: Twenty patients from a single center were recruited prospectively as part of a randomized trial comparing proactive exercises in the management of trismus. Patients with stage III/IV oral cavity or oropharyngeal squamous cell cancers received intensity-modulated radiotherapy with concurrent systemic therapy. All patients had trismus prior to radiotherapy. Maximal inter-incisor distance (MID) was measured pre- and 6 months from the start of radiotherapy. Bilateral muscles of mastication: medial and lateral pterygoids (MP and LP), masseters (M), temporalis (T), temporomandibular joint (TMJ) were contoured on CT images. The block comprised all muscles excluding the TMJ below the orbital floor. Mean dose, equivalent uniform dose (EUD) and V35-V60 Gy were compared with change in MID., Results: In six patients, the MID deteriorated at 6 months from the start of radiotherapy compared with 14 whose MID improved. No significant association was observed between age, gender, smoking, alcohol status, exercise compliance, cisplatin, tumor site, stage, V35-V60 Gy or EUD with change in MID. A clinical outlier was excluded. Without the outlier (n = 19), a significant association was seen between mean dose and change in MID at 6 months for the ipsilateral block (p = .01), LP (p = .04) and M (p < .01). All patients where trismus deteriorated at 6 months received mean doses >40 Gy to the block., Conclusion: Higher mean radiation doses to the ipsilateral block, LP and M were significantly associated with deterioration in trismus. Limiting dose to these structures to ≤40 Gy for tumors not invading the masticatory muscles may improve treatment-related sequelae. The ipsilateral block, LP and M should be studied further as possible alternative avoidance structures in radiotherapy treatment planning.

Background: Temporomandibular disorder (TMD) is described as a subgroup of orofacial pain with a set of signs and symptoms that involve the temporomandibular joint, masticatory muscles, ears, and neck. TMD can occur unilaterally or bilaterally and approximately 70% of the population is affected with at least one sign. The disorder progresses with orofacial pain, muscle pain involving the masticatory and cervical muscles, joint noises (clicks and pops), joint block, mandibular dysfunction, and headache. The etiology can be abnormal occlusion and/or posture, trauma involving local tissues, repetitive microtrauma, parafunctional habits, and an increase in emotional stress. Studies have demonstrated that phototherapy is an efficient option for the treatment of TMD, leading to improvements in pain and orofacial function., Methods: The aim of the proposed study is to compare the effects of two sources of photobiomodulation in individuals with TMD. A randomized, controlled, double-blind, clinical trial is proposed, which will involve 80 individuals aged 18-65 years allocated to either a laser group or light-emitting diode (LED) group submitted to 12 sessions of phototherapy. The Research Diagnostic Criteria for TMDs will be used to evaluate all participants. Pain will be measured using the visual analog scale and maximum vertical mandibular movement will be determined with the aid of digital calipers., Discussion: This study compares the effects of two modalities of laser therapy on the pain and orofacial function of patients with TMD dysfunction. Photobiomodulation and LED therapy are treatment options for reducing the inflammatory process and pain as well as inducing the regeneration of the target tissue., Trial Registration: ClinicalTrials.gov, NCT03257748 . Registered on 8 August 2017.

Objective: Radiation-induced trismus, which is resulted from damage of the temporomandibular joint (TMJ), is one of the common late complications in nasopharyngeal carcinoma (NPC) patients after radical radiotherapy. This study investigated the radiation induced TMJ changes using ultrasonography in post-radiotherapy (post-RT) NPC patients., Methods: 114 NPC patients, who had completed radiotherapy for more than 4 years, were assessed with the maximum incisal distance (MID) and ultrasonography examination of TMJ from which the maximum disc thickness of the joint disc, the condyle irregularity (CI), joint vascularity (JV) and relative muscle echogenicity were assessed. The same assessments were conducted on 100 age-matched normal subjects. The results were compared among the patients with and without trismus, and the control group. The mean doses to the TMJ were estimated using the treatment planning system and their correlation with the magnitude of MID was also investigated by the Pearson correlation test., Results: 39 out of the 114 patients (34.2%) presented with trismus. The average mean TMJ for all patients was 41.4 Gy, in which patients with trismus was significantly higher than patients without trismus (p = 0.017). The mean MID of patient group was significantly lower than control group (p < 0.001). The mean maximum disc thickness of the patient group was significantly smaller than the control group, whereas the mean CI and JV were significantly higher in patient group. For relative muscle echogenicity, a higher percentage of the control group showed hyperechoic pterygoid muscle than the patient group. The mean total dose to the TMJs for the patient group was 41.4 Gy and there was a mild negative correlation between the mean TMJ dose and the MID (r = -350)., Conclusion: The TMJ in post-RT NPC patients showed reduction of disc thickness, increase of CI and JV. Patients with trismus demonstrated thinner disc thickness and higher JV than those without trismus. Advances in knowledge: Our study was the first cross-sectional comparative study involving over 100 patients and normal subjects that used ultrasound to assess the radiation-induced morphological changes of TMJ. Post-RT TMJ changes characterized by the reduction of disc thickness, increase of CI and JV were detected in the NPC patients. The parameters used in this study were able to detect the morphological differences between the patient group and control group, and therefore can be effectively used to monitor the TMJ condition of post-RT NPC patients.

