Effect of radiofrequency electromagnetic fields (RF-EMFS) from mobile phones on nickel release from orthodontic brackets: An in vitro study.

BACKGROUND: The worldwide dramatic increase in the use of cell phones has generated great concerns about their potential adverse health effects. OBJECTIVE: The aim of the present study was to evaluate the effects of radiofrequency electromagnetic fields (RF-EMFs) emitted from mobile phones on the level of nickel release from orthodontic brackets. METHODS: Twenty stainless steel brackets were divided randomly into experimental and control groups (n=10). Brackets were immersed in artificial saliva at 37°C for 6 months. Experimental group were exposed to GSM 900MHz RF-EMFs emitted from a mobile phone stimulator for 4hours. The specific absorption rate (SAR) was 2.287W/kg. The concentration of nickel in the artificial saliva in both groups was evaluated by using the cold-vapour atomic absorption spectrometry. The Mann-Whitney test was used to assess significant differences in nickel release between the exposed and non-exposed groups. RESULTS: The mean nickel levels in the exposed and non-exposed groups were 11.95 and 2.89µg/l, respectively. This difference between the concentrations of nickel in the artificial saliva of these groups was statistically significant (P=0.001). CONCLUSION: Exposure to RF-EMFs emitted from mobile phones can lead to human exposure to higher levels of nickel in saliva in patients with orthodontic appliances. As nickel exposure can lead to allergic reaction in humans and considering this point that about 10-20% of the population can be hypersensitive to nickel, further studies are needed to evaluate the effects of radiofrequency electromagnetic fields (RF-EMFs) emitted from common devices such as mobile phones or Wi-Fi routers on the level of nickel release from orthodontic brackets.

Evaluation of irradiation effects of near-infrared free-electron-laser of silver alloy for dental application.

In the application of lasers in dentistry, there is a delicate balance between the benefits gained from laser treatment and the heat-related damage arising from laser irradiation. Hence, it is necessary to understand the different processes associated with the irradiation of lasers on dental materials. To obtain insight for the development of a safe and general-purpose laser for dentistry, the present study examines the physical effects associated with the irradiation of a near-infrared free-electron laser (FEL) on the surface of a commonly used silver dental alloy. The irradiation experiments using a 2900-nm FEL confirmed the formation of a pit in the dental alloy. The pit was formed with one macro-pulse of FEL irradiation, therefore, suggesting the possibility of efficient material processing with an FEL. Additionally, there was only a slight increase in the silver alloy temperature (less than 0.9 °C) despite the long duration of FEL irradiation, thus inferring that fixed prostheses in the oral cavity can be processed by FEL without thermal damage to the surrounding tissue. These results indicate that dental hard tissues and dental materials in the oral cavity can be safely and efficiently processed by the irradiation of a laser, which has the high repetition rate of a femtosecond laser pulse with a wavelength around 2900 nm.

Laser-treated stainless steel mini-screw implants: 3D surface roughness, bone-implant contact, and fracture resistance analysis.

BACKGROUND/OBJECTIVES: This study investigated the biomechanical properties and bone-implant intersurface response of machined and laser surface-treated stainless steel (SS) mini-screw implants (MSIs). MATERIAL AND METHODS: Forty-eight 1.3mm in diameter and 6mm long SS MSIs were divided into two groups. The control (machined surface) group received no surface treatment; the laser-treated group received Nd-YAG laser surface treatment. Half in each group was used for examining surface roughness (Sa and Sq), surface texture, and facture resistance. The remaining MSIs were placed in the maxilla of six skeletally mature male beagle dogs in a randomized split-mouth design. A pair with the same surface treatment was placed on the same side and immediately loaded with 200 g nickel-titanium coil springs for 8 weeks. After killing, the bone-implant contact (BIC) for each MSI was calculated using micro computed tomography. Analysis of variance model and two-sample t test were used for statistical analysis with a significance level of P <0.05. RESULTS: The mean values of Sa and Sq were significantly higher in the laser-treated group compared with the machined group (P <0.05). There were no significant differences in fracture resistance and BIC between the two groups. LIMITATION: animal study CONCLUSIONS/IMPLICATIONS: Laser treatment increased surface roughness without compromising fracture resistance. Despite increasing surface roughness, laser treatment did not improve BIC. Overall, it appears that medical grade SS has the potential to be substituted for titanium alloy MSIs.

Effect of UV Photofunctionalization on Biologic and Anchoring Capability of Orthodontic Miniscrews.

