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.

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.

Ultrasound transmission velocity for noninvasive evaluation of jaw bone quality in vivo before dental implantation

For the insertion of dental implants, mechanical bone properties at the implantation site have great impact both for therapeutic regimes as well as for the overall long-term success, making a reliable method for the preoperative assessment of the bone quality desirable. Ultrasound transmission velocity (UTV) has been introduced as a noninvasive method to analyze mechanical properties of bone. The aim of this study was the first intra-oral in vivo assessment of alveolar crest UTV values of edentulous jaws. Partly or fully edentulous patients (n = 108) were enrolled in this study, taking into account possible influence factors that affect bone quality (osteoporosis, radiation therapy). Six intra-oral measurement points were used: left side region, right side region and frontal region, for upper and lower jaw, respectively. Ultrasound transmission velocity values were measured bicortically (in bucco-oral direction) and correlated to sex, age, measurement site and history of osteoporosis or radiation therapy. We found a minimum mouth opening of 30 mm, as well as a residual alveolar ridge height of 8 mm as thresholds for a reliable intra-oral placement of the device. Xerostomia was no contraindication. Assessment of intra-oral UTV showed significantly higher values both for mandibular side regions (female 1713 +/- 153 m/s, male 1734 +/- 221 m/s) and the maxillary frontal region (female 1665 +/- 189 m/s, male 1648 +/- 82 m/s) than for maxillary side regions (female 1538 +/- 177 m/s, male 1583 +/- 90 m/s). These data were even more clarified by intra-individual correlation of upper and lower jaw side region UTV values. We found no correlation between assessed UTV values and the variables sex, age, osteoporosis or radiation therapy. The use of a small UTV device in this study allowed the recording of intra-oral UTV values in a large and heterogeneous patient collective for the first time. Assessment of alveolar-ridge UTV might offer the possibility to identify critical bone quality before implantation or to monitor bone healing (mineralization) after augmentation procedures.

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.

Effects of Nd:Yag laser irradiation on osteoblast cell cultures

The application of Nd:YAG lasers in endodontics has been explored by many investigators for different purposes. The aim of this in vitro study is to evaluate the effects of Nd:YAG laser on osteoblast cell cultures. A 1,064 nm Nd:YAG laser was used to irradiate human osteoblast-like cells (Saos-2) in noncontact mode for 10 s with different energy settings. The settings varied were pulse energy (20-120 mJ), pulse repetition rate (10-30 Hz), and power output (0.2-3.6 W). He-Ne, the aiming beam of Nd:YAG laser, was used in noncontact mode for 10 s. After 7-, 14-, and 21-day incubation period, cell viability and proliferation were evaluated with methylthiazoletetrazolium (MTT) colorometric method. The comparison of average MTT values gave no statistically significant difference between 20 mJ, 10 Hz, He-Ne, and control (p < 0.05). The differences between all other groups were significant (p < 0.05). Increase in the pulse energy, pulse repetition rate, and power output has a negative effect on the cell viability and proliferation.

Effects of 2.94 microm Er:YAG laser radiation on root surfaces treated in situ: a histological study

BACKGROUND

Previous scanning electron microscopy (SEM) studies using extracted teeth have shown the potential of infrared Er:YAG laser radiation to remove subgingival calculus without causing severe thermal changes, e.g., charring or fusion, to the irradiated root surface. The purpose of the present study was to examine the morphologic changes on root surfaces following Er:YAG laser irradiation in situ using histological observation.

METHODS

The periodontal pockets of 6 premolars, canines, and incisors that remained in situ in the jaws of human corpses were irradiated with Er:YAG laser radiation at 60 mJ, 100 mJ, or 180 mJ. The pockets were treated in a similar manner to normal clinical circumstances with a total amount of either 50 or 100 laser pulses. Following laser treatment, the entire tooth, marginal gingiva, and underlying alveolar bone were removed from the jaw. The sections were embedded in methyl-methacrylate, serially cross-sectioned, stained with hematoxylin and eosin or gallamine blue, and examined under a light microscope. Additionally, the extension of the thermally changed tissue areas was determined using digital images and histometry.

