Alveolus soft and bone tissue regeneration after laser biomodulation - a histological study.

Functional and esthetic recovery of the patient after tooth extraction is a concern in the nowadays-dental medicine. Immediate implant placement in fresh sockets in posterior sides of the jaws is difficult because of the high amount of bone loss and the disparity between the diameter of the alveolus and the implant. The objective is to evaluate the effect of laser biomodulation alveolar socket healing process of healthy patients. A number of 36 molars have been extracted due to advanced caries lesions from the same dental arch but on opposite sites. Laser irradiation was performed on one side after extraction; the other side was used as control. An Epic-X laser diode (Biolase) Indium-Gallium-Arsenide-Phosphorus (In-Ga-As-P) 940 nm was used in a continuous mode, 0.9 W, 36 J for 80 seconds, daily exposure, in the first seven days after extraction. Specimens of soft and hard tissue were surgically incised and removed by a 4.4 mm diameter trepan from the extraction sites, eight weeks after the surgical procedure. The specimens were prepared by use of two staining procedures: Hematoxylin-Eosin (HE) and Mallory's trichrome. The prepared slides were examined under Leica DM750 optical microscope, 5× and 10× magnification. Laser biomodulation therapy accelerates bone formation by increasing osteoblastic activity. The histological study demonstrates early new bone formation, the regeneration effects in fresh intact bony alveolus compared with the soft and bone regeneration level of non-treated fresh alveolus. Laser biomodulation therapy accelerates soft tissue regeneration and bone formation.

Low-intensity pulsed ultrasound promotes alveolar bone regeneration in a periodontal injury model.

Periodontitis is a common oral disease characterized by progressive destruction of periodontal tissue and loss of teeth. However, regeneration of periodontal tissue is a time-consuming process. Low-intensity pulsed ultrasound (LIPUS) is a widely used non-invasive intervention for enhancing bone healing in fractures and non-unions. With the hypothesis that LIPUS may accelerate periodontal regeneration, the effects of LIPUS on periodontal tissue regeneration were investigated both in vitro and in vivo. LIPUS (90 mw/cm2, 20 min/d, 1.5 MHz) was applied to stimulate dog periodontal ligament cells (dPDLCS). The mRNA expression of BSP (P < 0.05), OPN (P < 0.05) and COL3 (P < 0.05) was increased significantly in the LIPUS group. The positive stained mineralized nodules by alizarin red in the LIPUS group were greater than in the control group (P < 0.05). Eight male beagle dogs were divided into 4 groups: guided tissue regeneration (GTR) group (G1), LIPUS + GTR group (G2), LIPUS group (G3), and control group (G4, no treatment). A 4 × 5 mm2 defect was created in the buccal alveolar bone. The modeling areas in the G2 and G3 groups were then exposed to LIPUS. Eight weeks after surgery, histological assessment indicated increased periodontal tissue in the LIPUS + GTR group. Micro computed tomography (micro-CT) showed that the regenerated bone volume (BV) in the G2 was significantly higher than that in the G1, G3 and G4 groups (P < 0.05). The bone surface (BS) trabecular number (Tb.N) and trabecular thickness (Tb.Th) in G2 were markedly higher than in G4 (P < 0.05). It is concluded that LIPUS + GTR can accelerate new alveolar bone formation, with a prospective for promoting periodontal tissue repair.

Comparative evaluation of various low-level laser therapies on bone healing following tooth extraction: An experimental animal study.

PURPOSE: The aim of this study was to evaluate the effects of helium-neon and gallium-aluminum-arsenide lasers with various doses on bone healing following tooth extraction. MATERIALS AND METHODS: Maxillary right incisor teeth of 30 female albino Wistar rats were extracted. Five groups were established: four groups treated with helium-neon or gallium-aluminum-arsenide lasers and a control group. Both laser groups' rats received energy doses of 6 J/cm2 and 10 J/cm2 for 7 days. At the end of 30 days, all subjects were sacrificed for histological and morphological evaluations. RESULTS: Laser groups showed faster bone healing and gallium-aluminum-arsenide lasers increased vascular immunoreactivity. The most widespread organized bone formation in the extraction socket was observed in the gallium-aluminum-arsenide laser group with the energy dose of 10 J/cm2 (p < 0.05). CONCLUSION: This study demonstrated that low-level laser therapies were effective on alveolar bone healing and that an energy dose of 10 J/cm2 did not have an inhibition effect on bone regeneration.