PURPOSE: Treatment of titanium with UV light immediately before use, or photofunctionalization, is gaining traction as a simple method to improve the biologic capability and clinical performance of dental implants. The objective of this study was to examine the effect of photofunctionalization on the biologic capability and mechanical anchorage of orthodontic miniscrews. MATERIALS AND METHODS: Untreated and photofunctionalized Ti-6Al-4V orthodontic miniscrews were placed into rat femurs. Photofunctionalization was performed by treating miniscrews with UV light for 12 minutes using a photo device immediately before placement. After 3 weeks of healing, miniscrews were pushed laterally to measure the resistance against the tipping force. The miniscrews were also evaluated for morphology and chemistry of tissue formed around them using scanning electron microscopy and energy dispersive spectroscopy. Rat bone marrow-derived osteoblasts were cultured on Ti-6Al-4V disks with and without photofunctionalization. The number of osteoblasts attached to the disks and the behaviors, alkaline phosphatase activity, and mineralization capability of osteoblasts were evaluated. RESULTS: Photofunctionalization converted both disk and screw surfaces from hydrophobic to superhydrophilic. In vivo biomechanical testing showed that the displacement of untreated screws was 1.5 to 1.7 times greater than that of photofunctionalized screws when subjected to lateral tipping force. Robust bone formation was observed around photofunctionalized miniscrews with strong elemental peaks of calcium and phosphorus, whereas the tissue around untreated miniscrews appeared thin and showed no clear peak of calcium. The attachment, initial spreading, adhesion, and expression of functional phenotypes of osteoblasts were significantly increased on photofunctionalized Ti-6Al-4V disks. CONCLUSION: These in vivo and in vitro results comprehensively and consistently demonstrate that photofunctionalization increases the bioactivity of Ti-6Al-4V and improves the anchoring capability of orthodontic miniscrews.

Ultraviolet photofunctionalization increases removal torque values and horizontal stability of orthodontic miniscrews.

INTRODUCTION: The objective of this study was to examine the effects of ultraviolet-mediated photofunctionalization of miniscrews and the in-vivo potential of bone-miniscrew integration. METHODS: Self-drilling orthodontic miniscrews made from a titanium alloy were placed in rat femurs. Photofunctionalization was performed by treating the miniscrews with ultraviolet light for 12 minutes with a photo device immediately before implantation. Maximum insertion torque (week 0), removal torque (weeks 0 and 3), and resistance to lateral tipping force (week 3) were examined. RESULTS: The removal torque at 3 weeks of healing was higher for the photofunctionalized screws than for the untreated screws. The regenerated bone tissue was more intact and contiguous around the photofunctionalized miniscrews than around the untreated ones. The miniscrew-bone complex seemed to produce interface failure, not cohesive fracture, in both groups. The displacement of untreated screws under a lateral tipping force was greater than that of photofunctionalized miniscrews. CONCLUSIONS: These results suggest that photofunctionalization increases the bioactivity of titanium-alloy miniscrews and improves the anchoring capability of orthodontic miniscrews, even without modification of the surface topography.

Effect of mobile phone use on metal ion release from fixed orthodontic appliances.

INTRODUCTION: The aim of this study was to evaluate the effect of exposure to radiofrequency electromagnetic fields emitted by mobile phones on the level of nickel in saliva. METHODS: Fifty healthy patients with fixed orthodontic appliances were asked not to use their cell phones for a week, and their saliva samples were taken at the end of the week (control group). The patients recorded their time of mobile phone usage during the next week and returned for a second saliva collection (experimental group). Samples at both times were taken between 8:00 and 10:00 pm, and the nickel levels were measured. Two-tailed paired-samples t test, linear regression, independent t test, and 1-way analysis of variance were used for data analysis. RESULTS: The 2-tailed paired-samples t test showed significant differences between the levels of nickel in the control and experimental groups (t [49] = 9.967; P <0.001). The linear regression test showed a significant relationship between mobile phone usage time and the nickel release (F [1, 48] = 60.263; P <0.001; R(2) = 0.577). CONCLUSIONS: Mobile phone usage has a time-dependent influence on the concentration of nickel in the saliva of patients with orthodontic appliances.

Removal of filling materials from oval-shaped canals using laser irradiation: a micro-computed tomographic study.