RESULTS

The histological examination revealed two kinds of thermal changes within the laser-treated root surface. Firstly, a thin superficial layer 5 to 10 microm in width was observed. The surface of this layer showed ultrastructural irregularities. Secondly, a semicircular more deeply stained area close to the apical end of the scaling track beneath the irradiated cementum was observed. The depth of this area ranged from 255 microm to 611 microm and appeared to be independent of the radiation energy.

CONCLUSION

In contrast to previous SEM studies, the histological examination indicated thermal changes within the hard tissue bordering the periodontal pocket following Er:YAG laser irradiation.

Effects of low-energy laser irradiation on bone remodeling during experimental tooth movement in rats

BACKGROUND AND OBJECTIVE

Low-energy laser irradiation has many anabolic effects such as the acceleration of bone formation. However, its effects on tooth movement, performed by bone resorption and formation, have not been well characterized.

STUDY DESIGN/MATERIALS AND METHODS

A total of 10 g of orthodontic force was applied to rat molars to cause experimental tooth movement. A Ga-Al-As diode laser was used to irradiate the area around the moved tooth, and after 12 days, the amount of tooth movement was measured. Calcein was injected subcutaneously to label the newly formed alveolar bone for quantitative analysis. Immunohistochemical staining of proliferating cell nuclear antigen was performed to evaluate cellular proliferation. TRAPase staining was also performed to facilitate the identification of osteoclasts.

RESULTS

In the laser irradiation group, the amount of tooth movement was significantly greater (1. 3-fold) than that of the nonirradiation group in the end of the experiment. The amount of bone formation and rate of cellular proliferation in the tension side and the number of osteoclasts in the pressure side were all significantly increased in the irradiation group when compared with the nonirradiation group (P < 0. 01).

CONCLUSION

These findings suggest that low-energy laser irradiation can accelerate tooth movement accompanied with alveolar bone remodeling.

Change in temperature of subjacent bone during soft tissue laser ablation

In tissues that closely approximate bone, sufficient heat may be transferred to the bone during laser surgery to cause damage and/or necrosis. To date, there have been few studies examining the temperatures elicited at the bone surface as a result of laser application to the overlying soft tissues. The purpose of this investigation was to determine, under in vitro conditions, temperature changes at the bone/soft tissue interface during laser ablation with CO2 and Nd:YAG lasers used with and without (w/wo) air/water coolant. Experimental specimens consisted of 5 mandibles from freshly sacrificed hogs; laser treatment sites were the buccal and lingual attached gingiva of the molars and the lingual keratinized mucosa of the incisor region. CO2 and Nd:YAG lasers were used w/wo coolant at power settings of 4 to 8 W and 5 to 9 W, respectively. Temperature changes were measured with a copper constant thermocouple contained within a 21 gauge hypodermic needle. In comparing the lasers at comparable energy densities w/wo coolant, temperature increases at the bone/soft tissue interface ranged from 8.0 to 11.1 degrees C with the Nd:YAG and 1.4 to 2.1 degrees C with the CO2. Similarly, in comparing the times required for the interface to return to baseline temperature following removal of the laser, values ranged from approximately 143 to 205 and approximately 119 to 139 seconds for the Nd:YAG and CO2, respectively. Results from this study suggest that, at energy densities equal or above those reported here, the increase in temperature at the bone surface as a result of periodontal soft tissue surgery with the Nd:YAG laser could be damaging, especially if the exposure is prolonged.

Oral implant rehabilitation in irradiated patients without adjunctive hyperbaric oxygen

In 15 patients treated for malignant tumors in the maxillofacial region, 90 Brånemark implants have been placed in irradiated alveolar bone without adjunctive hyperbaric oxygen therapy. Seventy-eight implants were placed in the mandible and 12 in the maxilla. After a follow-up period of 1 to 8 years, 88 implants are still stable, 27 after 6 to 8 years, 44 after 3 to 4 years, and 17 after 1 to 2 years. Two patients lost 1 implant each, both at an early stage. The success rate is 97.8% according to remaining implants, and prosthesis stability is 100%. Implant treatment for oral rehabilitation can be carried out as a safe and successful procedure in the irradiated patient without adjunctive hyperbaric oxygen therapy.

