Treatment of ligature-induced peri-implantitis by lethal photosensitization and guided bone regeneration: A preliminary histologic study in dogs

Background: the purpose of this pilot study was to evaluate the healing potential and reosseointegration in ligature-induced peri-implantitis defects adjacent to various dental implant surfaces following lethal photosensitization.Methods: A total of 36 dental implants with 4 different surface coatings (9 commercially pure titanium surface [CPTi]; 9 titanium plasma-sprayed [TPS]; 9 hydroxyapatite [HA]; and 9 acid-etched [AE]) were inserted in 6 male mongrel dogs 3 months after extraction of mandibular premolars. After a 2-month period of ligature-induced peri-implantitis and 12 months of natural peri-implantitis progression, only 19 dental implants remained. The dogs underwent surgical debridement of the remaining dental implant sites and lethal photosensitization by combination of toluidine blue O (100 mug/ml) and irradiation with diode laser. All exposed dental implant surfaces and bone craters were meticulously cleaned by mechanical means, submitted to photodynamic therapy, and guided bone regeneration (GBR) using expanded polytetrafluoroethylene (ePTFE) membranes. Five months later, biopsies of the implant sites were dissected and prepared for ground sectioning and analysis.Results: the percentage of bone fill was HA: 48.28 +/- 15.00; TPS: 39.54 +/- 12.34; AE: 26.88 +/- 22.16; and CPTi: 26.70 +/- 16.50. The percentage of reosseointegration was TPS: 25.25 +/- 11.96; CPTi: 24.91 +/- 17.78; AE: 17.30 +/- 15.41; and HA: 15.83 +/- 9.64.Conclusion: These data suggest that lethal photosensitization may have potential in the treatment of peri-implantitis.

Effect of calcitonin on bone regeneration in male rats: a histomorphometric analysis

The aim of this study was to evaluate the effectiveness of calcitonin in promoting bone growth in surgical bone defects in rat mandibles. Fifty male rats were divided into two groups: bone defect (control) and bone defect with calcitonin (experimental). A circular bone defect 4 mm in diameter was made in the mandibular bone of the rats in the angle region, and covered with a polytetrafluoroethylene barrier. The experimental group received 2 IU/kg of synthetic salmon calcitonin intramuscularly three times a week, with treatment starting immediately after surgery. The animals were killed 3, 7, 14, 21 and 28 days after the surgical procedure. The bone defects were examined histologically and by histomorphometric analysis. The Student t-test was applied to the histomorphometric data, with the level of significance set at 5%. The animals of the experimental group showed a lower level of bone formation at almost all time points than the control group, but no difference between groups was observed 28 days after surgery. The volume of newly formed bone matrix was significantly greater in the control than the experimental group at 7, 14 and 21 days, as determined by both morphologic and histomorphometric analysis. Bone repair in the calcitonin-treated animals was delayed in comparison to controls, indicating the need for further studies on male rats.

Bone regeneration at implants placed into extraction sockets of maxillary incisors in dogs

AimTo compare the influence of autologous or deproteinized bovine bone mineral as grafting material on healing of buccal dehiscence defects at implants installed immediately into the maxillary second incisor extraction socket in dogs.Material and methodsIn the maxillary second incisor sockets of 12 Labrador dogs, implants were installed immediately following tooth extraction. A standardized buccal defect was created and autologous bone particles or deproteinized bovine bone mineral were used to fill the defects. A collagen membrane was placed to cover the graft material, and the flaps were sutured to fully submerge the experimental areas. Six animals were sacrificed after 2 months, and six after 4 months of healing. Ground sections were obtained for histological evaluation.ResultsAfter 2 months of healing, all implants were osseointegrated. All buccal dehiscence defects were completely filled after 2 months irrespective of the augmentation material (autologous bone or Bio-Oss (R)) applied. Bone-to-implant contact (BIC) on the denuded implant surfaces was within a normal range of 30-40%. However, the newly formed tissue at 2 months was partially resorbed (> 50% of the area measurements) after 4 months.ConclusionsApplying either autologous bone or deproteinized bovine bone mineral to dehiscences at implants installed immediately into extraction sockets resulted in high degree of regeneration of the defects with satisfactory BIC on the denuded implant surface.To cite this article:De Santis E, Botticelli D, Pantani F, Pereira FP, Beolchini M, Lang NP. Bone regeneration at implants placed into extraction sockets of maxillary incisors in dogs.Clin. Oral Impl. Res. 22, 2011; 430-437.

