Effect of systemic parathyroid hormone (1-34) and a beta-tricalcium phosphate biomaterial on local bone formation in a critical-size rat calvarial defect model.

OBJECTIVE: The objective of this study was to evaluate local bone formation following systemic administration of parathyroid hormone (1-34) (PTH), a surgically implanted synthetic beta-tricalcium phosphate (beta-TCP) bone biomaterial serving as a matrix to support new bone formation. MATERIALS AND METHODS: Critical-size, 8 mm, calvarial through-and-through osteotomy defects were surgically created in 100 adult male Sprague-Dawley rats. The animals were randomized into five groups of 20 animals each to receive one of the following treatments: PTH (15 microg PTH/kg/day; subcutaneously), PTH/beta-TCP, beta-TCP, or particulate human demineralized freeze-dried bone (DFDB), and sham-surgery controls. Ten animals/group were euthanized at 4 and 8 weeks post-surgery for radiographic and histometric analysis. RESULTS: The histometric analysis showed that systemic PTH significantly enhanced local bone formation, bone fill averaging (+/-SE) 32.2+/-4.0% compared with PTH/beta-TCP (15.7+/-2.4%), beta-TCP (12.5+/-2.3%), DFDB (14.5+/-2.3%), and sham-surgery control (10.0+/-1.5%) at 4 weeks (p<0.014). Systemic PTH showed significantly enhanced bone formation (41.5+/-4.0%) compared with PTH/beta-TCP (22.4+/-3.0%), beta-TCP (21.3+/-4.4%), and with the sham-surgery control (23.8+/-4.2%) at 8 weeks (p<0.025). The DFDB group showed significantly increased bone formation from 4 (14.5+/-2.3%) to 8 weeks (32.0+/-3.2%) (p<0.006). The PTH/beta-TCP and beta-TCP groups both showed limited biomaterials resorption. The radiographic analysis was not diagnostic to distinguish local bone formation from the radiopaque beta-TCP biomaterial. CONCLUSIONS: Systemic administration of PTH significantly stimulates local bone formation. Bone formation was significantly limited by the beta-TCP biomaterial.

Influence of matrix-suspended demineralized bone on osseous repair using a critical-sized defect in the rat (Rattus norvegicus) calvarium.

Demineralized freeze-dried bone (DFDB) in matrix form must be rehydrated with a carrier medium which allows for easy manipulation during periodontal surgery. The purpose of this study was to evaluate how human DFDB suspended in a polyol matrix affects new bone formation in the rat calvarium critical-sized defect (CSD) model. Fifty-five adult male Harlan Sprague-Dawley rats were assigned to 1 of 5 treatment groups: polyol, 100% DFDB, 47% DFDB/polyol, 47% DFDB, or an unfilled control. They were then placed into 8-m calvarial CSDs. The bone donor source company for the DFDB and DFDB/polyol groups was the same. Calvaria were harvested 10 weeks after surgery and evaluated histomorphometrically. The diameter of bone particles from the 3 groups containing DFDB was measured by scanning electron microscopy. There was no statistically significant difference in the percentage of bone fill between any of the groups, although the 100% DFDB group exhibited the most bone fill. The 47% DFDB/polyol and 47% DFDB groups had similar amounts of bone formation. The average size of the demineralized bone particles from the 100% DFDB group was significantly smaller than that of the other 2 groups containing DFDB. Adding a polyol to DFDB produced similar osseous regeneration in the rat calvarium defect model vs DFDB alone. Yet from a clinical standpoint, the polyol enhanced graft handling and stability. Graft particle size may have an effect on bone fill.

Gingival recession treatment with connective tissue grafts in smokers and non-smokers.

BACKGROUND: Cigarette smoking can adversely affect the results of many periodontal procedures. The purpose of this study was to determine whether cigarette smoking affects wound healing of subepithelial connective tissue grafts. METHODS: Seventeen systemically healthy patients with 22 Miller Class I or II mucogingival defects were divided into a non-smoker group or smoker group. Patients were regarded as smokers if they reported smoking 10 to 20 cigarettes per day. The following parameters were documented at the surgery date and 3 and 6 months postoperatively: recession depth (RD), recession width (RW), keratinized gingiva height measured apico-coronally (KG), relative attachment level (RAL), probing depths (PD), bleeding on probing (BOP), and the full-mouth plaque score (FMP). Salivary cotinine samples were taken at the surgery to confirm the smoking history and to quantify cigarette use. RESULTS: Non-smokers (0- to 10-ng/ml cotinine level) healed with statistically more recession coverage than the smokers (>10-ng/ml cotinine level) (98.3% versus 82.3%, respectively; P=0.001). Six months postoperatively, the non-smokers healed with a 0.2-mm mean recession depth compared to a 1.0-mm mean recession depth for the smokers. This difference in recession depth was statistically significant (P=0.014). CONCLUSIONS: Root coverage with connective tissue grafts appears to be negatively associated with cigarette smoking. Smokers should consider smoking cessation or reducing the use of cigarettes for optimal results with connective tissue grafts.

