Bone formation after implantation of autolysed antigen extracted allogeneic bone in ovariectomized rabbits.

This study was undertaken to evaluate the bone formation response to AAA bone in healthy and oestrogen deficient animals. Seventeen young healthy New Zealand female rabbits were used. Nine rabbits were subjected to ovariectomy and the remaining eight were sham-operated. Four weeks after ovariectomy standardized round cavities, 5mm in diameter, were made medially in the cortical part of each proximal tibia. To half of the cavities autolysed antigen-extracted allogeneic AAA bone granules were added. After another 8 weeks the animals were sacrificed and sections of the tibial experimental areas were obtained. These were studied in light microscopy and the bone and non-bone areas were measured with computer support. The study showed that the addition of a bone inductive substance such as AAA bone enhances bone formation also in oestrogen deficient animals.

Bacteria inhibit biosynthesis of bone matrix proteins in human osteoblasts.

The effect of extracts from Staphylococcus aureus and Staphylococcus epidermidis on bone matrix production were assessed by analyzing the biosynthesis of osteocalcin and Type I collagen in a human osteoblastic osteosarcoma cell line (MG-63). In MG-63 cells, extracts from Staphylococcus aureus and Staphylococcus epidermidis decreased 1,25(OH)2-vitamin D3 stimulated osteocalcin biosynthesis, and insulin-like growth factor I induced production of Type I collagen in a concentration dependent manner. The basal rate of osteocalcin and Type I collagen formation was unaffected by the bacterial extracts. The inhibitory effect of the bacteria on osteocalcin biosynthesis was seen after 24 hours of treatment and was maintained for at least 96 hours. The extracts of Staphylococcus aureus and Staphylococcus epidermidis enhanced prostaglandin E2 formation in the MG-63 cells. Abolition of the prostaglandin E2 response by treatment with indomethacin and flurbiprofen did not affect bacteria induced inhibition of osteocalcin production. Stimulation of osteocalcin biosynthesis by 1,25(OH)2-vitamin D3 was associated with a decreased rate of cell proliferation. The inhibitory action of the bacterial extracts was not linked to any inhibition of [3H]-thymidine incorporation into deoxyribonucleic acid. These data show that extracts of Staphylococcus aureus and Staphylococcus epidermidis have the ability to inhibit the biosynthesis of bone matrix proteins by a nonprostaglandin and noncytotoxic dependent mechanism and suggest that bone loss in inflammatory processes containing Staphylococcus aureus or Staphylococcus epidermidis may not be caused only by enhanced bone resorption but also by decreased bone formation.

Cystatin C, and inhibitor of bone resorption produced by osteoblasts.

The effects of human cystatin C on bone resorption, enzyme release, osteoclast generation, bone cell proliferation and bone matrix protein biosynthesis have been examined in different in vitro systems. The effects of cystatin C were compared with those of calcitonin and E 64 (trans-Epoxysuccinyl-L-leucyl-amido-(4-guanidino)butane). Recombinant human cystatin C and E 64 dose dependently inhibited the mobilization of 45Ca and the release of 3H (from [3H]-proline-labelled bones) in mouse calvariae stimulated to resorb by parathyroid hormone (PTH) or 1,25(OH)2-vitamin D3. Cystatin C and E 64 also inhibited the release of 45Ca from bones stimulated by thrombin, interleukin-1 and prostaglandin E2. In PTH-stimulated bones, the inhibitory action of cystatin C and E 64 on 45Ca release was observed after 6-9 h, whereas the inhibitory effect on 3H release was seen after just 2 h. In contrast, calcitonin caused an inhibition of both 45Ca and 3H release which was seen after 2 h. The PTH-stimulated release of the lysosomal enzymes was not affected by cystatin C and E 64, whereas calcitonin caused a significant inhibition. In contrast to calcitonin, cystatin C did not affect PTH-stimulated enhancement of osteoclast generation in the mouse calvariae. Using Western blot analysis and radioimmunoassay, we demonstrated that mouse calvarial bones and MC3T3-E1 cells produce cystatin C. These data show that cystatin C is synthesized by bone cells and that recombinant human cystatin C inhibits bone resorption in vitro without affecting bone cell proliferation, bone matrix formation or osteoclast generation. The mechanism seems to be due primarily to inhibition of the activity of osteoclastic proteolytic enzymes released into the resorption lacunae.