Alveolar bone remodeling after tooth extraction in irradiated mandible: An experimental study with canine model.

OBJECTIVES: The aim of the present study is to investigate the morphological and cellular changes in dental extraction socket that has been irradiated after the tooth extraction and to describe morphological characteristics of the osteocytes and osteocyte-lacunar-canalicular network (LCN) by scanning electron microscopy (SEM). MATERIAL AND METHODS: Five beagle dogs aged 1-2 years were used in this study. One side of each mandible was irradiated in two sessions and the other side of mandible (non-irradiated) served as a control. The mandible bone blocks were processed by bulk staining en bloc in basic fuchsin and the specimens were embedded routinely in polymethyl methacrylate resin without preliminary decalcification. All blocks were subjected to micro-CT imaging, after that the specimens were prepared for light microscopy and SEM. RESULTS: Alterations in bone macrostructure are minimal in irradiated bone, but the changes in LCN are clear. In the area of the tooth extraction socket, the connections of osteocytes to the vessels and to neighboring osteocytes were not observed both in irradiated and nonirradiated bone. However, osteoclasts were located in the bone surface entering inside to the bone between osteons. In the lamellar bone of lateral sides, a decrease in canalicular connections between osteocytes and periosteum was found in irradiated bone as compared to the non-irradiated side. CONCLUSIONS: The novelty of the present study is that radiation disrupts osteocytes and their dendrites.

Effects of Low-Level Laser Therapy With a Herbal Extract on Alveolar Bone Healing.

PURPOSE: This study investigated the effect of a gallium-aluminum-arsenide (GaAlAs) diode laser used in low-level laser therapy (LLLT) with the application of Mecsina Hemostopper on mandibular alveolar bone healing. MATERIALS AND METHODS: Standard semispherical bone defects were created in left mandibular diastema sites of 32 female Long-Evans rats. Experimental animals were allocated to 1 of 4 groups: control group (no treatment), laser group (GaAlAs LLLT), Mecsina group, and laser-Mecsina combination group. Liquid Mecsina 0.01 mL was applied to the bone defects. Laser treatment was performed for 7 days after surgery at an energy dose of 10 J/cm2. All animals were sacrificed to observe hard tissue healing histologically, immunohistochemically, and radiologically at 30 days after surgery. RESULTS: Histologic assessment showed significantly more calcified tissue areas and significantly more osteoblast cells in the laser and laser-Mecsina groups than in the other groups (P < .01). Qualitative morphologic assessment showed that more bone tissue was present in the laser-Mecsina group than in the other groups. CONCLUSION: This study showed that LLLT, Mecsina application, and combined treatments were effective in healing alveolar bone among all tested treatment modalities.

Low-level laser therapy and invisible removal aligners.

It seems that Low Level Laser Therapy (LLLT) stimulates orthodontic tooth movements, increasing the alveolar bone turnover. The aim of this study is to evaluate how LLLT can influence the orthodontic treatment with invisible removal aligner. A sample of 21 subjects was divided into two groups, a laser group (10 patients) and a control group (11 patients). All subjects were instructed to wear each aligner 12 hours a day for 2 weeks. Laser external bio-stimulation was given in the laser group every second week. The laser group successfully finished the treatment, while at 3rd – 5th aligner the control group did not finish the treatment. Laser treatment seemed to be better than treatment without laser. LLLT combined with aligners is able to favour, in 12 hours, the same tooth movement obtained by wearing the aligner 22 hours a day, according to the traditional protocol. This aspect could be useful for those patients who prefer not to use the aligners during the day. LLLT makes invisible removal aligner treatment more comfortable also because during the day the patients have to wear the aligners less hours than the treatment without laser.

Changes in Peri-Implant Bone Level and Effect of Potential Influential Factors on Dental Implants in Irradiated and Nonirradiated Patients Following Multimodal Therapy Due to Head and Neck Cancer: A Retrospective Study.

