Systemic Effects of Photobiomodulation on the Morphology of the Thyroid and Sublingual Glands: A Study in Rabbits.

Objective: To investigate whether photobiomodulation (PBM) applied in a clinical situation with the purpose of improving the healing process of implants placed in the rabbit mandible would cause any morphological change in the thyroid and sublingual glands as a systemic effect of laser irradiation. Methods: Thirty-two New Zealand rabbits were randomly divided into four groups of eight animals each, one control group (CI, nonirradiated animals) and three experimental groups (EI, EII, and EIII) that received PBM postoperatively with an aluminum/gallium/arsenide laser diode (Theralase®) at a wavelength of 830 nm (infrared) and 50 mW output power applied to two irradiation fields per session, for a total of seven sessions. All rabbits underwent surgical extraction of the mandibular left incisor, followed by immediate placement of an osseointegrated implant in the fresh socket. The experimental groups EI, EII, and EIII received PBM at an energy density of 5, 2.5, and 10 J/cm2, respectively, per irradiation field. Results: There was no histomorphometric change in any of the groups. Conclusions: PBM, based on the irradiation protocol used in this study, does not cause morphological changes in the thyroid and sublingual glands when used to stimulate peri-implant bone healing in the rabbit mandible.

Use of low-level laser therapy on children aged 1 to 5 years with energy-protein malnutrition: A clinical trial.

BACKGROUND: Episodes of malnutrition in early childhood can produces alterations in the salivary glands. The investigation of mechanisms that can reduce the impact of malnutrition on the defenses of the organism is of the utmost important and interest to public health. The aim of this study is to evaluate the effect of low-level laser on the saliva of children aged 1 to 5 years with energy-protein malnutrition. METHODS: Mandatory inclusion criteria are diagnosis of malnutrition. The sample will consist of 50 men and women malnourished children aged 12 to 71 months. Saliva will be collected and the volume of saliva will be measured and the salivary flow rate will be determined (mL/min). Concentrations of salivary IgA in all samples will be measured using a commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit. Low-level laser (laser diode) will be administered in the region of the parotid glands bilaterally as well as in the regions of the submandibular and sublingual glands. DISCUSSION: This study will be the first that investigate the effects of local laser therapy on the salivary glands of malnourished children. TRIAL REGISTRATION: Clinical.trials.gov as NCT03355313, first received in 21 November 2017.

A functional and chemical study of radiation effects on rat parotid and submandibular/sublingual glands.

The aim of this study was to monitor composition and rate of secretion of rat parotid and submandibular/sublingual saliva following local single doses of X-rays ranging from 5 to 20 Gy. Pilocarpine-stimulated samples of parotid and submandibular/sublingual saliva were simultaneously collected with miniaturized Lashley cups before and 1-30 days after irradiation. The lag phase (period between injection of pilocarpine and start of the secretion) and flow rate were recorded and the concentrations of sodium, potassium, calcium, phosphate, and amylase were measured. With increasing dose and time, the salivary flow rate as well as sodium concentration decreased, while potassium concentrations increased throughout the follow-up period. The lag phase and the concentration of amylase reached their maximum at 3 and 10 days after irradiation, respectively. The changes in lag phase and flow rate were most obvious after doses of 15 or 20 Gy and showed a great similarity for parotid and submandibular/sublingual saliva. No dose-response relationship was observed for the changes in concentrations of calcium and phosphate. It is concluded that for radiation doses of 10 Gy and above, irreversible changes (lag phase, flow rate, potassium, sodium) were observed. A saturation of the irradiation effects (lag phase, flow rate) seems to exist at doses larger than 15 Gy. No significant differences were observed between the radiation-induced functional changes in parotid and submandibular/sublingual salivary gland tissue.

Acute effects of X irradiation on the function of rat salivary glands.