INTRODUCTION: The aim of this study was to assess the efficacy of lasers in removing filling remnants from oval-shaped canals after retreatment procedures with rotary instruments using micro-computed tomographic imaging. METHODS: The root canals of 42 mandibular canines were prepared and obturated using the warm vertical compaction technique. Retreatment was performed with rotary instruments, and the specimens were distributed in 3 groups (n = 14) according to the laser device used in a later stage of retreatment procedure: Er:YAG, Er:YAG laser-based photon-induced photoacoustic streaming, and Nd:YAG. The specimens were scanned in a micro-computed tomographic device after root canal filling and each stage of retreatment at a resolution of 13.68 µm. The percentage differences of the remaining filling material before and after laser application within and between groups were statistically compared using the paired sample t test and 1-way analysis of variance test, respectively. Significance level was set at 5%. RESULTS: Overall, filling residues were located mainly in the apical third and into canal irregularities after the retreatment procedures. After using rotary instruments, the mean percentage volume of the filling remnants ranged from 13%-16%, with no statistical significant difference between groups (P > .05). Within groups, additional laser application had a significant reduction in the amount of the remaining filling materials (P < .05). A comparison between groups showed that Er:YAG laser application after the use of rotary instruments had a significantly higher removal of filling remnants (~13%) than Er:YAG laser-based photon-induced photoacoustic streaming (~4%) and Nd:YAG (~3%) (P < .05). CONCLUSIONS: None of the retreatment procedures completely removed the filling materials. The additional use of lasers improved the removal of filling material after the retreatment procedure with rotary instruments.

Effect of orthodontic brackets and different wires on radiofrequency heating and magnetic field interactions during 3-T MRI.

OBJECTIVES: To evaluate the heating and magnetic field interactions of fixed orthodontic appliances with different wires and ligaments in a 3-T MRI environment and to estimate the safety of these orthodontic materials. METHODS: 40 non-carious extracted human maxillary teeth were embedded in polyvinyl chloride boxes, and orthodontic brackets were bonded. Nickel-titanium and stainless steel arch wires, and elastic and stainless steel ligaments were used to obtain four experimental groups in total. Specimens were evaluated at 3 T for radiofrequency heating and magnetic field interactions. Radiofrequency heating was evaluated by placing specimens in a cylindrical plastic container filled with isotonic solution and measuring changes in temperature after T1 weighted axial sequencing and after completion of all sequences. Translational attraction and torque values of specimens were also evaluated. One-way ANOVA test was used to compare continuous variables of temperature change. Significance was set at p < 0.05. RESULTS: None of the groups exhibited excessive heating (highest temperature change: <3.04 °C), with the maximum increase in temperature observed at the end of the T1 weighted axial sequence. Magnetic field interactions changed depending on the material used. Although the brackets presented minor interactions that would not cause movement in situ, nickel-titanium and stainless steel wires presented great interactions that may pose a risk for the patient. CONCLUSIONS: The temperature changes of the specimens were considered to be within acceptable ranges. With regard to magnetic field interactions, brackets can be considered "MR safe"; however, it would be safe to replace the wires before MRI.

Magnetic displacement force and torque on dental keepers in the static magnetic field of an MR scanner.

PURPOSE: To evaluate the effect of the static magnetic field of magnetic resonance (MR) scanners on keepers (ie, ferromagnetic stainless steel plate adhered to the abutment tooth of dental magnetic attachments). MATERIALS AND METHODS: Magnetically induced displacement force and torque on keepers were measured using 1.5 Tesla (T) and 3.0 T MR scanners and a method outlined by American Society for Testing and Materials (ASTM). Changes in magnetic flux density before and after exposure to scanner static magnetic field were examined. RESULTS: The maximum magnetically induced displacement forces were calculated to be 10.3 × 10(-2) N at 1.5 T and 13.9 × 10(-2) N at 3.0 T on the cover surface. The maximum torques exerted on the keeper (4 mm in diameter) were 0.83 N × 4 mm at 1.5 T and 0.85 N × 4 mm at 3.0 T. These forces were considerably higher than the gravitational force (7.7 × 10(-4) N) of the keeper but considerably lower than the keeper-root cap proper adhesive force. The keepers' magnetic flux density remained less than that of the Earth. CONCLUSION: Magnetically induced displacement force and torque on the keeper in the MR scanner do not influence the keeper-root cap proper adhesive force.

Effects of ultraviolet irradiation on the bond strength of a composite resin adhered to stainless steel crowns.

