Efficacy of low-intensity laser therapy in reducing treatment time and orthodontic pain: a clinical investigation.

INTRODUCTION: The long duration of orthodontic treatment is a major concern for patients. A noninvasive method of accelerating tooth movement in a physiologic manner is needed. The aim of this study was to evaluate of the efficacy of low-intensity laser therapy in reducing orthodontic treatment duration and pain. METHODS: Twenty patients requiring extraction of first premolars were selected for this study. We used a randomly assigned incomplete block split-mouth design. Individual canine retraction by a nickel-titanium closed-coil spring was studied. The experimental side received infrared radiation from a semiconductor (aluminium gallium arsenide) diode laser with a wavelength of 810 nm. The laser regimen was applied on days 0, 3, 7, and 14 in the first month, and thereafter on every 15th day until complete canine retraction was achieved on the experimental side. Tooth movement was measured on progress models. Each patient's pain response was ranked according to a visual analog scale. RESULTS: An average increase of 30% in the rate of tooth movement was observed with the low-intensity laser therapy. Pain scores on the experimental sides were significantly lower compared with the control sides. CONCLUSIONS: Low-intensity laser therapy is a good option to reduce treatment duration and pain.

Survival of turned and roughened dental implants in irradiated head and neck cancer patients: a retrospective analysis.

STATEMENT OF PROBLEM: Dental implants placed into previously radiated fields in survivors of head and neck cancer can demonstrate survival rates that are less than optimal. Understanding this behavior may assist with treatment planning in accordance with expected survival rates in these patients. PURPOSE: The purpose of this study was to compare the survival of implants with turned and roughened surfaces placed in patients who had previously received head and neck radiation, and to identify factors associated with implant failure. MATERIAL AND METHODS: The records of 48 patients who had prior head and neck radiation and had 271 dental implants placed between May 1987 and July 2008 were examined. All of the implants were placed in a previously irradiated field dosed to at least 50 Gy. Implant survival was estimated using the Kaplan-Meier method and univariate Cox models with robust standard errors were fitted to evaluate the association between patient/implant factors and implant failure. RESULTS: There were 62 implants placed in the maxilla (32 roughened, 30 turned) and 209 implants (107 roughened, 102 turned) placed in the mandible. The 5-year implant survival rate for implants placed in the maxilla was 72.6% for turned implants and 87.5% for roughened implants. For implants placed in the mandible, the 5-year survival rate was 91.7% for turned implants and 100% for roughened implants. Among implants with a turned surface, implants were more likely to fail if they were placed in the maxilla (P=.008) and if the diameter was ≤3.75 mm (P=.002). CONCLUSIONS: Implants with turned surfaces were 2.9 times more likely to fail compared to the roughened dental implants, although the difference did not reach statistical significance. For implants with turned surfaces, there was a tendency for implants in the maxilla to fail more frequently compared to the mandible. Implants with turned surfaces had a higher likelihood of failure in the posterior region than in the anterior region. For implants with roughened surface there was no significant association between implant survival and location of the implant, type of bone, or length or diameter of the implant.

Survival of dental implants in native and grafted bone in irradiated head and neck cancer patients: a retrospective analysis.

AIM: To study the long-term survival of dental implants placed in native or grafted bone in irradiated bone in subjects who had received radiation for head and neck cancer. MATERIALS AND METHODS: A retrospective chart review was conducted for all patients who received dental implants following radiation treatment for head and neck cancer between May 1, 1987 and July 1, 2008. Only patients irradiated with a radiation dose of 50 Gy or greater and those who received dental implants in the irradiated field after head and neck radiation were included in the study. The associations between implant survival and patient/implant characteristics were estimated by fitting univariate marginal Cox proportional hazards models. RESULTS: A total of 48 patients who had prior head and neck radiation had 271 dental implants placed during May 1987-July 2008. There was no statistically significant difference between implant failure in native and grafted bone (P=0.76). Survival of implants in grafted bone was 82.3% and 98.1% in maxilla and mandible, respectively, after 3 years. Survival of implants in native bone in maxilla and mandible was 79.8% and 100%, respectively, after 3 years. For implants placed in the native bone, there was a higher likelihood of failure in the maxilla compared to the mandible and there was also a tendency for implants placed in the posterior region to fail compared to those placed in the anterior region. CONCLUSION: There was no significant difference in survival when implants were placed in native or grafted bone in irradiated head and neck cancer patients. For implants placed in native bone, survival was significantly influenced by the location of the implant (maxilla or mandible, anterior or posterior).

Assessment of vascularity in irradiated and nonirradiated maxillary and mandibular minipig alveolar bone using laser doppler flowmetry.

PURPOSE: The purpose of this animal study was to confirm that laser Doppler flowmetry (LDF) is a reproducible method for the assessment of maxillary and mandibular alveolar bone vascularity and that there is less vascularity in irradiated mandibular and maxillary bone compared to nonirradiated bone. MATERIALS AND METHODS: All maxillary and mandibular premolars and molars of 6 Göttingen minipigs were extracted. After a 3-month healing period, 3 minipigs received irradiation at a total dose of 24 Gy. Three months after irradiation, 5 holes were drilled in the residual alveolar ridge of each edentulous site in each minipig. Local microvascular blood flow around all 120 holes was recorded by LDF prior to implant placement. In 1 irradiated and 1 nonirradiated minipig, an additional hole was drilled in a right maxillary site to enable repeated LDF recordings. RESULTS: The alveolar bone appeared less vascularized in irradiated than in nonirradiated minipigs. The effect of radiation appeared more pronounced in the mandible than in the maxilla. LDF was demonstrated to be a reproducible method for assessing alveolar bone vascularity. However, recordings varied by edentulous site as well as by minipig. CONCLUSION: The authors' hypotheses regarding LDF and vascularity were supported. Further research validating the use of LDF in human beings, especially in those who have undergone radiation therapy for head and neck cancer, is necessary.