PURPOSE: The aim of the present study was to evaluate changes in the marginal bone level of dental implants in irradiated and nonirradiated patients and to identify possible influential factors. MATERIALS AND METHODS: Thirty-six patients with 194 implants were involved in the study (7 women and 29 men). The mean age of the patients was 65.8 years (39 to 90 yr). In all patients, a squamous cell carcinoma in the floor of the mouth involving the mandible or tongue was surgically removed. In 17 patients, adjuvant radiochemotherapy was completed a minimum of 6 months before implant placement. Mean crestal bone changes using standardized orthopantomographs were evaluated. The Spearman rank-order correlation coefficient and Mann-Whitney U test were used to determine correlations between bone crestal changes and age, gender, radiation therapy (yes vs no), augmentation (yes vs no), and type of superstructure. RESULTS: In total, 194 implants were placed (73 in the maxilla and 121 in the mandible). Mean amounts of peri-implant bone loss were 1 mm mesially and 0.9 mm distally after 1 year and 1.4 mm mesially and 1.3 mm distally after 3 years. During the observation period, 4 implants were lost. The overall success rate was 98.4% (maxilla, 100%; mandible, 96.7%). There was no relevant difference in changes in bone level according to age, gender, prosthetic superstructure, or augmentation procedure (yes vs no). Radiation therapy was found to have an effect on crestal bone loss. CONCLUSION: The present study showed a high success rate of dental implants after 3 years. Peri-implant crestal bone loss was comparable to that in patients without tumor. The mean amount of crestal bone change in irradiated patients was twice as high as that in nonirradiated patients.

Energy output reduction and surface alteration of quartz tips following Er:YAG laser contact irradiation on soft and hard tissues in vitro.

Though the Er:YAG laser (ErL) has been used in periodontal therapy, the irradiated tip damage has not been studied in detail. In this study, the change in the energy output, surface morphology, and temperature of quartz tips was evaluated following contact irradiation. Soft tissue, calculus on extracted human teeth, and porcine bone were irradiated by ErL for 60 min at 14.2 or 28.3 J/cm(2)/pulse and 20 Hz with or without water spray. The energy output ratio declined the most in the calculus group, followed by the bone and soft tissue groups with and/or without water spray. Carbon contamination was detected in all groups, and contamination by P, Ca, and/or other inorganic elements was observed in the calculus and bone groups. The rate of energy output reduction and the degree of surface alteration/contamination is variously influenced by the targeting tissue, temperature elevation of the tip and water spray.

The Radiological and Stereological Analysis of the Effect of Low-Level Laser Therapy on the Mandibular Midline Distraction Osteogenesis.

OBJECTIVE: The aim of this study was to evaluate the effect of low level laser therapy (LLLT) on bone mineral density by using high-resolution computerized tomography (HR-CT) and stereology in patients subjected to mandibular midline distraction. METHODS: Nine patients between the ages of 13 and 16 years with mandibular transverse deficiency (>5 mm) were evaluated. Mandibular midline distraction osteogenesis was performed for all the patients. The patients were divided into 2 groups: the control group (n = 4) and the laser group (n = 5). GaAlAs, 830 nm wavelength, power of 40 mW, energy of 8.4 J/cm2 dose per spot, was directly applied from 2 points on the mandibular midline. The laser was applied in 8 treatment sessions at 48-hour intervals. Bone mineral density and volume of the newly formed bone were analyzed using HR-CT and stereological methods. RESULTS: A higher bone mineral density rate was found in the laser group (P < 0.05). A higher newly formed immature bone rate was found in the control group (P < 0.001). These findings suggest that more mature bone may also have a greater mineral organization than that of immature newly formed bone, which is shown by HR-CT and stereological results. CONCLUSIONS: The retention period can be shortened and mineralization may be increased by using LLLT in mandibular distraction osteogenesis.

Effect of low-level laser therapy on orthodontic tooth movement into bone-grafted alveolar defects.