Intensity-modulated radiation therapy (IMRT) is the gold standard for head and neck irradiation. It allows better protection to the organs at risk such as salivary glands and mandible, and can reduce the frequency of xerostomia, trismus and osteoradionecrosis. At the time of treatment planning, the mean dose to a single parotid gland should be kept below 26Gy, the mean dose to a single submandibular gland below 39Gy, the mean dose to the mandible below 60 to 65Gy and the D2% to a single temporomandibular joint below 65Gy. These dose constraints could be further improved with data extracted from cohorts of patients receiving IMRT exclusively. The dose administered to the target volumes should not be lessened to spare the salivary glands or mandible., (Copyright © 2016 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Temporomandibular disorders (TMDs) are mostly inflammatory conditions widespread in the population. Previous studies have shown positive effects of either laser or light-emitting diode (LED) phototherapies on treating TMDs, but their action and mechanism in the inflammatory infiltrate of the temporomandibular joint are still poorly understood. The aim of this study was to assess, through histological analysis, the effectiveness of using laser light (λ 780 nm, 70 mW, continous wave (CW), 10 J) and LED (λ 850 ± 10 nm, 100 mW, CW, 10 J) on the inflammation of the temporomandibular joint of rats induced by carrageenan. Forty-five animals were divided into three groups with five animals each according to the experimental times of 2, 3, and 7 days: inflammation, inflammation+laser phototherapy, and inflammation+LED phototherapy. The first irradiation was performed 24 h after induction with an interval of 48 h between sessions. After animal death, specimens were processed and stained with hematoxylin-eosin (HE) and picrosirius. Then, the samples were examined histologically. Data were statistically analyzed. The inflammation group showed mild to moderate chronic inflammatory infiltrate between bone trabecules of the condyle. Over the time course of the study in the laser group, the region of the condyle presented mild chronic inflammation and intense vascularization. In the LED group, the condyle showed aspects of normality and absence of inflammation in some specimens. In all the time points, the laser-irradiated groups showed greater amount of collagen deposition in the condyle (p = 0.04) and in the disc (p = 0.03) when compared to the inflammation and LED groups, respectively. Laser- and LED-treated groups demonstrate a smaller number of layers of the synovial membrane when compared to the non-irradiated groups. It was concluded that, in general, laser and LED phototherapies resulted in a reduction of inflammatory infiltrate in the temporomandibular joint of rat.

The aim of this study was to investigate the analgesic and anti-inflammatory activity of low-level laser therapy (LLLT) on the nociceptive behavioral as well as histomorphological aspects induced by injection of formalin and carrageenan into the rat temporomandibular joint. The 2.5% formalin injection (FRG group) induced behavioral responses characterized by rubbing the orofacial region and flinching the head quickly, which were quantified for 45 min. The pretreatment with systemic administration of diclofenac sodium-DFN group (10 mg/kg i.p.) as well as the irradiation with LLLT infrared (LST group, 780 nm, 70 mW, 30 s, 2.1 J, 52.5 J/cm(2), GaAlAs) significantly reduced the formalin-induced nociceptive responses. The 1% carrageenan injection (CRG group) induced inflammatory responses over the time-course of the study (24 h, and 3 and 7 days) characterized by the presence of intense inflammatory infiltrate rich in neutrophils, scanty areas of liquefactive necrosis and intense interstitial edema, extensive hemorrhagic areas, and enlargement of the joint space on the region. The DFN and LST groups showed an intensity of inflammatory response that was significantly lower than in CRG group over the time-course of the study, especially in the LST group, which showed exuberant granulation tissue with intense vascularization, and deposition of newly formed collagen fibers (3 and 7 days). It was concluded that the LLLT presented an anti-nociceptive and anti-inflammatory response on the inflammation induced in the temporomandibular joint of rodents., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: A number of problems involving the temporomandibular joint (TMJ) and associated structures can lead to temporomandibular disorder (TMD). The aim of the proposed study is to assess the effect of low-level laser therapy on occlusal contacts, mandibular movements, electromyography activity in the muscles of mastication and pain in adolescents with TMD., Methods/design: A randomized, controlled, double-blind, clinical trial will be carried out involving 85 male and female adolescents between 15 and 18 years of age. The research diagnostic criteria for TMD will be used to assess all individuals who agree to participate. All participants will be submitted to a clinical examination and electromyographic analysis of the masseter muscles and anterior bundle of the temporal muscles bilaterally, to determine TMD. Based on the clinical findings, the participants will be classified as having or not having TMD. Those with TMD will be divided into four groups, three of which will receive low-level laser therapy and one of which will receive a placebo treatment. The treatments will involve the TMJ region alone, the masseter and temporal muscles alone, or both these regions together. The data will be submitted to descriptive statistical analysis. The chi-square test and Fisher's exact test will be used to determine associations among the categorical variables. The Student's t test and analysis of variance will be used for the comparison of mean electromyographic signals. Pearson's correlation coefficients will be calculated for the analysis of correlations among the continuous variables., Trial Registration: The protocol for this study has been submitted to Clinical Trials - registration number NCT01846000.