Radiation-induced damage to salivary glands has been recognized for over 80 years. However, the mechanisms responsible for the destruction of gland parenchyma are still not known. The purpose of this study was to describe alterations in salivary function in the rat within the first 24 h after irradiation. Saliva was collected from the parotid and submandibular glands during radiation treatment and at four times (0.5, 1, 4, and 24 h) after 15 Gy X irradiation delivered to the head and neck. Total body weight, submandibular gland weight, and food and water intake were monitored and the total protein, sodium, and potassium content of the salivas was analyzed. The effects of radiation on salivary glands of the rat could be demonstrated by 24 h. Parotid salivary flow was reduced and the sodium concentration was significantly less than that in control animals. Submandibular gland weights declined markedly by 24 h. These effects appear to be influenced significantly by the animals' limited intake of food and water during this period, as well as the anesthesia administered.

Sialogogue-related radioprotection of salivary gland function: the degranulation concept revisited.

To investigate whether secretory granules play a role in the radiosensitivity of the salivary glands of rats, parotid acinar cells, submandibular acinar cells and/or submandibular granular convoluted tubule (GCT) cells were degranulated prior to irradiation. Degranulation of GCT cells was obtained by pretreatment with phenylephrine (5 mg/kg, t = -60 min) and methacholine (3.75 mg/kg, t = -120 min). Degranulation of acinar cells was attained by pretreatment with isoproterenol (5 mg/kg, t = -90 min). Combinations of pretreatments were also tested. Irradiation was performed with a single dose of 15 Gy of X rays. Samples of parotid and submandibular/sublingual saliva were collected 4 days prior to and 1, 3, 6, 10 and 30 days after irradiation. Pretreatment with phenylephrine, isoproterenol and methacholine plus phenylephrine resulted in less radiation damage to parotid gland function as indicated by the lag phase and flow rate. Since the pretreatment with phenylephrine and phenylephrine plus methacholine did not degranulate parotid gland acinar cells, the observed protective effect on this gland cannot be explained by the "degranulation concept." Furthermore, salivary gland function was significantly greater 3 days after irradiation as a result of pretreatment with phenylephrine and phenylephrine plus methacholine compared to rats given only radiation. This may indicate recovery from damage rather than a reduced amount of initial damage. The sparing was most obvious for the later effects (6-30 days). Submandibular/sublingual gland function was improved significantly after pretreatment with methacholine plus phenylephrine, although no increase in degranulation of GCT cells was observed compared to pretreatment with phenylephrine alone, again not favoring the degranulation concept. The results indicate that the secretory granules do not play the often-assumed important role in the radiosensitivity of the salivary gland. The mechanism underlying the observed improvement of salivary gland function may involve second messenger-induced increases in proliferation of salivary gland cells resulting in recovery of tissue after the irradiation.

Bombesin-like peptide is present in duct cells in salivary glands: studies on normal and irradiated animals.

Bombesin (BN) and its mammalian counterpart gastrin-releasing peptide act as neuroregulatory hormones and tissue-specific growth factors, and have been implicated as peripheral and central satiety-inducing agents. In the present study, the immunohistochemical expression of BN in submandibular, sublingual and parotid glands of rats was examined 10 days after 5 consecutive days with daily doses of 6-8 Gy irradiation. Radioimmunoassay (RIA) methods were also used. Immunoreactive granular structures were observed within duct cells of both controls and irradiated animals. In the parenchyma of irradiated animals, very few nerve fibres showing BN-like immunoreactivity were observed. The RIA analysis showed that the content of BN-like material significantly increased in submandibular and parotid glands in response to irradiation. The results suggest that mainly a non-neural form of BN is detected in the salivary glands in the immunohistochemical analysis. Thus, the immunohistochemical observations suggest that BN-like peptides may be present in the duct system, where they may be constituents of the saliva. The observations of an increase in BN content in response to irradiation are of interest as BN has mitogenic effects, may stimulate secretion and contributes to satiety.