INTRODUCTION: The objective of this study was to investigate the effect of low-level laser therapy (LLLT) on the rate of orthodontic tooth movement (OTM) into bone-grafted alveolar defects based on different healing states. METHODS: Ten male beagles were randomly allocated to 3 groups: group C, OTM alone as a control; group G, OTM into the grafted defects; group GL, OTM into the grafted defects with LLLT. The maxillary second premolars were protracted into the defects for 6 weeks, immediately (G-0 and GL-0) and at 2 weeks (G-2 and GL-2) after surgery. The defects were irradiated with a diode laser (dose, 4.5 J/cm(2)) every other day for 2 weeks. The rates of OTM and alveolar bone apposition, and maturational states of the defects were analyzed by histomorphometry, microcomputed tomography, and histology. RESULTS: The total amounts of OTM and new bone apposition rates were decreased by LLLT, with increased bone mineral density and trabecular maturation in the defects. Group GL-2 had the slowest movement with root resorption in relation to less woven bone in the hypermatured defect. CONCLUSIONS: LLLT significantly decreased the rate of OTM into the bone-grafted surgical defects by accelerating defect healing and maturation, particularly when the start of postoperative OTM was delayed.

Micro-computed tomography and histomorphometric analysis of human alveolar bone repair induced by laser phototherapy: a pilot study.

Immediate dental implant placement in the molar region is critical, because of the high amount of bone loss and the discrepancy between alveolar crest thickness and the implant platform. Laser phototherapy (LPT) improves bone repair. The aim of this study was to evaluate the human alveolar bone repair 40 days after molar extraction in patients submitted to LPT. Twenty patients were selected for this randomized controlled clinical trial; 10 underwent LPT (laser group) with a GaAlAs diode laser (808 nm, 100 mW, 0.04 cm(2), 75 J/cm(2), 30s per point, 3 J per point, at five points). The control group patients (n=10) were not irradiated. Forty days later, the tissue formed inside the sockets was analyzed by micro-computed tomography and histomorphometry. Data from the two groups were compared with Student's t-test and Pearson's correlation test. The relative bone volume was significantly higher in the laser group (P<0.0001). The control group showed negative correlations (P<0.01) between number and thickness, and between number and separation of trabeculae, and a positive correlation between thickness and separation of trabeculae. The laser group showed a significant negative correlation between the number and thickness of trabeculae (P<0.01). The results suggest that LPT is able to accelerate alveolar bone repair after molar extraction, leading to a more homogeneous trabecular configuration represented by thin and close trabeculae.

Time interval after radiotherapy and dental implant failure: systematic review of observational studies and meta-analysis.

BACKGROUND: Typically, dental implants are placed in irradiated bone after a delay that exceeds 6 months, but it is not known whether longer delays are beneficial. PURPOSE: The purpose of the study is to review the literature comparing the failure rate of dental implants placed in irradiated bone between 6 and 12 months and after 12 months from the cessation of radiotherapy. MATERIALS AND METHODS: Four electronic databases were searched for articles published until February 2013 without language restriction: Lilacs, Medline, Scopus, and the Cochrane Central Register of Controlled Trials. Two reviewers independently assessed the eligibility criteria and extracted data. Fixed effect meta-analysis was performed. RESULTS: Overall, 3,749 observational studies were identified. After the screening of titles and abstracts, 236 publications were selected, and 10 were included in the final analysis. The pooled relative risk (RR) of failure was RRpooled = 1.34 (95% confidence interval [CI]: 1.01-1.79), higher in individuals who had dental implants installed between 6 and 12 months after receiving radiotherapy. I(2) indicated nearly 21% heterogeneity (p = .25). Egger's test indicated no evidence of publication bias (p = .62); however, the removal of one study significantly affected the overall RR (RRpooled = 1.08, 95% CI: 0.77-1.52). CONCLUSIONS: Placing implants in bone within a period shorter than 12 months after radiotherapy may result in a higher risk of failure; however, additional evidence from clinical trials is needed to verify this risk.

Impact of extracorporeal shock-wave therapy on the stability of temporary anchorage devices in adults: a single-center, randomized, placebo-controlled clinical trial.