Autogenous onlay bone grafts fixed with screw implants for the treatment of severely resorbed maxillae. Radiographic evaluation of preoperative bone dimensions, postoperative bone loss, and changes in soft-tissue profile.

Thirty patients with severely resorbed edentulous maxillae underwent combined treatment of iliac bone onlay graft and titanium implants. The patients were followed for 3 years. They were radiographically examined before surgery to evaluate the bone volume at the intended implant sites. Only 13/156 implant sites were suitable for implant insertion. The bone level at the implant surfaces was evaluated after 6 months and 1, 2, and 3 years, respectively. There was a continuing decrease of the bone level throughout the follow-up period with a mean loss of 4.9 mm after 3 years and with no difference between sexes. Twenty-six implants were radiographically examined before removal, and only three of these implant sites showed radiographic signs of failure. The soft-tissue profile was analyzed cephalometrically by the subtraction technique. The upper lip generally moved inward and the apex of the nose and the columella downward and inward. The anterior facial height increased in most of the patients, resulting in a downward and inward change of the lower lip, the mentolabial sulcus, the soft-tissue pogonion, and the soft-tissue gnathion.

Cytokine-induced inhibition of bone matrix proteins is not mediated by prostaglandins.

Interleukin-1 (IL-1) and tumor necrosis factor (TNF), two pleiotropic cytokines produced in inflammatory processes, inhibit bone matrix biosynthesis and stimulate prostanoid formation in osteoblasts. In the present study, the importance of prostaglandin formation in IL-1 and TNF-induced inhibition of osteocalcin and type I collagen formation has been examined. In the human osteoblastic cell line MG-63, IL-1 alpha (10-1000 pg/ml), IL-1 beta (3-300 pg/ml) and TNF-alpha (1-30 ng/ml) stimulated prostaglandin E2 (PGE2) formation and inhibited 1,25(OH)2-vitamin D3-induced osteocalcin biosynthesis as well as basal production of type I collagen. Addition of PGE2 or increasing the endogenous formation of PGE2 by treating the cells with arachidonic acid, bradykinin, Lys-bradykinin or des-Arg9-bradykinin, did not affect osteocalcin and type I collagen formation in unstimulated or 1,25(OH)2-vitamin D3-stimulated osteoblasts. Four non-steroidal antiinflammatory drugs, indomethacin, flurbiprofen, naproxen and meclofenamic acid, inhibited basal, IL-1 beta- and TNF-alpha-stimulated PGE2 formation in the MG-63 cells without affecting IL-1 beta- or TNF-alpha-induced inhibition of osteocalcin and type I collagen formation. In isolated, non-transformed, human osteoblast-like cells, IL-1 beta and TNF-alpha stimulated PGE2 formation and concomitantly inhibited 1,25(OH)2-vitamin D3-stimulated osteocalcin biosynthesis, without affecting type I collagen formation. In these cells, indomethacin and flurbiprofen abolished the effects of IL-1 beta and TNF-alpha on prostaglandin formation without affecting the inhibitory effects of the cytokines on osteocalcin biosynthesis. These data show that IL-1 and TNF inhibit osteocalcin and type I collagen formation in osteoblasts independently of prostaglandin biosynthesis and that non-steroidal antiinflammatory drugs do not affect the effects of IL-1 and TNF on bone matrix biosynthesis.

Effects of bradykinin and thrombin on prostaglandin formation, cell proliferation and collagen biosynthesis in human dental-pulp fibroblasts.