Purpose: We compared intensity-modulated radiotherapy and 3D-conformal irradiation in oropharyngeal cancers according to the requirement of dentists., Material and Methods: From the files of seven patients with cancer of the oropharynx, two dosimetry plannings for 3D-conformal radiotherapy and intensity-modulated radiotherapy with tomotherapy were performed. The dose distributions in the target volumes and organs at risk in relation to the dental sphere were compared., Results: For the planning target volume of the primitive tumour sites, average values of V95%, D2%, D98% and of the conformal index were statistically in favour of tomotherapy. For the planning target volume of node areas, averages values of V95%, D2%, D98% were statistically in favour of tomotherapy. For ipsi- and controlateral parotide glands, average values of V15Gy, V26Gy, V30Gy, V40Gy were significantly lower for tomotherapy. For the submaxillary glands, average values of mean doses and V40Gy were statistically in favour of tomotherapy. For the buccal cavity, the average values of V45Gy were statistically in favour of tomotherapy. For ipsi- and controlateral masseter muscles, the average values of mean doses were statistically in favour of tomotherapy. For the ipsi- and controlateral temporomandibular joints, average values of mean doses and V60Gy were statistically in favour of tomotherapy. For mandibular bone, average values of mean doses and V40Gy, V50Gy, V60Gy and V70Gy were statistically in favour of tomotherapy. For maxillary bone, average values of V40Gy, V50Gy and V60Gy were statistically in favour of tomotherapy., Conclusion: The radiation oncologist can constrain the intensity-modulated radiotherapy dosimetry to the needs of dentists to prevent or improve dental care and quality of life., (Copyright © 2013 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Background: Radiotherapy to the head and neck regions can result in serious consequences to the temporomandibular joint (TMJ) and chewing muscles. Magnetic resonance imaging (MRI) demonstrates soft-tissue alterations after radiotherapy, such as morphology and signal intensity., Objective: The purpose of this review is to critically and systematically analyse the available evidence regarding the masticatory muscles alterations, as demonstrated on MRI, after radiotherapy for head and neck cancer., Data Sources: Electronic search of MEDLINE, EMBASE, EBM reviews and Scopus., Inclusion Criteria: Reports of any study design investigating radiation-induced changes in masticatory muscles after radiotherapy in patients with head and neck cancer were included., Results and Synthesis Methods: An electronic database search resulted in 162 papers. Sixteen papers were initially selected as potentially relevant studies; however, only four papers satisfied all inclusion criteria. The included papers focused on the MRI appearance of masticatory muscles following radiotherapy protocol. Two papers reported outcome based on retrospective clinical and imaging records, whereas the remaining two papers were case reports. Irradiated muscles frequently show diffuse increase in T2 signal and post-gadolinium enhancement post-irradiation. Also, muscle size changes were reported based on subjective comparison with the contralateral side. The quality of all included papers was considered poor with high risk of bias., Conclusion: There is no evidence that MRI interpretations indicate specific radiation-induced changes in masticatory muscles. There is a clear need for a cohort study comparing patients with pre- and post-radiotherapy MRI.

