Regenerative materials: an overview

Periodontal reconstructive therapies have demonstrated the ability to reverse the destruction due to periodontitis provided that they are implemented according to their individual indications. By properly evaluating a site, one can employ an evidence-based approach to effectively and predictably treat intrabony defects and furcation involvements. It also should be emphasized that a thorough evaluation of the therapeutic outcome should be continuously performed on all sites in order to determine treatment success and the possible need for further intervention. This is based on the long-term follow-up of cases treated with regenerative therapies, which have shown maintenance of results if the patient had good oral hygiene and was enrolled in a proper maintenance program. With respect to the preceding discussion: 1. The main periodontal reconstructive therapies employed by periodontists are GTR, bone replacement grafts and biologic mediators. 2. It is possible to achieve regeneration when using barriers, autografts, allografts, bovine-derived xenografts and EMDs. 3. Currently, regenerative techniques can be used for the treatment of intrabony defects and furcation involvements given the proper evaluation of each individual site. 4. Various regenerative materials are capable of achieving similar results in intrabony defects and are very predictable when employing evidence-based treatment. 5. A combination of regenerative materials such as barriers and grafts in intrabony defects has not demonstrated any improvement over their use alone. 6. A combination of regenerative materials such as barriers and grafts in mandibular class II furcations has demonstrated improvement over the use of the graft or barrier alone. 7. A combination of regenerative materials such as barriers and grafts in maxillary class II furcations has some limited evidence to support improvement over the use of the graft or barrier alone, but the predictability should not be considered high. 8. A combination of regenerative materials such as barriers and grafts in class III furcations has very limited evidence to support improvement over the use of the graft or barrier alone and should not be considered predictable. 9. Beyond the initial healing phase postsurgically, maintenance and oral hygiene play the largest role in long-term therapeutic success.

Parathyroid hormone-related protein regulates extracellular matrix gene expression in cementoblasts and inhibits cementoblast-mediated mineralization in vitro

Parathyroid hormone-related protein (PTHrP) has been implicated in regulating tooth eruption and/or development. Formation of cementum, a mineralized tissue covering the tooth root surface, is a critical biological event for tooth root development. To test the hypothesis that PTHrP targets cementoblasts (CMs) and acts to regulate cementogenesis, CM cell lines were established and their responsiveness to PTHrP stimulation was determined, in vitro. First, subclones were derived from two immortalized murine cell populations that contained CMs; SV-CM/periodontal ligament (PDL) cells were obtained from the root surface of first mandibular molars of CD-1 mice and immortalized with SV40 T-antigen (TAg), and OC-CM cell population was established from OC-TAg transgenic mice in which their cells harbor an osteocalcin (OC and/or OCN) promoter-driving immortal gene SV40 TAg. Based on our previous in situ studies, CM subclones were identified as cells expressing bone sialoprotein (BSP) and OCN transcripts, while PDL cell lines were designated as cells lacking BSP and OCN messenger RNA (mRNA). CMs exhibited a cuboidal appearance and promoted biomineralization, both in vitro and in vivo. In contrast, PDL cells (PDL subclones) displayed a spindle-shaped morphology and lacked the ability to promote mineralized nodule formation, both in vitro and in vivo. Next, using these subclones, the effect of PTHrP on cementogenesis was studied. CMs, not PDL cells, expressed PTH/PTHrP receptor mRNA and exhibited PTHrP-mediated elevation in cyclic adenosine monophosphate (cAMP) levels and c-fos gene induction. PTHrP stimulation repressed mRNA expression of BSP and OCN in CMs and blocked CM-mediated mineralization, in vitro. Collectively, these data suggest that CMs possess PTH/PTHrP receptors and, thus, are direct targets for PTHrP action during cementogenesis and that PTHrP may serve as an important regulator of cementogenesis.

Restorative considerations in the dental treatment of the older patient

The older person and his or her dentition will have a clinical presentation and a reaction to treatment that is influenced by his or her unique blend of aging and disease processes. Changes seen in enamel, dentin, pulp, and cementum of the older patient are described in terms of their causes and the impacts of the changes on clinical presentation and treatment choices.