[Salivary gland scintigraphy after radio-iodine therapy. Functional scintigraphy of the salivary gland after high dose radio-iodine therapy (author's transl)]. / Funktionsszintigraphie der Speicheldrüsen nach hochdosierter Radiojodtherapie. Laufender Titel: Speicheldrüsenszintigraphie nach Radiojodtherapie

Following high dose radio-iodine therapy, some radiation damage to the salivary glands is to be expected since iodine is taken up by these glands. The great individual variation in the uptake makes it impossible to predict the severity of the damage. T max and maximal excretion capacity after stimulation were therefore estimated by a camera functional scintigram with digital read out in patients following radioiodine therapy (0.1-3.2 Ci); the excretion index was used as an indirect measure of salivary flow. After a dose up to 0.3 Ci there is a change of T max and maximal excretion capacity in 30% of patients; after a dose of 0.5 to 1 Ci it is found in 60 and 80% and after very high doses of 1.1 to 3.2 Ci an abnormal Tmax was found in two-thirds of all patients and reduced or absent excretion capacity in all nine patients in this group. The excretion index also depended significantly on the cumulative dose. All patients who had received very high doses showed marked hyposialia or asialia. The early results of interim examinations suggest, similar to radio-iodine induced hypothyroidism, a cumulative risk of reduced function. In view of the long survival period of patients with differentiated thyroid carcinomas attention should be drawn to this side effect.

Neuron-specific enolase reduction in irradiated salivary glands of the rat--an immunohistochemical study.

Neuron-specific enolase (NSE) in the salivary glands of normal and irradiated rats was studied by immunohistochemical methods. The normal salivary gland of Sprague-Dawley rats (465 g) showed positive staining for NSE in striated ducts and granular convoluted tubule (GCT) cells. A single radiation, TDF (time, dose, fractionation factor) 100 and 200 (18.82 Gy and 27.97 Gy, respectively) was done, and 4 groups (1, 2, 3 and 4 weeks after radiation) of 5 rats each were used. Irradiated salivary glands indicated a remarkable reduction of NSE staining in GCT cells and a reduction but to a lesser degree in the striated duct of the submandibular gland. Immunohistochemical deposition of NSE was not changed in the sublingual glands of irradiated rats. The reduction of NSE immunodeposition was irradiation dose dependent.

Tissue radiation dosages using the RVG-S with and without niobium filtration.

Tissue doses for a modified Rando head- and-neck phantom were measured for imaging with speed group E film with standardized aluminium filtration and the RVG-S both with and without added niobium filtration. Cylindrical holes drilled into the phantom's tissue-equivalent material permitted the placement of a small ionization chamber into anatomically correct sites representing the thyroid, parotid, submandibular and sublingual glands. To establish the necessary cone positions, angulations and time settings for each exposure, diagnostically acceptable images of six teeth, representative of different intraoral regions, were made for a DXXTR mannequin. Entrance and exit points were marked and transferred to the phantom to allow reproducible repeat exposures. The RVG-S provided reductions in average skin entrance dose of 31 per cent to 39 per cent with standard aluminium filtration and 51 per cent to 60 per cent with the addition of niobium filtration to attenuate the beam. While dose reductions relative to E-speed film usage were found for deep tissue sites, these were site and projection specific. The cumulative reduction from use of the RVG-S without niobium filtration was 32 per cent. It was 42 per cent with additional niobium filtration. It should be noted, however, that adding niobium filtration resulted in increased dosages to the deeper soft tissues such as the thyroid gland.

Effective dose span of ten different cone beam CT devices.

OBJECTIVES: Evaluation and reduction of dose are important issues. Since cone beam CT (CBCT) has been established now not just in dentistry, the number of acquired examinations continues to rise. Unfortunately, it is very difficult to compare the doses of available devices on the market owing to different exposition parameters, volumes and geometries. The aim of this study was to evaluate the spans of effective doses (EDs) of ten different CBCT devices. METHODS: 48 thermoluminescent dosemeters were placed in 24 sites in a RANDO(®) head phantom. Protocols with lowest exposition parameters and protocols with highest exposition parameters were performed for each of the ten devices. The ED was calculated from the measured energy doses according to the International Commission on Radiological Protection 2007 recommendations for each protocol and device, and the statistical values were evaluated afterwards. RESULTS: The calculation of the ED resulted in values between 17.2 µSv and 396 µSv for the ten devices. The mean values for protocols with lowest and highest exposition parameters were 31.6 µSv and 209 µSv, respectively. CONCLUSIONS: It was not the aim of this study to evaluate the image quality depending on different exposition parameters but to define the spans of EDs in which different CBCT devices work. There is a wide span of ED for different CBCT devices depending on the selected exposition parameters, required spatial resolution and many other factors.