Purpose: To investigate the relationship between jaw function, patient and treatment variables, and radiation dosimetry of the mandibular muscles and joints in children and young adults receiving radiation for soft-tissue and bone sarcomas., Methods and Materials: Twenty-four pediatric and young adult patients with head-and-neck sarcomas were treated on an institutional review board-approved prospective study of focal radiation therapy for local tumor control. Serial jaw depression measurements were related to radiation dosimetry delivered to the medial and lateral pterygoid muscles, masseter muscles, and temporomandibular joints to generate mathematical models of jaw function., Results: Baseline jaw depression was only influenced by the degree of surgical resection. In the first 12 weeks from initiation of radiation, surgical procedures greater than a biopsy, administration of cyclophosphamide containing chemotherapy regimes, and large gross tumor volumes adversely affected jaw depression. Increasing dose to the pterygoid and masseter muscles above 40 Gy predicted loss of jaw function over the full course of follow-up., Conclusions: Clinical and treatment factors are related to initial and subsequent jaw dysfunction. Understanding these complex interactions and the affect of specific radiation doses may help reduce the risk for jaw dysfunction in future children and young adults undergoing radiation therapy for the management of soft-tissue and bone sarcomas., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: Intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) provides better temporomandibular joint (TMJ) sparing and, thus, may reduce the incidence of radiation-induced trismus after radiotherapy. The objectives of this study were to evaluate radiation-induced trismus in patients with NPC who had received IMRT and to assess the pretreatment factors, relevant treatment factors, and dosimetry parameters associated with trismus., Methods: A prospective, single-arm measurement study with more than 5 years of follow-up was designed. Patients with newly diagnosed stage I through IVB NPC who received treatment with IMRT were eligible. Patients received 66 to 70 grays (Gy) to the gross tumor volume. The maximal interincisal distance (MID) was measured at baseline and 6 months, 1 year, 2 years, 3 years, 4 years, and 5 years after they completed IMRT., Results: The trial enrolled 211 consecutive patients from 2001 to 2004. The mean dose to the TMJ ranged from 6.18 Gy to 51.36 Gy (median dose, 29.88 Gy). Compared with baseline MID levels, normalized MID levels at 6 months, 1 year, 2 years, 3 years, 4 years, and 5 years after IMRT were 94.6% ± 9.9%, 92.5% ± 10.5%, 92% ± 10.6%, 92.2% ± 10.5%, 92.1% ± 10.2%, and 90.3% ± 11.4%, respectively (P < .001). According to a revised subjective-objective management-analytical (SOMA) scale, grade 1/2 trismus was identified in 12 of 211 patients (5.7%), and no grade 3/4 trismus was observed. There was an increasing risk of trismus after IMRT when the MID was <40.5 mm at baseline compared with an MID >40.5 mm (P = .007). No dosimetric parameter was associated with trismus., Conclusions: IMRT was able to reduce the radiation dose to the TMJ and likely reduced the incidence and severity of radiation-induced trismus after radiotherapy., (Copyright © 2011 American Cancer Society.)

Aim: The aim of this study was to evaluate, by light microscopy, the effects of laser phototherapy (LPT) at 780 nm or a combination of 660 and 790 nm, on the inflammatory process of the rat temporomandibular joint (TMJ) induced by carrageen., Background: Temporomandibular disorders (TMDs) are frequent in the population and generally present an inflammatory component. Previous studies have evidenced positive effects of laser phototherapy on TMDs. However, its mechanism of action on the inflammation of the TMJ is not known yet., Materials and Methods: Eighty-five Wistar rats were divided into 9 groups: G1, Saline; G2, Saline + LPT IR; G3, Saline + LPT IR + R; G4, Carrageenan; G5, Carrageenan + LPT IR; G6, Carrageenan + LPT IR + R; G7, previous LPT + Carrageenan; G8, previous LPT + carrageenan + LPT IR; and G9, previous LPT + carrageenan + LPT IR + R, and then subdivided in subgroups of 3 and 7 days. After animal death, specimens were taken, routinely cut and stained with HE, Sirius Red, and Toluidine Blue. Descriptive analysis of components of the TMJ was done. The synovial cell layers were counted., Results: Injection of saline did not produced inflammatory reaction and the irradiated groups did not present differences compared to nonirradiated ones. After carrageenan injection, intense inflammatory infiltration and synovial cell layers proliferation were observed. The infrared irradiated group presented less inflammation and less synovial cell layers number compared to other groups. Previous laser irradiation did not improve the results., Conclusion: It was concluded that the LPT presented positive effects on inflammatory infiltration reduction and accelerated the inflammation process, mainly with IR laser irradiation. The number of synovial cell layers was reduced on irradiated group.

The purpose of this study was to evaluate the analgesic effect of Low Intensity Laser Therapy (LILT) and its influence on masticatory efficiency in patients with temporomandibular dysfunction (TMD). This study was performed using a random, placebo-controlled, and double-blind research design. Fourteen patients were selected and divided into two groups (active and placebo). Infrared laser (780 nm, 70 mw, 60s, 105J/cm2) was applied precisely and continuously into five points of the temporomandibular joint (TMJ) area: lateral point (LP), superior point (SP), anterior point (AP), posterior point (PP), and posterior-inferior point (PIP) of the condylar position. This was performed twice per week, for a total of eight sessions. To ensure a double-blind study, two identical probes supplied by the manufacturer were used: one for the active laser and one for the inactive placebo laser. They were marked with different letters (A and B) by a clinician who did not perform the applications. A Visual Analogue Scale (VAS) and a colorimetric capsule method were employed. Data were obtained three times: before treatment (Ev1), shortly after the eighth session (Ev2), and 30 days after the first application (Ev3). Statistical tests revealed significant differences at one percent (1%) likelihood, which implies that superiority of the active group offered considerable TMJ pain improvement. Both groups presented similar masticatory behavior, and no statistical differences were found. With regard to the evaluation session, Ev2 presented the lowest symptoms and highest masticatory efficiency throughout therapy. Therefore, low intensity laser application is effective in reducing TMD symptoms, and has influence over masticatory efficiency [Ev2 (0.2423) and Ev3 (0.2043), observed in the interaction Evaluations x Probes for effective dosage].