PURPOSE: A technique whereby the practitioner could improve the esthetic appearance of anterior stainless steel crowns (SSC) could provide a cost-effective alternative to more expensive commercially available preveneered SSCs, which may not be uniformly available. The purpose of this study was to evaluate the effects of ultraviolet (UV) irradiation of the metal crown surface on the shear bond strength of composite resin adhered to stainless steel crowns. METHODS: Seventy extracted anterior bovine teeth randomly divided into 2 groups (n=35/group), were restored with primary maxillary left central incisor SSCs. Surface roughening with a green stone was performed on the labial surfaces, and the crowns of the experimental group were exposed to UV irradiation for 80 minutes. All samples were treated with metal-composite adhesive, followed by composite opaquer. Standardized composite blocks were bonded on the treated surfaces, and the shear bond strength was tested at 1 mm/minute. The values were recorded in MPa and statistically analyzed. RESULTS: The mean value of shear bond strength was significantly higher for the experimental group (19.7 ± 4.3 MPa) than the control group (16.3 ± 4.5 MPa). CONCLUSION: Ultraviolet irradiation of primary tooth stainless steel crowns significantly increased the shear bond strength of composite resin adhered to the facial surface.

Metal artifacts from posterior mandibular implants as seen in CBCT.

PURPOSE: Metal artifacts from dental implants have not been clarified in cone-beam computed tomography (CBCT) images in previous studies. Hence, only mesiodistal metal artifacts from dental implants in the posterior mandibular region were assessed using CBCT. MATERIALS AND METHODS: Twenty-two patients with a total of 61 dental implants in posterior mandibular sites were enrolled. The pixel values surrounding dental implants were measured using CBCT and rotational panoramic radiography, and then the means were calculated. RESULTS: The mean pixel values between dental implants, between dental implants and neighboring teeth, and posterior to dental implants were significantly lower than between neighboring teeth in CBCT. In addition, the mean pixel value between dental implants did not significantly differ from that between neighboring teeth in rotational panoramic radiography. CONCLUSIONS: It was concluded that mesiodistal metal artifacts surrounding dental implants are demonstrated on CBCT.

Biomedical Ti-Mo alloys with surface machined and modified by laser beam: biomechanical, histological, and histometric analysis in rabbits.

PURPOSE: In vivo bone response was assessed by removal torque, hystological and histometrical analysis on a recently developed biomedical Ti-15Mo alloy, after surface modification by laser beam irradiation, installed in the tibia of rabbits. MATERIALS AND METHODS: A total of 32 wide cylindrical Ti-15Mo dental implants were obtained (10mm × 3.75mm). The implants were divided into two groups: 1) control samples (Machined surface - MS) and 2) implants with their surface modified by Laser beam-irradiation (Test samples - LS). Six implants of each surface were used for removal torque test and 10 of each surface for histological and histometrical analysis. The implants were placed in the tibial metaphyses of rabbits. RESULTS: Average removal torque was 51.5Ncm to MS and >90Ncm to LS. Bone-to-implant-contact percentage was significantly higher for LS implants both in the cortical and marrow regions. CONCLUSIONS: The present study demonstrated that laser treated Ti-15Mo alloys are promising materials for biomedical application.

Effects of Er:YAG laser treatments on surface roughness of base metal alloys.

We investigated the effects of different Er:YAG laser treatments on the surface roughness of base metal alloys. A total of 36 specimens were prepared of two base metal alloys (Wiron 99, Bellabond plus). The surfaces of the specimens were standardized by gradual wet grinding with 320-, 600-, 800- and 1,000-grit silicon carbide paper for 10 s each on a grinding machine at 300 rpm. Specimens of each alloy were randomly divided into six groups (n = 6) comprising a control group (group C), a group sandblasted with Al(2)O(3) powder at 60 psi for 10 s through a nozzle at a distance of 10 mm (group S), and four Er:YAG laser (Fotona AT) treatment groups. The laser treatment groups were as follows: 500 mJ, 10 Hz, 100 µs (group 500MSP); 500 mJ, 10 Hz, 300 µs (group 500SP); 400 mJ, 10 Hz, 100 µs (group 400MSP); and 400 mJ, 10 Hz, 300 µs (group 400SP). Surface roughness measurements (Ra) were performed using a profilometer. The data were analysed by two-way ANOVA, and mean values were compared using Tukey's HSD test (α = 0.05). According to the two-way ANOVA results, the base metal alloys and interaction between base metal alloy and surface treatment were not statistically significant different (p > 0.05), the surface treatments were significantly different (p < 0.0001). For the two base metal alloy groups, no significant differences were observed among the control, 400MSP, and 400SP groups (p = 0.912), and these groups demonstrated the lowest Ra values. The highest Ra value was observed in group S (p < 0.05). Er:YAG laser treatment at 400 and 500 mJ/10 Hz is not an alternative method for surface roughening of base metal alloys.