INTRODUCTION: In this randomized, placebo-controlled clinical trial, we investigated the effect of noninvasive extracorporeal shock waves on the stability of temporary anchorage devices (TADs) under orthodontic loading. METHODS: Thirty adult orthodontic patients of the Bernhard Gottlieb University Clinic in Vienna, Austria, were enrolled in this clinical trial and allocated by block randomization (size, 4) in a 1:1 ratio to either the treatment or the placebo group. Randomization was performed with software, and the allocations were concealed in sealed envelopes. Eligibility criteria included healthy adult patients with mesially directed orthodontic movement of the mandibular second molar into the extraction site of the mandibular first molar. The fixed orthodontic devices included active superelastic coil springs (200 cN) and TADs in the mandibular alveolar bone. Blinding was performed for the subjects and the outcome assessor. The treatment group received 1 shock-wave application with 1000 impulses at 0.19 to 0.23 mJ per square millimeter in the region of the TADs. The placebo group was treated with a deactivated shock-wave applicator and acoustic sham. The TADs positions were evaluated at placement and after 4 months. The reliability and precision of the impression process of the TADs were evaluated in an in-vitro model. RESULTS: Thirteen participants finished the investigation successfully in the treatment group but only 12 finished in the placebo group because 1 TAD loosened. The difference of the total TAD displacement for the 4-month time period between the placebo and treatment groups was 0.17 ± 0.95 mm (95% CI: -0.96, 0.62). No statistically significant difference between the 2 groups was found when sex was evaluated. Primary stability of the TADs as measured by placement torque, amount of tooth movement, and age of the patients did not influence displacement of the TADs. The reliability and precision of TAD impressions were confirmed. No unintended pernicious effects occurred after shock-wave treatment during the study period. CONCLUSIONS: A single application of extracorporeal shock-wave treatment did not improve the stability of the TADs during orthodontic loading. Sufficient interradicular space should be provided to minimize the risk of periodontal and dental root defects. REGISTRATION: This trial was registered at https://clinicaltrials.gov. PROTOCOL: The protocol was published before trial commencement, NCT01695928. FUNDING: No funding or conflict of interest to be declared.

Histological analysis of the periodontal ligament and alveolar bone during dental movement in diabetic rats subjected to low-level laser therapy.

OBJECTIVE: The purpose of this research was to evaluate the histological changes of the periodontal ligament and alveolar bone during dental movement in diabetic rats subjected to low level laser therapy (LLLT). METHODS: The movement of the upper molar was performed in 60 male Wistar rats divided into four groups (n=15): CTR (control), DBT (diabetic), CTR/LT (irradiated control) and DBT/LT (irradiated diabetic). Diabetes was induced with alloxan (150 mg/kg, i.p.). LLLT was applied with GaAlAs laser at 780 nm (35 J/cm(2)). After 7, 13 and 19 days, the periodontal ligament and alveolar bone were histologically analyzed. RESULTS: The mean of osteoblasts (p<0.01) and blood vessels (p<0.05) were significantly decreased in DBT compared with CTR at 7 days, whereas the mean of osteoclasts was lower at 7 (p<0.001) and 13 days (p<0.05). In DBT/LT, only the mean of osteoclasts was lower than in CTR (p<0.05) at 7 days, but no difference was observed at 13 and 19 days (p>0.05). The collagenization of the periodontal ligament was impaired in DBT, whereas DBT/LLT showed density/disposition of the collagen fibers similar to those observed in CTR. CONCLUSIONS: LLLT improved the periodontal ligament and alveolar bone remodeling activity in diabetic rats during dental movement.

Effect of frequent application of low-level laser therapy on corticotomized tooth movement in dogs: a pilot study.