Radiotherapy, when used in head and neck cancer treatment, can produce side effects in the patients, such as decreased salivary production, xerostomia, opportunistic infections, radiation caries, dysphagia, local discomfort and the limitation of mouth opening. The aim of this study was to evaluate the amplitude of mouth opening in patients before and immediately after the completion of radiotherapy, comparing the effectiveness of two physiotherapy exercises. The irradiated sites included the masticatory muscles. The results demonstrated that there were no statistically significant differences between the two instituted exercises; however there was a trend towards better clinical results in group 2. The amplitude of mouth opening showed a trend towards reduction, but this was not statistically significant. When the pterygoid and sternocleidomatoid muscles were included in the irriated field, patients were observed to have more morbidity. This indicates the great importance of these muscles in mouth opening. Based on the results obtained within this study, it is not possible to conclude that physiotherapy exercies are efficacious in preventing trismus. Future longitudinal studies are required to verify the onset of trismus in radiotherapy patients.

Background & Objective: Radiation-induced temporomandibular joint damage is a kind of common complication after radiotherapy for nasopharyngeal carcinoma (NPC) patients. Trimus is the main symptom of this damage, and severely affects the quality of life of the patients. This study was to evaluate radiation-induced temporomandibular joint damage in NPC patients treated with intensity-modulated radiotherapy (IMRT), and analyze its affecting factors., Methods: From Feb. 2001 to Feb. 2003, 148 naive NPC patients were treated with IMRT by 2.27-2.80 Gy per fraction at a total dose of 63-77 Gy within 31-86 days. The distance between 2 dens incisivus medialis (DDIM) was measured before radiotherapy, and 6 months, 1 year, 2 years, and 3 years after radiotherapy, respectively., Results: The overall 1-, 2-, and 3-year survival rates were 97.26%, 94.83%, and 92.04%. The irradiation dose to temporomandibular joint was 17.9-51.36 Gy. Seven (4.73%) patients suffered from grade I-II temporomandibular joint damage after IMRT; no patient had grade III-IV temporomandibular joint damage., Conclusions: IMRT can spare the temporomandibular joint from high dose irradiation. The risk of radiation-induced severe temporomandibular joint damage in NPC patients after IMRT is low.

The effects of irradiation and hyperbaric oxygenation (HBO) on the extracellular matrix of condylar cartilage after mandibular distraction were evaluated. Unilateral distraction was performed on 19 rabbits. Five study groups were included: control, low- and high-dose irradiation, and low- and high-dose irradiation groups with HBO. Additionally, four temporomandibular joints (TMJ) were used as control material. The high-dose irradiated animals were given in the TMJ 22.4 Gy/4 fractions irradiation (equivalent to 50 Gy/25 fractions). Low-dose irradiation group received a 2.2 Gy dosage. Two groups were also given preoperatively HBO 18 x 2.5ATA x 90 min. After a two-week distraction period (14 mm lengthening) and four-week consolidation period the TMJs were removed. Proteoglycan (PG) distribution of the extracellular matrix was evaluated using safranin O staining and collagen I and II using immunohistochemistry. The organization of fibrillar network was studied by polarized light microscopy. On the operated side of the control group and on the unoperated side in all, except for high-dose irradiated group, PG distribution and fibrillar network were normal appearing. In the irradiated groups, with or without HBO, the cartilaginous layer was partially or totally devoid of PG and the network structure was severely damaged. In conclusion, irradiation in conjunction with the pressure applied by distraction causes severe damage to extracellular matrix of condylar cartilage.

Objective: The aim of the present study was to evaluate the facial thermographic changes before and after low-level laser irradiation applied to the temporomandibular joint in normal subjects., Background Data: Although this therapy has been reported to be effective in the pain management of patients with rheumatoid arthritis and degenerative joint disease, several researchers have stated that this therapy has no effect on pain of myogeneous origin., Materials and Methods: Nine healthy subjects underwent irradiation using the continuous wave setting of a CO2 laser with a power output of 1.0 W. The laser tip was positioned 10 cm above the skin over the right TMJ area for 10 min. The actual fluence on the facial surface was 7.64 J/cm2. Variation of the facial temperature was evaluated by using thermography., Results: The facial temperature 10 min after stopping irradiation was higher than that after 10 min of irradiation applied to the opposite side. The warmer area was found not only over the TMJ area but also over the temporal area, forehead area, and eyelid area on both sides., Conclusion: These results suggested that low-level laser irradiation had a long-lasting effect on facial cutaneous tissues.