A study of attached and oriented human periodontal ligament cells to periodontally diseased cementum and dentin after demineralizing with neutral and low pH etching solution

BACKGROUND

This study aimed to evaluate quantitatively the migrated, attached, and oriented human periodontal ligament cells (HPLC) to periodontally diseased cementum and dentin after demineralization with low and neutral pH etching solution.

METHODS

Human teeth, extracted due to periodontal diseases, were scaled and root planed so that cementum remained on one longitudinal half of the root and dentin was exposed on the other half. Forty root slices of 200 microm thickness, obtained from the mid-third of these roots, were divided into four groups: group 1, demineralized with a saturated solution of citric acid (pH 1.20); group 2, with 24% EDTA (pH 7.04); group 3, with tetracycline HCl 100 mg/ml (pH 2.00); and group 4, only scaled and root planed (control). Root slices were placed over the confluent HPLC in 35 mm culture dishes and incubated. Phase contrast microscopic photographs of attached and oriented refractile HPLC to root surfaces were taken at days 1, 3, and 7. Quantitative analysis of attached and oriented HPLC from these photographs was done using special software.

RESULTS

The results showed no significant difference in the attachment and orientation index of HPLC to cementum compared to dentin in any method of demineralization at each time point (P >0.05), although there was a significantly higher cell attachment and orientation index to demineralized dentin with EDTA and citric acid than to non-etched dentin and to all 3 demineralized cementum surfaces compared to non-etched cementum (P<0.05).

CONCLUSIONS

EDTA and citric acid demineralization may enhance HPLC attachment and orientation to the root surface, and it is not always necessary to remove excessive cementum when the demineralizing procedure is used.

Periodontal tissue regeneration in beagle dogs after laser therapy

BACKGROUND AND OBJECTIVE

Class III periodontal furcations still represent a challenge for the periodontist. Aim of this study was to test the effect of CO2 laser on the treatment of class III furcation defects. STUDY DESIGN/MATERIALS AND METHOD: Class III furcation defects 3 mm deep were surgically induced on mandibular premolars on six male Beagle dogs, for a total of 36 defects. After 6-8 weeks of plaque accumulation, the mean depth was 6.8 mm. Quadrants were randomly assigned to a) CO2 laser therapy (laser), b) Guided Tissue Regeneration (GTR) procedure using Gore-Tex Membranes, (Gore Tex, Flagstaff, Arizona, USA) and c) Scaling and Root planing (Sc/Rp). CO2 laser beam (El.En, Florence, Italy) was applied to the root surfaces in defocused pulsed mode at 2W, 1 Hz and a duty cycle of 6%, and on periodontal soft tissues at 13W, 40 Hz, and a duty cycle of 40%. Control quadrants received either GTR procedure or Sc/Rp. Mechanical oral hygiene was provided. At 6 months the animals were sacrificed.

RESULTS

The laser group showed new attachment formation averaging 1.9 mm (sd +/- 0.5), whereas GTR and Sc/Rp showed 0.2 mm (sd +/- 0.4) and 0.2 mm (sd +/- 0.5) respectively, being the differences statistically significant between the laser group and both GTR and Sc/Rp groups (p < 0.005).

CONCLUSION

CO2 laser treatment of class III furcation induced formation of new periodontal ligament, cementum and bone.

Clinical and histologic evaluation of human gingival recession treated with a subepithelial connective tissue graft and enamel matrix derivative (Emdogain): a case report

A mandibular canine with significant gingival recession was selected for a pilot study to measure the attachment modalities resulting from mucogingival surgery. The tooth had 6 mm of recession as measured from the cementoenamel junction to the gingival margin, minimal pocketing, and no keratinized gingiva. The treatment regimen consisted of a subepithelial connective tissue graft (SCTG) plus Emdogain applied to the root surface. The tooth was extracted en bloc 6 months after surgery and processed histologically in a buccolingual plane. The tooth demonstrated a 2-mm gain of attachment and a 3-mm gain in keratinized tissue. The histologic study evidenced the migration of the junctional epithelium 1.2 mm apical to the sulcus. New cementum, evidence of newly formed woven bone, and connective tissue fibers anchored in the new cementum were evident.