Attenuation of x-ray in muscle and alveolar bone during mandibular premolar periapical radiographic procedure

The main purpose of this study is to find out the degree of attenuation when the x-ray entrances the skin and reaches the film at the bone area near the mandibular premolar root apex. In this study we used thermaluminescent dosimeters (TLDs) to measure the entrance dose and exit dose directly at the area of interest and calculated the penetration value P. We also simulated the attenuation process and calculated the P value in similar conditions. The results indicate that the mean P value of direct measurement from patient is 0.071 +/- 0.018 (60kVp, HVL = 1.5mm Al), while that for theoretical calculation is 0.06458 at 27keV. We concluded that P value of direct measurement can match with the theoretical value and further studies in jaw bone density and other related portions is worthwhile.

The effect of cobalt-60 irradiation on bone marrow cellularity and alveolar osteoclasts

The purpose of this study was to investigate the mechanisms of bone resorption in the rat dentoalveolar complex occurring as a result of orthodontic appliance therapy. Utilizing whole body radioactive cobalt 60 (Co60) irradiation in combination with orthodontic tooth movement, the activation, recruitment, and life span of osteoclasts was studied. Thirty-four adult Fischer 344 rats were irradiated with 10 and 20 Gray of Co60. Twelve days after irradiation, each rat was fitted with an orthodontic appliance; the rats were sacrificed 7, 14, or 21 days after appliance placement. To serve as controls, another group of 12 rats was subjected to orthodontic treatment only. Histologic sections were prepared from decalcified maxillary alveolar process, and osteoclasts were counted. In the control group, osteoclasts were presence in the periodontal membrane for four weeks after appliance placement, and the largest number of osteoclasts was observed in the second week. The smaller total irradiation dose (10 Gray, administered in 5 daily fractions) induced a transient reduction in the bone marrow cell count of more than 90%, followed by a complete rebound. The peak osteoclst number also was increased 110%. In contrast, the higher total dose (20 Gray, administered in 10 daily fractions) resulted in a reduction of 60% in bone marrow cellularity and a decrease in the peak osteoclast number by 40%. Fluctuations in bone marrow cellularity generally corresponded to similar variations in the osteoclast number, but there was an apparent lack of correspondence between bone marrow cell and white blood cell values. The total period of osteoclastic presence in the periodontal membrane following orthodontic activation, normally four weeks in duration, was reduced by one week in the irradiated animals. These findings lead us to speculate that the mechanisms of osteoclast activation and recruitment following orthodontic appliance therapy may involve three consecutive waves of osteoclast maturation. The total duration of osteoclastic bone resorption lasts 4 weeks, but the osteoclast lie span is calculated to be 9 to 10 days (9 days x 3 waves = 27 days). If the results of this study are proved to be reproducible, a scientific basis may have been provided to support the common practice in orthodontics wherein the duration between orthodontic appointments is 4-5 weeks.

Evaluation of the effects of diagnostic radiation on titanium dental implant osseointegration in the micropig

The effect that diagnostic radiation may have on peri-implant supporting alveolar tissues is not well understood. Fifty-four (54) titanium dental implants were inserted into the posterior mandible of nine micropigs. At implant placement surgery, 18 implants were exposed to either 2 (diagnostic) or 10 (excessive) doses of diagnostic radiation; the remaining 36 implants served as controls. Fourteen weeks after implant placement, standardized clinical radiographs were taken, pigs were euthanized, and implants with supporting alveolar tissues were prepared and examined by light and scanning electron microscopy (SEM). Ninety-seven sections were evaluated by SEM for morphometric and morphologic analyses. The mean percent of implant length in contact with bone was 47% for the controls and 53% for the implants receiving radiation. Five implants were lost during the initial healing phase and four implants were clinically mobile at time of euthanasia, giving a success rate of 83% (45/54). Correlative light microscopy of peri-implant supporting tissues revealed no distinct differences between the microvasculature of controls versus implants exposed to radiation. Standardized clinical radiographs revealed crestal saucerization in both control and radiated implants. This study revealed no statistically significant difference for the percent of implant length in contact with alveolar bone for controls or implants exposed to 2 or 10 doses of diagnostic radiation at implant placement time.