The purpose was to evaluate the effect of mandibular distraction osteogenesis (DO) on condylar cartilage after radiotherapy and hyperbaric oxygenation (HBO). Unilateral DO was performed on low- and high-dose irradiated rabbits with or without accompanying HBO, and non-irradiated animals. High-dose irradiated animals were given irradiation in the temporomandibular joint (TMJ) equivalent to 50 Gy in 25 fractions. Low-dose irradiated rabbits received scattered irradiation of 10% of that of high-dose irradiated animals. After radiotherapy, some of the animals were given HBO 18 times at 2.5 ATA for 90 min/day. One month after completion of radiotherapy, distraction osteotomy with distractor placement was performed. After a latency period, distraction was started at the rate of 1 mm/day, continued for 2 weeks, and the regenerate was allowed to consolidate for 1 month. Condyles of non-operated rabbits served as controls. Histological changes were more evident on the distracted than on the non-distracted side. In distracted, non-irradiated animals, condylar cartilage changes were minor and probably clinically insignificant. In irradiated rabbits, condylar cartilage changes on the lengthened side were severe, and often cartilage was either totally or partially sealed off by bone. Condylar heads were morphologically deformed. Even low doses of irradiation resulted in notable changes on the operated side, and HBO did not prevent disadvantageous effects.

The purpose of the study was to evaluate the effects of irradiation and hyperbaric oxygenation (HBO) on osteoblastic activity of the temporomandibular joint (TMJ) region during mandibular distraction osteogenesis. Unilateral distraction was performed on 19 rabbits, which were divided into five groups. One group served as a control group, while the others received either high- or low-dose irradiation in the TMJ region before surgery. Some of the animals were also given HBO 18 times at 2.5 ATA x 90 min preoperatively. Osteogenesis was assessed by [18F]fluoride positron emission tomography at the end of the distraction. Osteoblastic activity was higher on the distracted side in all groups, except in the high-dose irradiated group without preceding HBO. HBO increased osteogenesis on both sides after radiotherapy. It is concluded that increased osteoblastic activity reflects increased pressure on the TMJ region of the distracted side, resulting from lengthening. It seems that more remodeling is required after irradiation than without preceding radiotherapy. After radiotherapy, HBO increased osteoblastic activity.

Background and Purpose: The aim of this study is to evaluate and delineate the deficiencies in conventional two-dimensional (2-D) radiotherapy planning of nasopharyngeal carcinoma (NPC) treatment and to explore the means for improvement of the existing treatment technique aiming at enhancing local tumor control and reducing treatment complications., Methods and Materials: Ten patients with NPC sparing the skull base and without intracranial extension or cranial nerve(s) palsy were chosen in the present study. Two sets of CT images for Phases I and II of the radiotherapy treatment were taken with patient immobilized in the flexed-head and the extended-head positions, respectively. Based on the CT images and endoscopic findings, the gross tumor volume (GTV) was defined. The clinical target volume (CTV) circumscribing the GTV was defined according to Ho's (Halnan, K.E. (ed.) Treatment of Cancer. London: Chapman and Hall, 1982. pp. 249-268) description of the organs at risk of tumor infiltration. The planning target volume (PTV) was defined by adding a margin to the CTV which catered for geometrical inaccuracies. The field borders and shields were set at standard distances from certain bony landmarks and were drawn on the simulator radiograph. Data on the beams and shield arrangements were then transferred to the planning computer via a digitizer. By applying 3-D volumetric dose calculation using a commercial three-dimensional (3D) treatment planning computer, the dose-volume-histograms (DVHs) of GTV, CTV, PTV and critical normal organs were generated for both phases of Ho's treatment technique. The same patients were re-planned using a modified Ho's technique which used 3-D beams-eye-view (BEV) in placing the shielding blocks and the same set of DVHs were generated and compared with those obtained from Ho's technique., Results: The median volumes of GTV, CTV and PTV covered by the 95% isodose in Ho's phase I treatment were around 60%. The dose coverage was unsatisfactory in the superior and inferior and the posterolateral regions. In phase II treatment, the median volume of GTV, CTV and PTV covered by the 95% isodose were 99, 96 and 72%, respectively. Even though the dose coverage of the PTV in both phases of treatment were unsatisfactory, radiotherapy with the original Ho's technique had consistently produced good local control for NPC. However, there is potential room for enhancing the local control further because after modifying Ho's technique by using 3-D BEV customization of the treatment portals, the median volume of the target covered by the 95% isodose was defined as V(95). The V(95) of the PTV during the Phase II treatment was improved by 13%. The 90% of the volume of temporo-mandibular joints and parotid glands were both irradiated to 53 Gy and 43.6 Gy of the total prescribed dose of 66 Gy, respectively, in phase I and II treatments. With the addition of a hypothalamus-pituitary shield to Ho's technique, 50% of the volume of optic chiasma and temporal lobes received, respectively, 19.3 Gy and 4.5 Gy. However, small volume of the temporal lobes received a maximum dose (D(max)) of 62.8 Gy (95.2% of 66Gy). Most of the brainstem was shielded from the lateral portals but 5% of its volume received a dose ranging from 25.4 to 50.4Gy. The spinal cord (at C1/C2 level) received a D(max) of 40.8 Gy in phase I and of 4.8 Gy in phase II. After modifying Ho's technique by 3-D BEV customization of the treatment portals, the D(max) to the brainstem, the optic chiasma and the temporal lobes could be reduced by 8, 12 and 5%, respectively., Conclusions: Our study indicated that the dose-coverage of the PTV in Ho's radiotherapy technique for the early T-stage NPC was less than satisfactory in the superior and inferior and the posterolateral regions. However, in view of the excellent historical local tumor control with Ho's technique, we have to postulate that the present definition of CTV (and hence the PTV after adding margins to the CTV) lacks clinical significance and can be improved. It appears that the inclusion of the entire sphenoid sinus floor and both medial and lateral pterygoid muscles in the CTV is not necessary for maximal tumor control in the absence of clinical/radiological evidence of tumor infiltration of these organs. Ho's technique can be improved by using 3-D BEV to customize the treatment portals with multileaf collimators or blocks.