The change of electric potentials in the oral cavity after application of extremely low frequency pulsed magnetic field.

Electric potentials occurring in the oral cavity deserve attention as they may cause various diseases and subjective feelings, which are very difficult to treat. The aim of this study was to evaluate the electric potentials within the oral cavity in patients with metal fillings and metal prosthetic restorations, after using a pulsed electromagnetic field. The study was carried out on 84 patients. The Viofor JPS Classic device was used in the treatment. It generates a pulsed electromagnetic field with low induction of the extremely low frequency (ELF) range. Average values of electric potentials in the preliminary test were about the same in both groups; they were 148.8 mV and 145.5 mV. After another appliance of ELF fields there was found a steady decline in the average value of electric potentials in the study group. This decrease was statistically highly significant, while mean values of electric potentials in the control group were characterized by a slightly upward tendency. The obtained statistically significant reduction of electric potentials in the oral cavity of patients having metal fillings and metal prosthetic restorations, after application of the Viofor JPS Classic device, implies a huge impact of ELF pulsed electromagnetic field on inhibition of electrochemical processes, as well as on inhibition of dental alloy corrosion. 

Accelerated photo-induced hydrophilicity promotes osseointegration: an animal study.

BACKGROUND: In the previous in vitro study, fluoride-modified, anodized porous titanium was proven to have enhanced its photo-induced hydrophilicity, which induced the hyperactivation of initial cell response. PURPOSE: The purpose of the present study was to investigate in vivo bone apposition during the early stages of osseointegration in rabbit tibiae. MATERIALS AND METHODS: Anodized porous titanium implants (TiU, TiUnite®, Nobel Biocare AB, Göteborg, Sweden) were modified with 0.175 wt% ammonium hydrogen fluoride solution (NH(4) F-HF(2) ). Twenty-four hours prior to the experiments, the surface-modified implants were ultraviolet-irradiated (modTiU). Blinded and unpackaged TiU implants were used as controls. Thereafter, the implants were placed in the rabbit tibial metaphyses and histomorphometrically analyzed at 2 and 6 weeks after insertion. RESULTS: ModTiU demonstrated a significantly greater degree of bone-to-metal contact than TiU after 2 and 6 weeks of healing. CONCLUSION: The results proved that the enhanced photo-induced hydrophilicity of the NH(4) F-HF(2) -modified anodized implants promoted bone apposition during the early stages of osseointegration.

Effect of Er:YAG, CO(2) and diode laser irradiation on surface properties of zirconia endosseous dental implants.

BACKGROUND AND OBJECTIVES: Zirconia implants (ZI) are becoming more popular in implant dentistry, as a result of their favorable esthetic outcome. However, little is known about the impact laser application has on this material in the course of peri-implantitis treatment. The objective of this investigation was to analyze the influence of Er:YAG, CO(2) and diode laser irradiation on polished ZI. MATERIAL AND METHODS: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic disks were irradiated at different power settings with either an Er:YAG, CO(2) or diode laser. The surface of the disks was analyzed by scanning electron microscopy (SEM) and confocal 3D white light microscopy (CWLM). In addition energy-dispersive X-ray (EDX) analysis was performed on all disks. Six specimens were used for each parameter set of each laser. RESULTS: SEM analysis demonstrated that, regardless of the power settings, neither the diode laser nor the Er:YAG laser caused any visible surface alterations to ZI. The results of the CWLM were in agreement with the SEM pictures. However, Er:YAG irradiation did penetrate through the disks. At various power settings, the CO(2) treatment was characterized by material cracking and melting. The increased roughness values (from CWLM) of the ZI underlined the SEM observations. CONCLUSION: In contrast to diode and Er:YAG laser irradiation, the CO(2) laser revealed distinct surface alterations to zirconia at various laser parameters. However, the Er:YAG laser cannot be recommended for the treatment of ailing implants, as the laser beam penetrates the material. In this respect, currently, diode lasers seem to be the only laser systems offering surface preservation and safety in the treatment of peri-implantits with ZI.

Effect of welding parameters on penetration of Nd:YAG laser into cast Ti and Au- and Ag-based alloys.

