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Purpose: Involvement of the central nervous system in sensory disturbances of the mental region occurring after inferior alveolar nerve damage was investigated using a rat model of inferior alveolar nerve damage., Patients and Methods: The rat inferior alveolar nerve was damaged by ligation with thread, and the course of behavioral changes after surgery was observed for 42 days. In addition, activation of microglia and astroglia in the trigeminal spinal subnucleus caudalis (Vc) was analyzed using immunohistochemistry. c-Fos-positive cells were quantitatively evaluated to analyze the state of neuron excitement., Results: The withdrawal threshold was significantly decreased 5 days after surgery in the inferior alveolar nerve-ligated (IANL) group compared with that in the sham group and subsequently recovered over time. In addition, microglia and astroglia were activated in the Vc region 5 days after surgery in the model group, and c-fos-positive cells were also significantly more frequent in the IANL group. However, no significant difference in the withdrawal threshold was seen between the IANL and sham groups on day 42, nor were any significant differences seen in the amounts of microglia, astroglia, or c-fos-positive cells., Conclusions: Interactions among microglia, astroglia, and neurons in the central nervous system might be involved in the progression of inferior alveolar nerve damage-associated mental hyperalgesia to a chronic state., (Copyright © 2018 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Phyllodes tumor is a rare breast tumor described by Müller (1938) as a lesion comprising leaflike stromal fibrous components and narrow cysts. The frequency of distant metastasis from this entity is reportedly approximately 20%, and no effective therapy has been established, so the prognosis is poor. This report describes the case of a 60-year-old woman with a history of left lung resection who showed metastasis of a mammary gland malignant phyllodes tumor to the oral cavity. Intraoral examination showed an elastic, hard mass measuring 28 × 27 mm in the gingiva around the left mandibular second molar. Biopsy examination showed growth of giant cells and roughly circular cells showing positivity for S-100, p63, and vimentin on immunohistochemical staining. The authors diagnosed metastasis of the mammary gland malignant phyllodes tumor to the left mandible and performed cyber knife irradiation (44 Gy in 5 fractions) of the left mandible. The mass in the oral cavity disappeared after cyber knife irradiation, but the patient died of direct invasion to the spine., (Copyright © 2016 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: This study investigated the effect of parathyroid hormone (1-34) [PTH(1-34)] on bone reactions after tibial placement of titanium screw implants into ovariectomized rats., Materials and Methods: Twelve-week-old female Wistar rats were divided into 3 groups of 24. The first group (Sham group) was sham-operated; the second group (OVX group) was ovariectomized only; and the third group (PTH group) was subcutaneously administered 30 microg/kg PTH in the dorsal region 3 days per week starting the fourth week after ovariectomy until the end of the experiment. Titanium screw implants were placed in the proximal metaphysis of the tibia of all 3 groups at 168 days after surgery. The animals were killed 7, 14, 28, and 56 days after implantation. Undecalcified sections were prepared and evaluated by light microscopy. Histomorphometric measurements were obtained using a computer-based image analyzer to quantify the unit bone mass around the implant and the rate of implant-bone contact., Results: When PTH administration was started 21 days after ovariectomy, the volume density of bone around implants in the PTH group was almost the same as that of the Sham group throughout the entire observation period. This finding suggests that not only can intermittent human PTH(1-34) administration prevent resorption of newly generated trabeculae around an implant but also it can aid in the recovery of bone volume lost due to ovariectomy., Conclusion: When dental implants are applied to jaw bone showing trabecular bone loss, it may be possible to increase bone density around an implant by intermittent human PTH(1-34) administration and thereby improve clinical results., (Copyright 2003 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 61:471-480, 2003)

Purpose: The purpose of this study was to examine the effects of estrogen deficiency on bone remodeling adjacent to implants in the tibia of mature rats., Materials and Methods: Hydroxyapatite-coated implants were placed bilaterally in the proximal metaphysis of the tibia of 18 female Wistar rats (48 weeks old), and ovariectomy was performed 168 days later. As a control, sham ovariectomy was performed in a similar group of 18 rats. Six animals from each group were killed at 28, 84, and 168 days after ovariectomy. Undecalcified sections were prepared, and changes in the bone tissue around the implants were evaluated histologically. Histomorphometric measurements were made with a computer-based image analyzer to quantify the unit bone mass around each implant and the amount of implant-bone contact., Results: In the cortical bone area, ovariectomy induced only a slight decrease in bone contact with the implant, compared with that in the sham-operated rats. However, both the bone volume around the implant and implant-bone contact were significantly decreased in the cancellous bone area in ovariectomized rats compared with the sham-operated rats., Conclusion: Thinning of the bone trabeculae holding dental implants may occur with estrogen deficiency.