Objectives: To estimate the radiation-related risk associated with twelve imaging programs available on the Orthophos (Siemens, Erlangen, Germany) dental panoramic radiography unit., Methods: Organ absorbed doses for each program were measured using a Rando anthropomorphic phantom loaded with thermoluminescent dosemeters. Effective dose (E) was calculated in two ways; first, using the method recommended by the International Commission on Radiological Protection, which excludes the salivary glands (designated Eexc), and second, with its inclusion (designated Einc). Organ and effective doses were both used to compare the various imaging programs., Results: In 11 of the 12 programs studied the salivary glands received the highest individual organ dose, and Einc was found to be up to double Eexc. When the image was restricted to the dentition (program 2) organ doses were lower than for the complete jaws (program 1) by up to 85%, and Eexc and Einc reduced by about one half. When programs 2 and 6 (to image the temporomandibular joints) are used in place of program 1, the former combination provides more image information at an equivalent risk., Conclusions: The value of E in panoramic radiography depends on the inclusion of the salivary glands in the calculation and the magnitude of the dose.

Objective: The purpose of this study was to analyze the effects of head and neck radiation therapy on jaw opening and mobility., Study Design: Maximum jaw opening and mandibular mobility were measured before and after radiation treatment in 58 patients presenting for angle down wedge, homolateral wedge pair, and parallel pair head and neck radiation treatment., Results: As dose to the temporomandibular joint and pterygoid muscles increased, maximal jaw opening decreased linearly. Mandibular dysfunction appeared to increase as radiation dose to the pterygoid muscles increased. Similar effects were not observed with temporomandibular joint irradiation. Irradiation of the pterygoid muscles appeared critical in the development of trismus. Angle down wedge treatment irradiated the temporomandibular joint and pterygoid muscles with clinical effects similar to those seen in homolateral wedge pair and parallel pair patients. Doses as low as 1493 cGy resulted in functional impairment., Conclusions: Future investigations into radiotherapy delivery and appropriate postradiation trismus treatment may reduce head and neck radiation morbidity.

By means of light and electronic microscopy the state of tissues of the temporomandibular joint synovial coat was examined in dogs. As a results a model of aseptic inflammation of temporomandibular joint was created (the first series of experiments), the impact of different dozes of helioneonic laser on intact tissues was studied and the most efficient doze of irradiation was established (the second series of experiments). On the third series it was shown that the doze of irradiation chosen influences positively the structural changes in synovial coat, caused by the aseptic inflammation.

Purpose: The efficacy and toxicity of radiation therapy used for preventing re-formation of heterotopic bone involving the temporomandibular joint are assessed., Methods and Materials: Ten patients (15 TMJs) with bony ankylosis of the TMJ were referred after reconstruction with costochondral graft, gap arthroplasty, or debridement of heterotopic bone. Treatment consisting of 10 Gy was delivered early postoperatively to a field encompassing the TMJ with adequate margin. Response to therapy was assessed by comparison of routine roentgenograms obtained preoperatively, immediately postoperatively, and at last follow-up; the Turlington-Durr grading system was used. Median duration of postoperative follow-up was 19 months., Results: Radiation therapy prevented ectopic bone re-formation in 10 (69%) of 15 TMJs with prior bony ankylosis. Of the 15 TMJs, 13 (87%) had improvement in their Turlington-Durr scores compared with the preoperative scores. Development of ectopic bone formation was prevented in 9 (90%) of 10 TMJs rendered Turlington-Durr grade 0 postoperatively. Eight of the 10 patients have remained asymptomatic. Treatment was well tolerated. The only complication experienced was parotitis in three patients., Conclusion: Radiation therapy is useful for prevention of heterotopic bone redevelopment after TMJ operation. We recommend 10 Gy in 5 fractions beginning early postoperatively for high-risk patients. This strategy appears beneficial in this young patient population, who suffer significant pain and functional impairment in the TMJ articulation.