Bradykinin and thrombin caused a time- and dose-dependent stimulation of prostanoid biosynthesis in human dental-pulp fibroblasts, as assessed by the release of prostaglandin E2 (PGE2) and 6-keto-prostaglandin F1 alpha (the stable breakdown product of prostacyclin). The stimulatory effect of bradykinin and thrombin on PGE2 biosynthesis was maximal within 5-10 min. The concentration of bradykinin producing half-maximal stimulation (EC50) of PGE2 and prostacyclin formation was 10 nM. EC50 for thrombin-induced formation of PGE2 and prostacyclin were 0.05 and 0.2 U/ml, respectively. Bradykinin analogues with affinity to the bradykinin B2 receptor, but not those with affinity to the B1 receptor, caused a burst of PGE2 formation. The stimulatory action of bradykinin and thrombin on PGE2 biosynthesis was abolished by two structurally different cyclo-oxygenase inhibitors and significantly reduced by two corticosteroids. Thrombin dose-dependently enhanced the incorporation of [3H]-thymidine into DNA in pulpal fibroblasts by a mechanism that was unrelated to the effect on prostanoid biosynthesis. Bradykinin did not affect thymidine incorporation. Thrombin, but not bradykinin, stimulated the biosynthesis of type 1 collagen in the pulpal fibroblasts. The stimulatory effect of thrombin on collagen biosynthesis was not affected by cyclo-oxygenase inhibitors. These data show that human dental-pulp fibroblasts are equipped with receptors for bradykinin and thrombin linked to enhanced prostanoid biosynthesis. Occupancy of the thrombin receptors also leads to a prostaglandin-independent stimulation of cell proliferation and collagen biosynthesis.

Oral implant rehabilitation of patients with oral malignancies treated with radiotherapy and surgery without adjunctive hyperbaric oxygen.

Five patients treated with radiotherapy and surgery for oral malignant tumors had a total of 20 Brånemark implants placed in irradiated bone of the mandible. The radiotherapy dose varied between 25 and 64 Gy (mean 40.3 Gy) with a biologically effective dose varying between 33.4 and 106.9. One implant did not osseointegrate, but 19 remain stable after 3 to 6 years of observation. The oral surgery procedures were carried out without adjunct hyperbaric oxygen therapy, and the successful results support the view that such adjunctive measures are not always necessary in the oral rehabilitation after radiotherapy.

Bone healing after implantation of hydroxyapatite granules and blocks (Interpore 200) combined with autolyzed antigen-extracted allogeneic bone and fibrin glue. Experimental studies on adult rabbits.

Bone healing around hydroxyapatite granules and blocks (Interpore 200), implanted in mandibular and tibial bone cavities with or without autolyzed, antigen-extracted, allogeneic (AAA) bone, was studied in young adult rabbits. The study was done in two series. In series I, standardized bone cavities were filled with implants in granular form mixed with a fibrin glue, Tisseel, for half of the cavities. The animals were followed for 5 and 8 weeks. In all cavities implanted with AAA bone, regardless of the combination with hydroxyapatite or the fibrin glue, bone had formed in excess of the cavities, resembling exostosis formation. AAA bone significantly increased (P < 0.005 or 0.01) bone formation. In series II, a 6 x 3-mm cavity was created in the medial aspect of the proximal part of each tibia. This was filled with a hydroxyapatite block--its cross section measuring 6 x 3 mm--such that 2 mm of the block extended outside the bone surface. In alternation between left and right sides, half of the blocks were covered with a paste of AAA bone and Tisseel, and half with Tisseel with the fibrin glue alone. The observation time was 8 weeks. The area of newly formed bone within and around the hydroxyapatite blocks was significantly increased (P < 0.001) when AAA bone was used. Thus, hydroxyapatite, both as granules and blocks for supporting structures, can be successfully combined with AAA bone, the bone-inductive capacity of AAA bone being utilized.

Sensitivity to a low calcium diet in different bones: an experimental study in the adult rat.

Adult male Sprague-Dawley rats weighing an average of 550 g were age matched into one control group and one group given a low calcium diet. The animals were followed for 34 wk. There was a similar loss of cancellous bone tissue in the proximal tibia, the first tail vertebra and the mandible due to calcium deficiency. The bone loss was not related to the initial amount of cancellous bone or to the bone-forming activity, which did not differ between experimental and control animals.