Using a reduced spot size for intensity-modulated proton therapy potentially improves salivary gland-sparing in oropharyngeal cancer.

PURPOSE: To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could further reduce the parotid and submandibular gland dose compared with previously calculated IMPT plans with a larger spot size. In addition, it was investigated whether the obtained dose reductions would theoretically translate into a reduction of normal tissue complication probabilities (NTCPs). METHODS: Ten patients with N0 oropharyngeal cancer were included in a comparative treatment planning study. Both IMPT plans delivered simultaneously 70 Gy to the boost planning target volume (PTV) and 54 Gy to the elective nodal PTV. IMPT and rsIMPT used identical three-field beam arrangements. In the IMPT plans, the parotid and submandibular salivary glands were spared as much as possible. rsIMPT plans used identical dose-volume objectives for the parotid glands as those used by the IMPT plans, whereas the objectives for the submandibular glands were tightened further. NTCPs were calculated for salivary dysfunction and xerostomia. RESULTS: Target coverage was similar for both IMPT techniques, whereas rsIMPT clearly improved target conformity. The mean doses in the parotid glands and submandibular glands were significantly lower for three-field rsIMPT (14.7 Gy and 46.9 Gy, respectively) than for three-field IMPT (16.8 Gy and 54.6 Gy, respectively). Hence, rsIMPT significantly reduced the NTCP of patient-rated xerostomia and parotid and contralateral submandibular salivary flow dysfunction (27%, 17%, and 43% respectively) compared with IMPT (39%, 20%, and 79%, respectively). In addition, mean dose values in the sublingual glands, the soft palate and oral cavity were also decreased. Obtained dose and NTCP reductions varied per patient. CONCLUSIONS: rsIMPT improved sparing of the salivary glands and reduced NTCP for xerostomia and parotid and submandibular salivary dysfunction, while maintaining similar target coverage results. It is expected that rsIMPT improves quality of life during and after radiotherapy treatment.

Effect of defocused infrared diode laser on salivary flow rate and some salivary parameters of rats.

This study aims to investigate whether infrared diode low-level laser therapy (LLLT) increased salivary flow rate and altered pH value, protein concentration, and peroxidase and amylase activities in saliva of rats. Wistar rats were used and divided into three groups. Experimental groups (A and B) had their parotid, submandibular and sublingual glands submitted to diode laser, 808-nm wavelength, on two consecutive days. The dose results were 4 and 8 J/cm(2), respectively. A red guide light was used to visualize the irradiated area. Group C was irradiated only with red pilot beam and served as control. The saliva samples were collected after each irradiation step (first and second collection days) and 1 week after the first irradiation (seventh day). Statistical analysis was performed, and differences were observed according to different days of salivary collection. The results showed that salivary flow rate for groups A and B was higher on the seventh day if it is compared to data obtained for the first day (p < 0.05). LLLT applications on salivary glands are a therapy procedure that requires further studies.

[Absorbed doses to critical organs from full mouth dental radiography].

OBJECTIVE: A few studies were reported in China on radiological risk of dental radiography. The aim of this study is to evaluate the absorbed doses of patients from the full mouth radiographs, and to find out the contribution from each projection to the total absorbed dose of the organs. METHODS: Absorbed doses to critical organs were measured from 14-film complete dental radiography. The organs included pituitary, optical lens, parotid glands, submandibular glands, sublingual glands, thyroid, breasts, ovary, testes and the skin in center field of each projection were studied. A-radiation analog dosimetry system (RANDO) phantom with thermoluminescent dosimeters (ILD200) was used for the study. All of the exposure parameters were fixed. The total filtration was 2 mm Al equivalent. The column collaboration was 6 cm in diameter and 20 cm in length. The absorbed doses of organs were measured three times in each projection of the full-mouth series (FMS) exposures. RESULTS: The absorbed dose of lenses in FMS (249 microGy) in present study was much less (10%) than the doses (2,630 microGy) reported in 1976. The doses absorbed of other organs in the present study were thyroid gland (125 microGy), pituitary gland (112 microGy), parotid gland (153 microGy), submandibular gland (629 microGy), sublingual gland (1,900 microGy), and breast gland (12 microGy). The doses of the ovary and testis were to small to further analysis. CONCLUSION: All of the results show that the radiation risk to patients in intraoral radiograph has been reduced significantly. In the pituitary, half of the dose is from both sides of the maxillary molar projection. For the lenses, the largest contribultions of radiation (60%) come from the ipsilateral molar and premolar projection of maxilla. In parotid gland, up to 57% of the dose is from the contralateral molar, pre-molar and canine of maxilla. It could be derived that about 90% of the absorbed doses could be avoided in FMS if the column collimator is 20 cm long and the filter is 2.0 mm thick. If we use the 10-film complete mouth radiograph instead of the 14-film series, more 20% of the doses would be reduced.