A retrospective analysis was undertaken of the late complications observed in 4527 patients with nasopharyngeal carcinoma treated by megavoltage radiotherapy during the years 1976-1985. Unconventional fractionation schedules were used because of serious resource limitations. The median equivalent doses were 65 Gy to the nasopharyngeal region and 53 Gy to the cervical region. 707 patients had reirradiation for local recurrences and 250 for regional relapses. The 10-year actuarial cancer-specific survival was 47%, and the corresponding all-complication-free and neurological-complication-free rates were 40% and 72%, respectively. Altogether, 1395 (31%) patients developed one or more late irradiation sequelae. The majority were mild soft-tissue damages, but 322 (7%) had significant functional disturbances, from which 62 (1%) died. Neurological damage that occurred in 450 (10%) patients constituted the major morbidity and accounted for all but three of the treatment mortalities. The cumulative incidence of the various complications is summarized, and the data recorded in the literature reviewed in order to give a proper perspective of the problem. Patients treated during 1981-1985 had a significantly higher actuarial encephalomyelopathy-free rate than those treated during 1976-1980, but the incidence-free rates for the other neurological complications remained unimproved, suggesting that the improvement could be mainly attributed to additional shielding for the brainstem rather than the reduction of dose from 3.8-4.2 Gy to 2.5 Gy per fraction.

Thermoluminescent dosimeters were used in a tissue-equivalent phantom to measure doses of radiation absorbed by various structures in the head when the temporomandibular joint was examined by four different radiographic techniques--the transcranial, transorbital, and sigmoid notch (Parma) projections and the lateral tomograph. The highest doses of radiation occurred at the point of entry for the x-ray beam, ranging from 112 mrad for the transorbital view to 990 mrad for the sigmoid notch view. Only the transorbital projection a radiation dose to the lens of the eye. Of the four techniques evaluated, the lateral tomograph produced the highest doses to the pituitary gland and the bone marrow, while the sigmoid notch radiograph produced the highest doses to the parotid gland.

Weighting of given doses from parallel opposed fields is a widespread practice in radiation therapy of cancer in the tonsillar region. In order to determine when weighting is useful, dose distributions on the central axis were calculated for various energies (60Co, 4-, 8-, 15-, and MVp photons), weighting factors, and field separations. Criteria for judging the usefulness of weighting were (i) that variation in the dose across the tumor volume not exceed 10%, and (ii) that the dose to critical tissues outside the target volume be at least 20% less than target volume dose. The clinical situation that met these criteria was a lateral lesion that extended to less than one-third of the transverse diameter of the head, treated with either 60Co, 8, or 4 MVp with 4:1 weighting. Under these conditions, weighting was considered to be justified.

A neodymium:yttrium aluminum garnet (Nd:YAG) laser beam was introduced by a quartz fiber passed arthroscopically into the superior joint space of the temporomandibular joints (TMJ) of five mongrel dogs, with one joint serving as a control without laser wounds. Immediate postoperative death and examination of the disc grossly and histologically revealed different patterns for contact and noncontact burn wounds. The wounds exhibited signs of thermal coagulation necrosis similar to those reported in other tissues. The potential implications of the adaptation of the Nd:YAG laser to TMJ arthroscopic surgery are discussed.

According to a report by Poretti (1975) 21,4% of all medical diagnostic radiographs in Switzerland are dental. In order to determine the associated radiation doses to patients, phantom measurements of skin and gonad exposures were made utilizing modern dental x-ray equipment and techniques. Following procedures in accordance with federal safety regulations it was not possible to measure dose values at the gonad level by single dental or temporomandibular radiographs, even by the most sensitive measuring device. 50 cumulative exposures without lead apron resulted in a range of gonad doses from 3.1 to 199 microR for dental and temporomandibular joint x-rays. Results of skin surface doses ranged from 38 to 289 mR for single dental film exposure and from 64 to 494 mR for single TMJ exposures. Consistent use of parallel technique with long cone equipment, small diaphragms, high kilovoltage and use of the lead apron guarantee great safety against radiation hazard in dental radiography.

This is the first reported case of the use of cobalt 60 radiation for the prevention of recurrent TMJ ankylosis after repeated surgical treatment had failed. Although radiation therapy is not usually indicated for benign conditions, 2,000 rads can be used safely to treat this crippling condition. Although no conclusions can be drawn from a single case, successful treatment of this patient is indicated by a 3 1/2-year follow-up.

Lateral transcranial radiographs are commonly used to evaluate TMJ morphology and function. This study evaluated the use of four TMJ positioners in controlling the amount of radiation absorbed at predetermined sites on a phantom head. Use of positioners and collimators can reduce the amount of radiation exposure.