Short term bone healing in calcium deficiency osteopenia and disuse osteopenia: experimental studies in adult rats.

Adult male Sprague-Dawley rats (average weight 530-540 g) were studied in two different series. In series I, studying disuse osteopenia, the experimental rats had all maxillary molars extracted on one side. After 16 wk they had their mandibular first molar of the corresponding side extracted and were followed for another 4 wk. In series II, studying calcium deficiency osteopenia, the experimental rats were given a low calcium diet for 16 wk and at this time had their mandibular first molars extracted. Both disuse and calcium deficiency caused osteopenia, which did not seem to impair the healing process after tooth extraction in the short term. One puzzling finding in the disuse series (I) was that the alveolar height at the extraction site was higher in the experimental than in the control group 4 wk after extraction.

Occlusion of the incisal canal with bone chips. A procedure to facilitate insertion of implants in the anterior maxilla.

In 4 patients, who had lost one or both central maxillary incisors due to trauma, the incisal canals were filled with autogenous cancellous bone harvested from the chin. After a healing period of 4-5 months implants were inserted. At the time of implant surgery in all cases the canal appeared to be replaced by cancellous bone and the implants were placed partially into the grafted area. After another 6 months abutments were connected and crowns made. After follow-up of between 12 and 15 months no fixture has been lost.

Does midazolam sedation in oral surgery affect the potency or duration of diflunisal analgesia?

A randomized cross-over study was carried out to determine whether midazolam in doses used for conscious sedation had any effect on the potency or duration of diflunisal, a non-narcotic analgesic used for postoperative pain in oral surgery. Thirty-two Hong Kong Chinese patients of either sex, aged between 16 and 28 years, were given either midazolam to supplement local anaesthesia or local anaesthesia alone at one visit and the alternative at the other visit, for surgical removal of bilateral symmetrically impacted third molars. Surgery was carried out on one side only at each visit. Diflunisal was given for postoperative pain relief. Midazolam had no effect on the potency or duration of action of diflunisal. Independent of the method, more patients had better pain relief following the second procedure than following the first, probably due to a degree of adaptation to the pain, at the second visit.

Cardiac dysrhythmias with midazolam sedation.

A randomized cross-over study was made of 32 young healthy Hong Kong Chinese to compare the incidence and nature of dysrhythmias that occurred during third molar surgery done under local anesthesia, alone or supplemented with midazolam sedation. The incidence of dysrhythmias during surgery was not significantly different during the two procedures. However prior to surgery, 25% of the patients had dysrhythmias during sedation with midazolam. The majority of dysrhythmias were infrequent unifocal ventricular ectopics. During sedation with midazolam it may be beneficial to monitor the electrocardiogram, especially in high risk patients such as those suffering from ischaemic heart disease, cardiomyopathy, and those on antidysrhythmic drugs.

Effect of conscious sedation with midazolam on oxygen saturation.

A randomized cross-over study was done to determine if significant oxygen desaturation occurs during third molar surgery under conscious sedation with midazolam to warrant supplementary oxygen. Thirty-two healthy patients of either sex, between the ages of 18 and 40 years, had bilateral symmetrically impacted lower third molar surgery under local anesthesia in two visits. Randomly at one visit the local anesthesia was supplemented with midazolam sedation. Continuous monitoring of oxygen saturation, blood pressure, and pulse were carried out. At the rate of injection with the dose of midazolam used, no significant desaturation attributable to midazolam sedation was observed. However, short periods of significant desaturation occurred with both procedures. These episodes, though of no consequence to healthy people, may produce problems in compromised patients, and indicate the importance of monitoring of oxygen saturation in all patients during minor oral surgery procedures.

Isoflurane for conscious sedation.

Isoflurane 0.5% in oxygen for conscious sedation was compared with placebo (oxygen) and with an equipotent concentration of nitrous oxide in oxygen, in patients scheduled for surgical removal of bilateral, similarly impacted lower third molars. The majority of patients were sedated with 0.5% isoflurane in oxygen and preferred it to both placebo and nitrous oxide in oxygen. It produced good operating conditions with cooperative patients and had no significant effect on vital signs. There were no significant intra- or postoperative adverse effects. Patients were street fit within 10 minutes after the end of the operation.