Severe progressive periodontal destruction due to radiation tissue injury

Cancer radiotherapy to the head and neck region results in short- and long-term radiation tissue injuries. Radiation bone injury is a long-term manifestation which could progress to osteoradionecrosis. A case of radiation tissue injury to the periodontium is presented. The possible pathogenesis of these events is described as they relate to the sequential radiographic changes observed over a period of 6 years until the involved teeth were exfoliated. The post-irradiation management of the teeth with advancing periodontal disease in the path of irradiation was by conservative means, including good personal oral hygiene care, scaling and root planing, periodic chlorhexidine irrigation, and topical fluoride application.

[A prospective study of alveolar bone resorption after radiotherapy and chemotherapy]

A prospective comparative study of the alveolar bone resorption after teeth extraction was achieved in a series of 79 patients in order to analyze macroscopically the possible consequences of radiotherapy and chemotherapy on the toothless edges. After quarterly coronal and sagittal X-rays for two years, this study enhances quite a similar vertical resorption for the radiation and chemotherapy-treated patients as well as for the witness patients. The alveolar bone resorption progression also appears unaltered by anti cancerous treatments. In both cases, a resorption stabilisation can be clearly seen after 6 months according to dental extractions. The vertical alveolar bone resorption is more important in incisor and canine regions. The anti cancerous treatments may not have significant disastrous consequences as far as available bone amount is concerned, on a post prosthetic restoration.

A randomised double blind comparative study of low level laser therapy following surgical extraction of lower third molar teeth

A randomised, double blind comparative study was undertaken to assess the efficacy of low level laser therapy in the reduction of postoperative pain and swelling in patients undergoing the extraction of bilaterally impacted mandibular third molar teeth. Healing of the sockets was also compared after 1 week. A group of 64 patients had one randomly-selected operation side treated with a semi-conductor laser and the other side with an apparently identical but non-operating model. Complete data were obtained from 52 of the 64 patients. The results showed that there was no evidence of a difference in pain and swelling on the third day after operation between laser and placebo sides. There was no difference between the two sides when they were assessed for healing 7 days after surgery.

Effect of a pulsing electromagnetic field on demineralized bone-matrix-induced bone formation in a bony defect in the premaxilla of rats

A 2-mm non-healing bony defect was prepared in the premaxilla of male Wistar rats weighing about 180 g as a simulation of an alveolar cleft, for determination of whether a pulsing electromagnetic field (PEMF) could promote regeneration of bone induced by demineralized bone matrix (DBM). The defect was either treated with 7 mg DBM or was left as a non-grafted control. The rats were exposed to a PEMF with a frequency of 100 Hz, a 10-ms-wide burst with 100 microseconds-wide quasi-rectangular pulses, repeating at 15 Hz, and magnetic field strength of 1.5-1.8 G. Alkaline phosphatase activity increased significantly from day 7 in the DBM-graft-plus-PEMF group and from day 10 in the DBM-graft group, reaching a maximum on day 14. A greater-than-two-fold rise in alkaline phosphatase activity and a three-fold rise in the amount of 45Ca incorporation in the DBM-graft-plus-PEMF group were attained compared with those of the DBM-graft group. The DBM-graft-plus-PEMF group produced more bone with almost complete osseous bridging in the defect sites than did the group treated with DBM only on day 35. The findings indicate that PEMF had an enhancing effect on the bone-inductive properties of the DBM through the stimulation of osteoblast differentiation induced by DBM.

Orthodontic magnets: effects on gingival epithelium and alveolar bone in monkeys

The purpose of the present study was to examine soft and hard oral tissues in contact with or close to orthodontic magnets following an extended exposure time. Two male monkeys were used in the experiment. Individual silver splints covering the teeth from 17 to 27 in the upper jaw and 32-42 in the lower jaw were made. Co5Sm magnets were inserted with cold-curing acrylic buccally and lingually in the splints. The monkeys were injected with tetracycline at the start of the experiment and after 4 weeks. The epithelial thickness in buccal and lingual mucosa under the magnets and corresponding sites on the control side were estimated. The intensity of tetracycline fluorescence in the bone under the magnets and corresponding control sites was assessed semiquantitatively. A thinner epithelium compared to the controls and a patchy tetracycline-incorporation in the bone adjacent to orthodontic magnets in contrast to a homogeneous tetracycline fluorescent pattern in the controls were the most conspicuous findings. It cannot be excluded that the magnetic field or corrosion products from the magnetic material influenced vital processes in the epithelium and the bone close to the magnets. However, it cannot be concluded from the present study what cellular processes were affected.