PURPOSE: The purposes of the present study were to evaluate the effects of frequent applications of low-level laser therapy (LLLT) on corticotomy-assisted tooth movement in a beagle dog model and to compare the effects in the mandible and maxilla. MATERIALS AND METHODS: In 4 male beagles, the maxillary and mandibular second premolars were extracted. The third premolars were corticotomized and then protracted from the canines with a continuous force of 200 g. Daily LLLT (using an aluminum gallium indium phosphide [AlGaInP] diode) was applied at the buccal mucosa of the corticotomized premolars on 1 side only. The tooth movement was measured for 8 weeks. Fluorochromes were injected intravenously at the start of the experiment (T0) and after 2 (T2), 4 (T4), and 8 (T8) weeks to evaluate new bone formation on the tension sides. Histomorphometric and immunohistologic evaluations were performed. RESULTS: In the mandible, the movement of the corticotomized premolars in the LLLT plus corticotomy group was less than that in the corticotomy-only group, although the difference was not statistically significant. In the maxilla, no significant differences between the 2 groups were found. Osteoclastic and proliferating cell activities and the amount of new bone formation were greater in the mandibular LLLT plus corticotomy group than in the corticotomy-only group. CONCLUSIONS: The frequent application of LLLT showed no significant effect on the corticotomized tooth movement.

Platelet-rich plasma, low-level laser therapy, or their combination promotes periodontal regeneration in fenestration defects: a preliminary in vivo study.

BACKGROUND: This study histomorphometrically analyzes the influence of platelet-rich plasma (PRP), low-level laser therapy (LLLT), or their combination on the healing of periodontal fenestration defects (PFDs) in rats. METHODS: PFDs were surgically created in the mandibles of 80 rats. The animals were randomly divided into four groups: 1) C (control) and 2) PRP, defects were filled with blood clot or PRP, respectively; 3) LLLT and 4) PRP/LLLT, defects received laser irradiation, were filled with blood clot or PRP, respectively, and then irradiated again. Animals were euthanized at either 10 or 30 days post-surgery. Percentage of new bone (NB), density of newly formed bone (DNB), new cementum (NC), and extension of remaining defect (ERD) were histomorphometrically evaluated. Data were statistically analyzed (analysis of variance; Tukey test, P <0.05). RESULTS: At 10 days, group PRP presented ERD significantly lower than group C. At 30 days, group PRP presented NB and DNB significantly greater than group C. Groups LLLT, PRP, and PRP/LLLT showed significant NC formation at 30 days, with collagen fibers inserted obliquely or perpendicularly to the root surface. NC formation was not observed in any group C specimen. CONCLUSIONS: LLLT, PRP, or their combination all promoted NC formation with a functional periodontal ligament. The combination PRP/LLLT did not show additional positive effects compared to the use of either therapy alone.

Influence of low-level laser on bone remodeling during induced tooth movement in rats.

OBJECTIVE: To analyze the effect of low-level laser on bone remodeling during induced tooth movement in rats. MATERIALS AND METHODS: A diode laser (808 nm, 100 mW, 54 J on an area of 0.0028 cm(2)) was used. The application was continuous, punctual, and with contact. Forty-two 70-day-old Wistar rats had the maxillary left first molar moved using a force level of 25 g. In two experimental subgroups the movement was performed over 7 days and in three subgroups the movement occurred over 14 days. In the 7-day movement subgroups, one subgroup received laser irradiation on day 1 only; the other subgroup received laser irradiation on days 1, 3, and 5. In the 14-day movement subgroups, one subgroup received laser irradiation on day 1 only; the second on days 1, 3, and 5; and the third on days 1, 3, 5, 7, 9, 11, and 13. The control group was also divided into two subgroups, and movement occurred over two different periods of treatment (7 days and 14 days) without laser application; these were used as controls for the respective experimental subgroups. Inter-subgroup comparison was performed with Kruskal-Wallis, followed by Mann-Whitney and analysis of variance, followed by Tukey tests within the 7- and 14-day subgroups. RESULTS: The subgroup with three laser applications showed significantly greater osteoclastic activity and bone resorption than the other subgroups in the 7-day movement subgroups. CONCLUSIONS: Low-level laser application significantly increased the osteoclastic but not the osteoblastic activity during the initial phases of tooth movement. In addition, the osteoclastic activity was dose-dependent.

Qualitative bone CT as a tool to assess vascularization in irradiated bone: an animal study.