Effect of a hydroxyapatite tricalcium phosphate alloplast on osseous repair in the rat calvarium.

BACKGROUND: Bony defects caused by periodontitis are often treated by regenerative therapy using autografts and/or allografts. Alloplasts, such as hydroxyapatite or ceramics, are also used as osteoconductive materials that serve as a scaffold for new bony ingrowth. The purpose of this study was to determine the effect of hydroxyapatite tricalcium phosphate (HA-TCP) on osseous repair in the rat calvarium. METHODS: Forty-four adult male Harlan Sprague-Dawley rats were assigned to one of four treatment groups: HA-TCP macroporous disk, HA-TCP microporous disk, HA-TCP granules, and demineralized freeze-dried bone (DFDB). The materials were placed into 8-mm calvarial critical-size defects (CSD). Calvariae were harvested at 10 weeks post-surgery and evaluated histomorphometrically. RESULTS: The DFDB group had significantly (P <0.05) more new bone formation (47%) than any other group. The HA-TCP macroporous disk group had significantly (P <0.05) more new bone formation (19.7%) than the HA-TCP microporous disk (8.5%) or HA-TCP granule (6.9%) groups. CONCLUSIONS: The HA-TCP macroporous disk may elicit significant new bone formation due to its rigid space-maintaining scaffold and pore size for vascular ingrowth. It is well tolerated by host tissues and may be a suitable carrier for growth factors.

Perioral angioedema associated with angiotensin-converting enzyme inhibitor.

BACKGROUND: Angioedema is a non-pruritic swelling usually limited to the skin and mucous membranes of the face and perioral soft tissues. It can be life threatening but usually is not, and can be managed with conservative medical treatment unless the airway is endangered. Recent reports suggest that angiotensin-converting enzyme (ACE) inhibitors can predispose and/or precipitate angioedema, with a predilection toward patients of African American ancestry. METHODS: This case report involved a 65-year-old African American female who was being treated surgically for localized chronic periodontitis. The procedure was performed without incident, and the patient was alert and stable when released. The next day, the patient called and reported that her lips were swollen. She stated that this had happened a number of times over the past several years, sometimes related to eating shellfish and other times without any known precipitating factor. All previous episodes of perioral swelling occurred after ACE inhibitor therapy had been initiated. RESULTS: The patient was in no distress, with no other site involvement. She was prescribed oral hydroxyzine and her appearance returned to normal after 5 days. Although the patient had experienced previous episodes of angioedema, none had been in response to any dental procedure. She was referred to the Allergy and Immunology Clinic for skin testing, the results of which were negative to shellfish with good controls. Other potentiating etiologies were also ruled out by the allergist. CONCLUSIONS: Angioedema is a recognized possible side effect of ACE inhibitor therapy. The exact mechanism by which ACE inhibitors induce angioedema is not known, although the risk of occurrence is much greater in African Americans. Practitioners should be alert to this potentially fatal condition in patients who take ACE inhibitors or the newer angiotensin II receptor blockers (ARBs).

Severe localized periodontal destruction associated with cervical cemental separation.

Cemental separations and tears are secondary etiological factors that may lead to rapid periodontal destruction if the lesion communicates with the oral cavity and allows bacterial invasion. Although many cemental tears that occur on proximal surfaces can be diagnosed radiographically, separations on the facial or lingual surface that cannot be detected on radiographs may present a diagnostic dilemma. This article describes a case of lingual cemental separation on a maxillary incisor, with subsequent successful surgical correction utilizing an osseous graft.

In vitro study of the adverse effect of nicotine and physical strain on human gingival fibroblasts as a model of the healing of wounds commonly found in the military.