Purpose: Patterns of healing were investigated in mandibles reconstructed with three different techniques to assess their readiness for implant placement., Patients and Methods: The subjects were 10 patients who had undergone mandibular reconstruction with either nonvascularized iliac block bone grafts (group 1; 3 patients), particulate cancellous bone and marrow (PCBM) grafts (group 2; 3 patients) for mandibular discontinuity, or PCBM grafts for mandibular marginal defects (group 3; 4 patients). Six (groups 2 and 3) or 12 months (group 1) after mandibular reconstruction, bone biopsy specimens were obtained for histologic examination with a trephine bur. As controls, bone specimens were obtained from ungrafted mandibles of patients undergoing dental implant placement. Undecalcified specimens were embedded in polyester resin and examined by routine light microscopy and microradiography., Results: The morphology of the specimens from group 1 was similar to that of group 2, but not to that of the control subjects. However, the morphology of specimens from group 3 was generally similar to that of control subjects., Conclusion: These results suggest that mandibular reconstruction with PCBM grafts allows the placement of dental implants sooner than reconstruction with block bone grafts.

Purpose: The study evaluated the processes of incorporation and bone remodeling after microsurgical transplantation of iliac crest grafts for mandibular defect reconstruction., Materials and Methods: A defect in the mandibular angle measuring 2 x 4 x 1 cm was reconstructed in six Göttingen minipigs with a microvascularized iliac bone graft based on the circumflex artery. The animals were killed at 14, 28, and 56 days after transplantation and the healing process was histologically examined., Results: Although a constant vascular supply to the graft was restored by the microvascular reanastomosis, necrosis occurred in the major part of the bone marrow. New bone formation from the graft was markedly delayed compared with that from the mandible. Some osteocytes and marrow survived after grafting, but the volume of iliac bone tended to decrease gradually over time. In the 56-day specimens, the border between the graft and the mandible was not clear., Conclusion: These findings indicate that survival of the vascularized iliac bone graft in the minipig is not complete.

The purpose of this study was to investigate the effect of aging on the healing process after insertion of a hydroxylapatite (HA) implant into bone. Three groups of eight male Wistar rats, aged 6 weeks (young group), 12 weeks (adult group), and approximately 2 years (old group) were used in this experiment. Two implants were placed into the tibia of each rat. The animals were killed 7, 14, 28, and 56 days after implantation, and 15-microns, hematoxylin-eosin-stained, undecalcified sections were prepared. The healing process was examined histologically, and histomorphometric measurements were made by a computer-based image analyzer to quantify the percentage of HA-bone contact and trabecular bone in the medullary cavity. In the young group, new trabecular bone formed actively around the HA implant and good HA-bone contact was achieved more rapidly than in the adult group. In the old group, both the quantity of newly formed trabecular bone around the implant and the extent of HA-bone contact were less than in the other groups. The results suggest that the rate and volume of new bone formation around implants decrease with increasing age.

The purpose of this study was to evaluate the use of hydroxylapatite implants (HA) with autogenous bone grafts for jaw reconstruction. After autogenous iliac bone grafts were transplanted to 36 rabbit mandibles, an HA implant was installed into the graft immediately (IM group), or 90 days (90D group), or 180 days (180D group) later. The animals were killed 7, 14, 30, 60, 90, and 180 days after the HA implant placement. The healing process was examined histologically, and histomorphometric measurements were made with a computer-based image analyzer to quantify the percentage of HA-bone bonding and trabecular bone in the medullary cavity. In the IM group, the HA-bone bonding tended to be deterred by fibrous tissue, and the rate of HA-bone bonding (BBSR) was less than that of the other groups. The trabecular bone around the implants tended to decrease after 30 days in all groups. However, the average of the trabecular bone specific volume (tVsp) in the 90D group was about 10% higher than that in the other groups. From these results, it is concluded that in clinical use of HA-coated dental implants with autogenous bone grafts, the time of installation should not be immediately after the bone graft, but when there is sufficient newly formed trabecular bone to enhance HA-bone bonding.