OBJECTIVE: The objective of this study was to investigate the effect of laser welding parameters (current [A], spot diameter [mm], and pulse duration [ms]) on the weld penetration depth by Nd:YAG laser into cast titanium and Ag-based and Au-based alloys. METHOD AND MATERIALS: Two cast blocks of each metal were laser welded with various parameters at their interface. The blocks were then separated, and the penetration depth into each metal was measured on the separated surface using a computer program. The data were statistically analyzed. RESULTS: Increasing the current and decreasing the spot diameter increased the penetration depth into each alloy. No statistical differences in penetration depth were found for each metal among the pulse durations. CONCLUSION: The results suggested that, regardless of the pulse duration, the current and the spot diameter in relation to the power density (W/cm2) of the laser affected the weld penetration depth into each metal. Cast titanium produced more penetration depth compared to gold alloys because of its low thermal conductivity value and high rate of laser beam absorption.

Laser welding of cast titanium and dental alloys using argon shielding.

PURPOSE: This study investigated the effect of argon gas shielding on the strengths of laser-welded cast Ti and Ti-6Al-7Nb and compared the results to those of two dental casting alloys. MATERIALS AND METHODS: Cast plates of Ti, Ti-6Al-7Nb, gold, and Co-Cr alloy were prepared. After polishing the surfaces to be welded, two plates were abutted and welded using Nd:YAG laser at a pulse duration of 10 ms, spot diameter of 1 mm, and voltage of 200 V. Five specimens were prepared for each metal by bilaterally welding them with three or five spots either with or without argon shielding. The failure load and percent elongation were measured at a crosshead speed of 1.0 mm/min. RESULTS: The factor of argon shielding significantly affected the failure load and elongation of the laser-welded specimens. The failure loads of argon-shielded laser-welded CP Ti and Ti-6Al-7Nb were greater compared with the failure loads of specimens welded without argon shielding for both three- and five-spot welding. Regardless of argon shielding, the failure loads of the laser-welded gold alloy were approximately half that of the control specimens. In contrast, the failure loads of the nonshielded laser-welded Co-Cr alloy were greater. The percent elongations positively correlated with the failure loads. CONCLUSIONS: The use of argon shielding is necessary for effective laser-welding of CP Ti and Ti-6Al-7Nb but not for gold and Co-Cr alloy.

Influence of electron beam irradiation on the alloy-to-resin bond strength.

The aim of this study was to investigate whether postcuring using electron beam irradiation had an effect on the bond strength of resin-to-base-metal after priming their surfaces using silicoating methods or functional monomers. Composite cylinders were bonded on a restricted area of 5 mm2 to flat rectangular titanium and cobalt-chromium specimens. Under investigation were the silicoating system Rocatec, the thiol-phosphate system Metal Primer II and the phosphate ester SR Link. Tensile strength and shear bond strength were determined for the three test groups in each case: (i) after 24 h, (ii) after electron beam irradiation (100 kGy), and (iii) after irradiation (100 kGy) + 12,000 cycles of thermal cycling (5 degrees /55 degrees C). The bond strength was highly affected by irradiation and the metal priming method used. However, the tribochemical silicoating method and phosphate-ester group showed no significant statistical change in bond strength. Only the thiol-phosphate system showed considerably higher tensile and shear bond strengths after irradiation. Thermal cycling did not deteriorate this bond and there was a tendency for higher bond strength on titanium. As a result it was determined that thiol-phosphate primers in combination with postcuring using electron beam irradiation can considerably improve the bond strength between resins and titanium or cobalt-chromium alloys.

In vivo dose perturbation effects of metallic dental alloys during head and neck irradiation with intensity modulated radiation therapy.

A patient with base of tongue squamous sell carcinoma, with significant CT artifact-inducing metallic alloy, non-removable dental restorations in both the mandible and maxilla was identified. Simultaneous with IMRT treatment, thermoluminescent dosimeters (TLDs) were placed in the oral cavity. After a series of three treatments, the data from the TLDs and software calculations were analyzed. Analysis of mean in vivo TLD dosimetry reveals differentials from software predicted dose calculation that fall within acceptable dose variation limits. IMRT dose calculation software is a relatively accurate predictor of dose attenuation and augmentation due to dental alloys within the treatment volume, as measured by intra-oral thermoluminescent dosimetry. IMRT represents a safe and effective methodology to treat patients with non-removable metallic dental work who have head and neck cancer.