OBJECTIVE: The purpose of this paper was to find a correlation between laser doppler flowmetry (LDF) and the bone mineral density quotient (BMDQ) to evaluate irradiated bone quality preoperatively. MATERIALS AND METHODS: Premolars and molars were extracted from six minipigs. After a three-month healing period, three animals received irradiation at a total dose of 24 Gy. Three months after irradiation, quantitative computed tomography was performed using a calibration bone phantom to determine the 120-position BMDQ in the alveolar bone. A drill template was created to define the exact location for measurement. LDF was then recorded after osteotomy of the residual alveolar ridge. The correlation between the BMDQ and LDF was investigated. RESULTS: There was a linear negative correlation between LDF and BMDQ in non-irradiated bone (r = -0.435, P = 0.001) and less pronounced also in irradiated bone (r = -0.309, P = 0.017). In both non-irradiated and irradiated bone, we found distinct differences between the maxilla and mandible with respect to BMDQ. However, a clear difference in mandibular and maxillary vascularity was only seen in non-irradiated bone. CONCLUSION: In non-irradiated bone, LDF and BMDQ were inversely correlated. In irradiated bone, the BMDQ alone is not an adequate preoperative tool for evaluating bone quality because it was not correlated with bone perfusion.

Effect of laser phototherapy on the hyalinization following orthodontic tooth movement in rats.

OBJECTIVE: We aimed to assess histologic changes after the use of laser phototherapy (LPT) during induced tooth movement with 40 g/F on young adult male rats. BACKGROUND DATA: Hyalinization is a sterile necrosis at the pressure zone of the periodontal ligament observed during the initial stages of the orthodontic movement, and extensive hyaline areas might cause an important delay in the tooth movement. The use of LPT is considered an enhancement factor for bone repair, as it stimulates microcirculation as well as the cellular metabolism. MATERIALS AND METHODS: Thirty animals were divided into two groups (n=15), named according to the time of animal death (7, 13, and 19 days). Half of the animals in each group were subjected to irradiation with infrared (IR) laser (λ790 nm, round shaped beam, 40 mW, continuous wave (CW), diameter=2 mm (0.0314 cm(2)), 1.273 W/cm(2), time=2×112 sec+1×275 sec (total time 499 sec), 2×142.6/4.48 J+1×350/11 J, 635.2 J/cm(2)/20 J/ session), during orthodontic movement, the other half were used as nonirradiated controls. After animal death, specimens were sectioned, processed, and stained with hematoxylin and eosin (HE) and Sirius Red, and were used for semi-quantitative histologic analysis by light microscopy. Data were statistically analyzed. RESULTS: We demonstrated that LPT positively affected an important aspect of dental movement; the hyalinization. In the present study, we found a significant reduced expression of hyalinization after 19 days. On irradiated subjects, hyalinization was increased at day 7 with significant reduction at day 13. CONCLUSIONS: It is possible to conclude that the use of laser light caused histologic alterations during the orthodontic movement characterized by increased formation of areas of hyalinization at early stages, and late reduction when compared to nonirradiated animals.

Disturbances in dental development and craniofacial growth in children treated with hematopoietic stem cell transplantation.

OBJECTIVES: To investigate the correlation between age, degree of disturbances in dental development, and vertical growth of the face in children treated with hematopoietic stem cell transplantation (HSCT). PATIENTS: 39 long-term survivors of HSCT performed in childhood and transplanted before the age of 12, at a mean age of 6.8±3.3 years. METHODS: Panoramic and cephalometric radiographs were taken at a mean age of 16.2 years. For each patient two age- and sex-matched healthy controls were included. The area of three mandibular teeth was measured and a cephalometric analysis was performed. RESULTS: The mean area of the mandibular central incisor, first and second molar was significantly smaller in the HSCT group, and the vertical growth of the face was significantly reduced, especially in the lower third, compared to healthy controls. A statistically significant correlation between age at HSCT, degree of disturbances in dental development, and vertical growth of the face was found. Children subjected to pre-HSCT chemotherapy protocols had significantly more growth reduction in vertical craniofacial variables compared to children without pre-HSCT chemotherapy. Conditioning regimens including busulfan or total body irradiation had similar deleterious effects on tooth area reduction and craniofacial parameters. CONCLUSIONS: The younger the child is at HSCT, the greater the impairment in dental and vertical facial development. This supports the suggestion that the reduction in lower facial height found in SCT children mainly is a result of impaired dental development and that young age is a risk factor for more severe disturbances.