The effect of therapeutic radiation on canine alveolar ridges augmented with hydroxylapatite

The purpose of this investigation was to evaluate the effect of radiation on hydroxylapatite (HA) implanted subperiosteally for alveolar ridge augmentation in dogs. All bicuspids and molars were extracted from 16 dogs. After 6 weeks, nonporous HA granules were implanted subperiosteally on the alveolar ridge. Following 4 months of healing, 12 dogs (experimental group) underwent therapeutic radiation therapy (Co60, 4,000 rad [40 Gy]) to the head and neck region. Four dogs were not irradiated and served as controls. Four animals (three experimental and one control) were killed at 5,6,7, and 8 months after HA augmentation. Light microscopic evaluation showed that approximately 25% of HA granules were encased by bone while the others were surrounded by fibrous connective tissue. Dissolution of the HA was observed. Microparticles of HA were phagocytized as part of a granulomatous inflammatory reaction. This reaction decreased significantly as time elapsed after implantation. Osteoclastic activity was seen at the junction of HA and periosteum and as part of bone remodeling. Dissolution of the HA granules and the granulomatous inflammatory reaction were not significantly increased by therapeutic radiation. The radiation did not cause development of dehiscence or osteonecrosis.

Mandibular growth and tooth eruption after localized x-radiation

The effect of localized x-radiation on the growth of mandibular bone and molar eruption was evaluated by morphometric methods. A dose of 20 Gy of x-radiation was given to the molar zone of growing rats. The animals were then killed in groups at 30 and 60 days postirradiation. Two groups of nonirradiated, age-matched rats were used as controls. Parameters related to molar eruption, mandibular length, and mandibular height were measured on lateral radiographs. The results obtained showed that the values of the biometric parameters were lower in experimental than in control animals. Odontoblastic atrophy, alveolodentary ankylosis, and meager or no root formation were the most conspicuous histologic findings. Osteodentin was found between canaliculary dentin and bone in cases of ankylosis. The morphometric data presented confirm the probability of alterations in mandibular growth and tooth eruption following x-radiation and suggest that this be considered in planning radiotherapy in children.

Tissue response following CO2 laser application in apical surgery: light microscopic assessment in dogs

The potential advantages of CO2 laser in apical surgery have not been established histologically. Therefore, the long-term effects of CO2 laser on the apical and periapical tissues were examined histologically in dogs 6 months after apical surgery. Lased specimens and unlased controls showed periapical inflammatory and osteogenic reactions. Lased root surfaces revealed craters with a superficial charred layer closely associated with new cementum-like matrix. The subjacent dentin appeared tubule-free and eosinophilic. Lased bone trabeculae showed a charred layer with a deeper osteocyte-free zone. The charred layer was covered by new bone. Detached charred segments in the marrow space and periapical inflammatory infiltrate were intimately associated with multinucleated giant cells, some containing minute char particles. Such cells were absent from the root and trabecular char linings. In addition, the charred surfaces were free of hard tissue resorption. These results suggest that CO2 laser does not hinder healing when applied in apical surgery.

Postradiation dental extractions without hyperbaric oxygen

This study examined the incidence of osteoradionecrosis after tooth extraction with low-epinephrine or epinephrine-free, nonlidocaine local anesthetics and conservative surgical techniques. Estimates of the absorbed radiation dose on irradiated alveolar bone were made by reviewing radiotherapy records. This investigation included 72 patients ranging in age from 22 to 80 years (median 57.4 years). We removed 449 teeth. Analysis of radiotherapy check films revealed that only 196 teeth (44%) were included within the treatment volume. The median prescribed tumor dose was 50 Gy (range 25 to 84 Gy) in 20 fractions (range 10 to 37), with a median dose per fraction of 2.5 Gy (range 1.88 to 3.14 Gy). Follow-up time ranged from 68 days to 19.3 years (median 4.8 years). No instances of osteoradionecrosis occurred as a result of dental extraction with this conservative method.