Intermediate bone grafting of alveolar clefts.

During the five year period 1980 to 1985 bone grafting was performed in 37 cleft patients before the eruption of the canine tooth (group IBG) and in 30 patients after the eruption of the canine tooth (group SGB). The initial healing was more favourable in the IBG group. In 72.5% of the clefts oro-nasal fistulae were present preoperatively. In all cases the fistulae were successfully closed. In the IBG group with orthodontic closure of the gap in the dental arch the interdental bone height in the grafted area was more than 75% of normal bone height in all clefts. In group SBG this situation was found in only 66% of the bone-grafted areas. There seems to be a clear relation between the age or the developmental stage of the canine tooth on the one hand and the possibility of orthodontic closure of the gap in the dental arch and good interdental bone height on the other hand. This also leads to the suggestion that if bone grafting to the alveolar cleft is required the operation should be performed before the eruption of the canine tooth on the cleft side.

Comparison between lidocaine and bupivacaine as local anesthetics with diflunisal for postoperative pain control after lower third molar surgery.

The effect of lidocaine and bupivacaine on postoperative pain were compared in a double blind crossover study. Diflunisal (500 mg) was used as an analgesic and given before commencement of the surgical procedure.Bilateral impactions of lower third molars were removed on two occasions, four weeks apart, in a sample of 26 Chinese patients. One local anesthetic was used on one occasion and the alternate on the second. Pain intensity was indicated on a visual analogue scale hourly for eight hours, beginning one hour after the start of surgery.Pain at each postoperative hour was lower after bupivacaine and more patients indicated little or no pain after bupivacaine than after lidocaine. This was not reflected in patients' preference: 12 preferring lidocaine, 11 bupivacaine, and 3 indicating no preference, an important reason being a shorter period of numbness with lidocaine.Although diflunisal was given preoperatively, the postoperative course was not complicated by alveolitis in any case.While bupivacaine plus diflunisal resulted in less postoperative pain than lidocaine plus diflunisal, some patients were willing to sustain some pain after oral surgery if sensation was regained sooner.

Paracetamol and diflunisal for pain relief following third molar surgery in Hong Kong Chinese.

In a double blind study in Hong Kong Chinese, 250 mg of diflunisal, 500 mg of paracetamol or placebo were given for post-operative pain relief following 77 third molar surgical procedures. The intensity of pain was recorded on a visual analogue scale. The first and second doses of paracetamol reduced pain significantly more than placebo, while this was true only for the second dose of diflunisal. There was no significant difference in pain reduction with the first and second dose of paracetamol, when compared with the first and the second dose of diflunisal. In this study in Hong Kong Chinese, neither the dose nor the interval between ingestion of the analgesic tablets in patients, who needed analgesics for postoperative pain, were significantly different to that reported before in non-Chinese, in contrast to the popular belief that Chinese patients have higher pain thresholds. However, a higher proportion of Chinese than that reported in non-Chinese did not need any analgesics for relief of postoperative pain.

The effect of Ro15-1788 (Anexate) on conscious sedation produced with midazolam.

A double-blind cross-over randomised study was performed to investigate whether Ro15-1788 (Anexate) adequately reversed the conscious sedation with midazolam so that patients were clinically recovered and fit for discharge quicker than when midazolam was used alone. Twenty-eight healthy patients between 18 and 34 years sedated with midazolam for bilateral 3rd molar surgery, one side being operated on at each visit. Ro15-1788 or normal saline (placebo) was given at the end of the surgical procedure at the first visit and the alternative at the second visit. Recovery with Ro15-1788 was significantly quicker than with the placebo, both by subjective (86%) and objective (93%) evaluation. Patients' evaluation indicated that only 61% were more alert at home with Ro15-1788. Postoperative adverse effects were similar in both groups.