Irradiated salivary glands in the rhesus monkey. A light microscopic study.

Female rhesus monkeys (Macaca mulatta) received fractionated doses of orthovoltage irradiation to the submandibular and sublingual glands. Changes in the glands varied from serous cell degranulation and degeneration in the submandibular glands to acinar cell necrosis and fibrosis in the sublingual glands. Acute inflammation was absent in all irradiated glands. In all glands, the microvasculature appeared normal.

Sparing of contralateral major salivary glands has a significant effect on oral health in patients treated with radical radiotherapy of head and neck tumors.

BACKGROUND: Has a conscious exclusion of the contralateral major salivary glands (parotid, submandibular, and sublingual glands) a significant impact on the milieu of the oral cavity (saliva flow, pH, buffer capacity, and colonisation with Streptococcus mutans) in patients with ENT tumors receiving radical radiotherapy? PATIENTS AND METHODS: 20 consecutive consenting patients with ENT tumors were evaluated once before, weekly during, and 6 weeks after the end of treatment in regard to saliva flow, ph, buffer capacity, and colonisation with Streptococcus mutans. In 13 patients the major salivary glands on both sides were included in the treated volume, in seven patients the treatment portals excluded consciously the contralateral major salivary glands. RESULTS: The stimulated saliva flow decreases already during the 1st week of radiotherapy, the decrease follows the dose exponentially; the saliva flow is further reduced in the weeks after the end of treatment. The effect is less pronounced in patients with sparing of contralateral major salivary glands. The majority of patients with unilateral sparing of the major salivary glands retain the baseline value of buffer capacity, whereas buffer capacity of all patients with inclusion of all major salivary glands is markedly reduced with 20 Gy already, without signs of recovery when treatment has stopped. With unilateral salivary gland sparing the pH always remains basic, in bilaterally irradiated patients the pH changes from a mean of 7.3 to 5.8 during treatment. The colonisation with Streptococcus mutans varies little in both groups during the radiotherapy; after the end of therapy, it is higher in bilaterally irradiated patients. CONCLUSIONS: The conscious arrangement of irradiation portals in order to spare contralateral major salivary glands in patients with radical radiotherapy of ENT tumors has a significant influence on the oral environment: the stimulated saliva flow is higher, the buffer capacity retains the baseline value, the saliva pH remains basic, and the colonisation with Streptococcus mutans is reduced.

Histochemical changes in the digestive tract in irradiated rats.

Wistar rats (110-125 g) were irradiated with a single dose of 500 R. Histochemical studies were done concerning the glycoproteins (GP) of sublingual glands, gastric, small intestine and colon mucosa, and some intestinal enzymes: acid and alkaline phosphatase (ACP, ALP) leucineaminopeptidase (LAP), Mg-dependent ATP-ase, NADH-diaphorase, lactic dehydrogenase (LDH). After irradiation all these reactions were diminished, with a maximal effect between 3-5 days. This impairment is in accord with the maximal lethality in this interval after such a degree of irradiation that produced the gastrointestinal syndrome. Cocarboxylase, a radioprotector, improved these changes regarding the structures of the small intestine and also the GP of sublingual glands, stomach, small intestine and colon, demonstrating there its efficiency.