[A comparative study of mandibular alveolar resorption following radiotherapy and/or chemotherapy in man]

A prospective study of mandibular alveolar bone resorption has been achieved on 49 patients with upper aerodigestive tract tumor and treated by radiation therapy and/or a chemotherapy, on 30 patients who were not treated. All these patients were subjected to dental extractions followed by X rays in coronal and sagittal view, during at least one year, at the rate of one X ray every three months. The comparative study enabled to show a quite similar resorption for the two population, a slightly more important resorption on incisor and canine regions, and a stopping of the resorption about five months later according to dental extractions. Radiation therapy and chemotherapy (therapeutic doses) may not have significant influence on alveolar bone resorption after dental extractions.

Recurring giant-cell granuloma at the site of previous radiation therapy

A 15-year-old girl presented with an aggressive giant-cell granuloma (GCG) of the maxilla with local invasiveness and bony destruction. The tumor recurred twice and attained a diameter of 6 cm. Previously, this patient had had two hematologic malignancies for which she had received therapeutic doses of radiation to the site where the GCG occurred. It is therefore possible that this tumor was radiation induced.

[Management of oral problems after radiation of the head and neck]

In this article we discuss the various oral problems that afflict the patient undergoing radiation therapy for malignant disease involving the head and neck, the effects of which may be physiologically disastrous unless the patient is forewarned and the problems managed effectively. The oral complications arise as a result of radiation injury to the salivary glands, oral mucosa and alveolar bone mainly. They may vary in duration and intensity, but may be found to a greater or lesser extent in most patients.

[The effect of radiation on the chronology of extraction wound healing. Histomorphologic study in rats]

The purpose of this study was to analyse histomorfologically the X-radiation influence on the chronology of wound healing of tooth extraction. Sixth young albino rats were used. After extracting the maxillary right incisors all the rats, three experimental groups were formed: the control (I) and the groups that received 1.25 Sv (II) and 1.75 Sv (III). The rats were killer at 3, 7, 14 and 28 post-operative days following the teeth extraction. The pieces obtained were submitted to routine laboratorial procedures until getting pieces stained with hematoxylin and eosin. It was concluted that: 1) there was a delay in the epithelial proliferation of the gengival mucosa o the animals submitted to X-rays, in a similar way in the two irradiated groups: 2) there was a considerable delay in the alveolar repair process in dental extraction wound; 3) this delay was more proeminent when the X-ray action was more intense.

A contemporary perspective on techniques for the clinical assessment of alveolar bone

Radiographic techniques, traditional ones as well as newer ones under development, for clinically assessing alveolar bone are critically assessed. Traditional intraoral radiography is reexamined, in particular with regard to the accuracy with which the alveolar crest is seen. Evidence is presented for a more accurate representation of the alveolar crest on bitewings rather than periapical films. Application in periodontics of newer radiographic techniques, subtraction radiography, and single and dual photon aborptiometry presently under clinical development are discussed in regard to their potential and limitations. Similarly, radiopharmaceuticals to evaluate the metabolic status of alveolar bone are discussed as well as the potential for using analyses of gingival crevice fluid as a window for assessment of alveolar crest metabolism.

Irradiation effect of low-energy laser on alveolar bone after tooth extraction. Experimental study in rats

A histopathological study of the initial healing of extraction wounds following low-energy laser irradiation, using a gallium-arsenide semi-conductor laser, was carried out in rats. The results suggest that this mode of treatment has a beneficial effect on initial bony wound healing. It was found that proliferation of fibroblasts was more prominent in the irradiated group, and so was the formation of trabecular osteoid tissue. The deposition of lead in the newly formed bone suggests a more rapid ossification in the irradiated group.

Alveolar wound healing after x-irradiation: a histologic, radiographic, and histometric study

Healing of extraction wounds in rats following cephalic irradiation was studied by histologic, radiographic, and histometric methods 14 days after tooth extraction. Irradiation was given at 0, 3, and 7 days after surgery in doses of either 15, 20, or 30 Gy. No significant differences were seen with the different doses given seven days post-extraction. However, socket healing was delayed when irradiation was given immediately and three days after extraction. On the basis of these observations, it is recommended that radiation not begin until at least one week after the extraction of teeth.