Early Pancreas Transplant Improves Motor Nerve Conduction in Alloxan-Induced Diabetic Rats

The purpose of this study was to assess the temporal relationship between pancreas transplant and the development of electrophysiological changes in the sciatic and caudal nerves of alloxan-induced diabetic rats. Nerve conduction studies were performed in diabetic rats subjected to pancreas transplantation at 4, 12, and 24 weeks after diabetes onset, using nondiabetic and untreated diabetic rats as controls. Nerve conduction data were significantly altered in untreated diabetic control rats up to 48 weeks of follow-up in all time points. Rats subjected to pancreas transplantation up to 4 and 12 weeks after diabetes onset had significantly increased motor nerve conduction velocity with improvement of wave amplitude, distal latency, and temporal dispersion of compound muscle action potential in all follow-up periods (P<0.05); these parameters remained abnormal when pancreas transplantation were performed late at 24 weeks. Our results suggest that early pancreas transplant (at 4-12 weeks) may be effective in controlling diabetic neuropathy in this in vivo model.

Inferior alveolar nerve transposition with involvement of the mental foramen for implant placement

Inferior Alveolar Nerve (IAN) transposition is an option for prosthetic rehabilitation in cases of moderate or even severe bone reabsorption for patients that do not tolerate removable dentures. The aim of the present report is to describe an inferior alveolar nerve transposition with involvement of the mental foramen for implant placement. The surgical procedure was performed under local anesthesia, by the inferior alveolar, lingual and buccal nerve blocking technique. Centripetal osteotomy was performed, and bone tissue was removed, leaving the nerve tissue free in the foramen area. After that, transsection of the incisor nerve was performed, and lateral osteotomy was started from the buccal direction, toward the trajectory of the IAN. The procedure was concluded, by making use of a delicate resin spatula to manipulate the vascular-nervous bundle. The drilling sequence for placing the dental implants was performed, and autogenous bone was harvested using a bone collector attached to the surgical suction appliance. After the implants were placed, the bone tissue previously collected during the osteotomies and drilling processes was placed in order to protect the IAN from contact with the implants. The surgical protocol for inferior alveolar nerve transposition, followed by implant placement presented excellent results, with complete recovery of the sensitivity, seven months after the surgical procedure.

Nerve grafts prevent paraplegic pressure ulcers

We present an optimistic neural solution to the depressing challenge of decubitus pressure ulcers in the paraplegic patient. This is a limited study of two paraplegic men followed for several years. Sural nerve grafts, performed end-to-side, successfully bridged the sciatic nerve to intercostal nerves with surprising benefits for both men.

Guanidine Affects Differentially the Twitch Response of Diaphragm, Extensor Digitorum Longus and Soleus Nerve-Muscle Preparations of Mice

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Clinical significance of supplementary innervation of the lower incisor teeth: a dissection study of the myelohyoid nerve

In view of the relevance of the mylohyoid nerve to clinical difficulties in achieving deep analgesia of the lower incisors, a dissection study was undertaken. Dissections from 29 adult cadavers of both sexes were studied with the aid of a dissecting microscope. The following observations were made: a supplementary branch of the mylohyoid nerve entered the mandible through accessory foramina in the lingual side of the mandibular symphysis in 50% of the cases; it generrally arose from the right side (76.9%) and entered the inferior retromental foramen (84.6%); the mylohyoid nerve branch either ended directly in the incisor teeth and the gingiva or joined the ipsilateral or contralateral incisive nerve. In view of this information concerning the high incidence of possible involvement of the mylohyoid nerve in mandibular sensory innervation, it is advisable to block it whenever intervention in the lower incisors is indicated. Routine mylohyoid injection is recommended after mental nerve block. If the inferior alveolar nerve is chosen for anesthetic purposes, additional mylohyoid injection should be given only if pain persists. The mylohyoid injection should be given at the inferior retromental foramen on the median aspect of the inferior border of the mandible through extraoral approach.