BACKGROUND: Significant adverse effects on fibroblast growth and metabolism are observed with nicotine. We investigated the synergistic effects of nicotine and cyclical mechanical strain (CMS) on human gingival fibroblasts (HGFs) in a wound-healing model. METHODS: HGFs were isolated and grown in Dulbecco's modified Eagle's medium. Three-millimeter wounds were created on a confluent cell monolayer grown in a media containing 0, 1, 2, or 4 mM nicotine, with or without CMS. The applied deformation regimen remains constant for 6 days. On days 1, 2, 4, and 6, the cells were stained with hematoxylin and eosin Y for the evaluation of wound repopulation. RESULTS: The application of CMS alone demonstrates a biphasic response, with an initial stimulatory effect on wound repopulation (days 1-2) and less repopulation during the later phase (days 4-6). The addition of nicotine clearly demonstrated a time and inverse dose-dependent relationship on wound repopulation, with no effect during the early phase and reduced wound repopulation during the later phase. CONCLUSIONS: Initial treatment of HGF wounds with CMS resulted in faster wound repopulation regardless of nicotine presence. By day 6, wound healing of HGF exposed to both nicotine and CMS is delayed. These findings suggest that CMS and nicotine may affect fibroblasts and delay wound healing at other sites in the body as well.

External root resorption following partial-thickness connective tissue graft placement: a case report.

We report an unusual case of external root resorption (ERR) that developed in a 37-year-old black male approximately 1 year following routine partial thickness connective tissue graft surgery. The lesion was accessed via flap surgery, thoroughly root planed, and the mucoperiosteal flap replaced. The site healed uneventfully and the patient has been closely observed for over 1 year without symptoms or recurrence of the resorptive lesion and the affected tooth remained vital. Clinicians performing partial-thickness connective tissue grafts should be alert to the possible occurrence of root resorption over extended periods of time. The authors speculate that retention of the donor periosteum with placement on the recipient dentin and root biomodification may limit the resorptive response following connective tissue graft procedures to treat tooth root recession.

The effects of enamel matrix derivative and cyclic mechanical strain on human gingival fibroblasts in an in vitro defect healing model.

Gingival fibroblasts (GFs) play a considerable role in the maintenance of the gingival apparatus as well as in connective tissue repair. Mobility of a periodontal wound or soft tissue graft can impair connective tissue healing from the GFs. Enamel matrix derivative (EMD) is an enamel matrix protein used clinically for periodontal regeneration of intrabony defects and furcations, as well as treatment of gingival margin recessions. The goal of this project was to compare the effects of varying concentrations of EMD, with and without cyclic mechanical strain, on cellular wound fill of human GFs using an in vitro defect healing model. GFs were seeded and cultured in six-well flexible-bottomed plates. A 3-mm wound was created in the central portion of each confluent well. Three wells were treated with each EMD concentration of 0 Μg/mL (control), 30 Μg/mL, 60 Μg/mL, or 120 Μg/mL. The plates were placed in an incubator containing a strain unit to subject test plates to cyclic strain. An identical set of control plates were not flexed. Cells were examined on days 4, 8, 12, and 16. Microphotographs were taken and wound fill measurements made using image analysis software. The percent wound fill was calculated. All nonflexed plates, regardless of EMD concentration, reached > 90% defect fill at similar rates by day 16. However, in the flexed plates, EMD had a significant negative effect on defect fill. The defect fill was 55.7% for 0 Μg/mL EMD, 48.2% for 30 Μg/mL EMD, 36.7% for 60 Μg/mL EMD, and 34.1% for 120 Μg/mL EMD on day 16 for the flexed GFs. EMD, in concentrations as high as 120 Μg/mL, did not significantly affect the amount of defect fill with nonflexed GFs. However, when the GFs were flexed, the addition of EMD had a significant negative effect on defect fill in a dose-dependent manner.

Pyogenic granuloma occurring in a postmenopausal woman on hormone replacement therapy.

Pyogenic granuloma is a benign nodular lesion occurring most commonly on the gingiva of females during periods of elevated sex hormones such as puberty and pregnancy. Possible molecular mechanisms responsible for the appearance of pyogenic granuloma in this demographic have been suggested. Increased incidence of pyogenic granuloma in post menopausal women on hormone replacement therapy has not been reported. A 49-year-old woman with preexisting titanium implant placement in the left posterior mandible presented with complaint of food impaction and slight discomfort associated with the implant. Clinical examination revealed slight soft tissue erythema and edema, but no foreign body could be identified. Subsequently, a nodular gingival lesion associated with the implant developed and was treated by conservative surgical excision. Histologic characteristics of the lesion were consistent with pyogenic granuloma. The patient was informed of the diagnosis. No evidence of recurrence could be identified after 6 months. Like peripubertal and pregnant women, postmenopausal women treated with hormone replacement therapy may be at increased risk for pyogenic granuloma. Observational studies designed to establish an association between hormone replacement therapy and pyogenic granuloma have not been conducted. Dentists should be aware of putative pathophysiologic mechanisms for pyogenic granuloma formation and the possibility that hormone replacement may trigger these mechanisms.