Effect of diphosphonate on the prevention of X-radiation-induced inhibition of bone formation in rats

A histologic and histometric study of the effect of EHDP (ethane-1-hydroxy-1,1-diphosphonate) on the alveolar wound healing of irradiated animals is presented. This drug was selected based on its osteosclerotic effect when applied at low doses. The three left mandibular molars of 80 male Wistar rats were extracted. The rats were grouped into 4 sets of 20 rats each. Group I received no further treatment; Group II received daily intraperitoneal injections of EHDP (7.5 mg/Kg of body weight during 10 days); Group III: 15 Gy of X-radiation were applied to the head; and Group IV were irradiated and injected with EHDP as were animals of Groups III and II. Half of the animals were killed after 14 days and the other half 30 days post-extraction. Sections were made at the level of the mesial socket of the first molar in a bucco-lingual orientation, on which histometric determinations of bone activity were made. The results showed the attenuation of the inhibitory effect of radiation on bone formation when the animals were treated with EHDP.

Early radiographic changes in radiation bone injury

A chronologic series of periapical radiographs was evaluated for the purpose of detecting damage to bone and tooth-supporting tissues in a patient receiving radiation therapy for a basal cell carcinoma of the mandibular gingiva. Widening of the periodontal space was one of the early radiographic changes observed. It is suggested, from the sequence of radiographic changes, that radiation-induced changed in the circulatory system of the bone might be primarily responsible for the resulting changes.

Effect of X-ray irradiation on primary mineralization in rat alveolar bone

The effect of X-ray irradiation on the process of primary mineralization in bone was studied by biochemical and ultrastructural methods. A single dose of 1500R was administered to the head region of rats. The animals were examined immediately after irradiation and 1, 2 and 3 weeks later. Fractions of isolated cells and extracellular matrix vesicles were prepared from the maxillary alveolar bone of irradiated and untreated rats by collagenase digestion and differential centrifugation. The protein content and activities of vesicular phosphatases were determined in both fractions. A continuous decrease in the activity of alkaline phosphatase could be observed in both cell and matrix vesicle fractions during a three-week follow up after irradiation. Acid phosphatase activity decreased only in the vesicle fraction. Transmission electron microscopy of irradiated bone tissue revealed that many matrix vesicles were devoid of intact membranes and apatite crystals. Calcifying nodules were abundant in the matrix without their apparent fusion into larger mineralized structures. It is suggested that irradiation interferes with enzymatic processes associated with primary mineralization.

Effects of radiation on the developing dentition and supporting bone

Underdevelopment of teeth after exposure to radiation has been observed since the early experiments with X rays. Two patients had been irradiated at young ages for embryonal rhabdomyosarcomas. For the patient treated with radiation at age 4 for a lesion in the submandibular area, root development of the mandibular teeth stopped, but the teeth nevertheless erupted. In the patient treated with radiation at age 9 for a tumor in the left cheek, bone apposition in the left side of the mandible failed to continue at the same rate as on the right side. Although new megavoltage radiation machines have reduced the chances of bone complications in adults, developing bone and structures are still significantly affected by radiation.

Effect of irradiation-timing on the initial socket healing in rats

The effect of a single dose of 1500 R on early postextraction socket healing was studied in jaws of rats. A severe delay in healing was found in animals irradiated 2 weeks prior to extraction. Retardation of healing to a lesser degree was demonstrated in sockets irradiated immediately after exodontia.

Radiographic findings in 224Ra-caused dental resorptions

Dental resorptions as a delayed effect of Thorium X (224Ra) were observed in four patients. The radiographic findings showed distinct and representative patterns. Apparently, the observed changes are typical for delayed alterations related to 224Ra-specific disturbances in the alveolar process. Degenerative and inflammatory reactions may also be involved in the pathogenesis.

Complete denture prosthodontics for the radiation patient

The increased use of radiation therapy for the control of oral cancer necessitates that all dentists concerned with the rehabilitation of oral cancer patients be familiar with this treatment modality. Radiologic equipment, the rationale for their use, and the sequelae to oral treatment are discussed. Misconceptions have developed concerning the advisability of prescribing complete dentures following radiation therapy. However, clinical experience in the Maxillofacial Unit at the University of California, San Francisco, indicates that most radiation patients can wear complete dentures. The need to follow sound prosthodontic techniques is advocated, along with a few modifications related specifically to the radiation patient. Patient cooperation and meticulous care during and following the placement of dentures are stressed to minimize the risk of tissue necrosis and to preserve the well-being of the patient.