The effect of prior radiation therapy for treatment of nasopharyngeal cancer on wound healing following extractions: incidence of complications and risk factors.

This is a prospective study of wound healing after extractions in patients who had radiation therapy for nasopharyngeal cancer. From 40 patients who fulfilled all the study criteria were extracted a total of 155 teeth. The demographic data were analysed, checking for factors that might affect the healing process after extraction. Wound healing was divided into three groups: normal wound healing, delayed healing and osteoradionecrosis. Logistic regression was used to analyse possible relationships. There was a low complication rate: 5.8% and 1.9% of extractions showed delayed healing and osteoradionecrosis, respectively. The age of the patient at time of extraction was the only significant factor that influenced the occurrence of delayed healing. It was observed that localized radiation absorption was considerably different from the total radiation dose. In conclusion, postradiation extractions have a low risk of complications and the results point to age as a factor that may influence wound healing.

Paediatric absorbed doses from rotational panoramic radiography.

OBJECTIVES: To determine the paediatric doses in rotational panoramic radiography with film/screen and photostimulable phosphor receptors. STUDY DESIGN: A paediatric anthropomorphic head and neck phantom was used. Absorbed doses were measured for two panoramic systems, the Orthophos (Sirona Dental Systems, Bensheim, Germany) and the PM 2002 CC (Planmeca Oy, Helsinki, Finland), with and without programmable child settings, using both screen/film and photostimulable phosphor receptors. RESULTS: Absorbed doses to the eye ranged from 5 to 24 micro Gy. Doses to the dental arches with the Orthophos unit ranged from 50 to 555 micro Gy with the adult and from 27 to 436 micro Gy with the child program; using the PM 2002 CC unit, doses ranged from 56 to 1040 micro Gy using the adult settings, and from 60 to 890 micro Gy with the paediatric settings. The paediatric exposure settings reduced doses at most locations for both panoramic systems. The highest doses were measured near the rotational axes of the X-ray beam. Paediatric settings with the Orthophos P10 resulted in the dose reduction more than 50% to the thyroid but not with the PM 2002 CC. When lower kVcp or mA settings were used, absorbed doses were effectively reduced for all combinations of machines, programs and detectors. CONCLUSIONS: Specific program settings for children reduced the absorbed doses from panoramic radiography irrespective of the machine or receptor used.

Mandibular endosseous implants and autogenous bone grafting in irradiated tissue: a 10-year retrospective study.

Nineteen patients received tumoricidal doses of radiation and subsequently underwent mandibular endosseous implant reconstruction, followed by dental rehabilitation with complete arch fixed osseoprostheses. Eight of the 19 patients also underwent autogenous bone graft reconstruction for mandibular discontinuity. A surgical and prosthetic protocol for irradiated head and neck oncology patients is presented. The 10-year retrospective study of 19 consecutively treated patients revealed an endosseous implant survival of 99%, dental osseoprosthesis continuous service of 100%, and successful bone graft reconstruction of 89%.

Histologic changes in dental morphology induced by high dose chemotherapy and total body irradiation.

Disturbances in dental development were studied with the use of radiography and histology in a patient with acute lymphoblastic leukemia who was treated with induction chemotherapy at 2.3 years of age and bone marrow transplantation at 4.3 years of age. The follow-up 9.5 years after bone marrow transplantation showed evidence of short tapered roots, enamel hypoplasia, microdontia, and aplasia. A histologic examination of two extracted permanent teeth showed that the crown of the maxillary lateral incisor exhibited numerous incremental lines that corresponded closely to the treatment periods with cytotoxic drugs. The maxillary second premolar exhibited regularly spaced incremental lines in the enamel and dentine. A gross hypoplasia was seen in the cervical part of the crown corresponding to the time of administration of 10 Gy total body irradiation. The results indicate that chemotherapy mainly induces qualitative disturbances in dentine and enamel, whereas total body irradiation induces both qualitative and quantitative changes.

The effect of low-level laser treatment on maxillary arch dimensions after palatal surgery on beagle dogs.

The effect of low-level laser treatment on maxillary arch dimensions after palatal surgery was investigated in Beagle dogs at an age of 12 weeks. A total of 30 dogs was used, and they were assigned to either a control group (Group C, n = 6) or one of two experimental groups (Group L, n = 12; and group LL, n = 12). After Von Langenbeck's palatal repair in the two experimental groups, denuded bony areas in the LL group were irradiated with a continuous Ga-As-Al laser beam (830 nm) and energy output set at 30 mW. A dosage of 1 J/cm2 wound surface area was used. Treatment was carried out three times a week, with a total of ten treatments. The animals of the L group served as non-treated control animals. Dental casts were made of all animals of all groups at regular intervals until they reached 25 weeks of age. Maxillary arch dimensions were studied. Dental arch dimensions in the deciduous dentition of both experimental groups were not disturbed by surgery, but after eruption of permanent teeth, mainly transverse maxillary arch dimensions in the premolar region increased less in both experimental groups than in the control group. It was concluded that low-level laser treatment under the conditions used in this study did not decrease the adverse iatrogenic effects of palatal surgery on maxillary arch dimensions.