Differential involvement of matrix vesicles during the initial and appositional mineralization processes in bone, dentin, and cementum

The distribution of matrix vesicles and its role in biological mineralization were examined in bone and dental hard tissues of the rat after daily administrations of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP), a potent inhibitor of mineralization, for 7 or 14 days. Newly formed, nonmineralized matrices of the HEBP-affected bone and mesodermal dental hard tissues other than circumpulpal dentin contained numerous mineral-filled matrix vesicles (MV), randomly distributed throughout the collagenous matrix. The distribution density of the mineral-filled MV in the HEBP-affected matrices of calvaria, metaphyseal trabecular bone, alveolar bone, and cellular cementum ranged from 60 to 70 per 100 microm(2), and no statistically significant differences were noted among the values. In the HEBP-affected dentin, however, MV were located only in the nonmineralized matrix of mantle dentin and totally absent in the circumpulpal dentin layers. Instead, the HEBP-affected circumpulpal dentin contained a dense meshwork of noncollagenous matrix enriched with calcium and phosphorus. Comparable meshwork structures were undetectable in nonmineralized matrices of the other hard tissues affected by HEBP. These observations suggest that a certain population of MV (60-70 per 100 microm(2)) is involved in the process of appositional mineralization in most of the mesodermal hard tissues, in addition to their well-known role in initial mineral induction in these tissues. Circumpulpal dentin appears to be an exception, where MV are not required for the appositional mineralization process. Exclusive localization of dentin phosphoproteins in circumpulpal dentin layers must take place to facilitate appositional mineralization at the calcification front, in the absence of MV.

Emdogain: evidence of efficacy

This article addresses the use of enamel matrix proteins (Emdogain) to enhance regeneration of the periodontium. Information regarding the role of Emdogain to induce cementogenesis and histologic evidence in animals and humans that it can initiate regeneration of diseased sites are discussed. Several clinical trials have indicated that Emdogain plus modified Widman flap surgery provide a better result than the surgery alone. Several other investigations have indicated that flap surgery plus Emdogain or a bioabsorbable membrane achieve similar results. However, this latter finding needs further validation. Clinical examples of successful therapy with Emdogain are presented.

The effects of attachment factors on initial attachment of human periodontal ligament fibroblasts on different root surfaces: a light and scanning electron microscopic study

This study was aimed to test the effect of fibronectin (FN), vitronectin (VN) and a fibronectin analog (fibronectin-like engineered protein) on the attachment of periodontal ligament cells to mechanically-treated and mechanically non-treated periodontally involved and non-diseased root surfaces in vitro. Periodontal ligament fibroblasts were incubated with a total of 44 periodontally diseased and non-diseased root slices which had been treated in the following manner: 1) FN applied to mechanically-treated and non-treated root slices, 2) VN applied to mechanically-treated and non-treated root slices, 3) FN-like engineered protein applied to mechanically-treated and non-treated root slices, and 4) mechanically-treated and non-treated root slices. After the 1 hour incubation period in a humidified atmosphere of 95% air and 5% CO2 at 37 degrees C, the adherence of the fibroblasts was determined using light microscopy with an ocular grid system and orientation was evaluated by scanning electron microscopy. The results indicated that the number of attached cells to non-diseased cementum sites was significantly greater than the number of attached cells to diseased cementum sites for all of the groups (p < 0.05). Likewise, the number of attached cells to mechanically-treated diseased cementum sites was significantly greater than the number of attached cells to mechanically-non-treated diseased cementum sites (p < 0.05). Our findings suggest that these attachment factors cannot promote cell attachment to different cementum sites.

Guided tissue regeneration with a bioabsorbable polylactic acid membrane in gingival recessions. A histometric study in dogs

BACKGROUND

The goal of this investigation was to histologically and histometrically evaluate the healing process of gingival recessions treated by guided tissue regeneration with bioabsorbable polylactic acid membranes (GTR group) and to compare it to that obtained with coronally positioned flaps (CPF group).

METHODS

Gingival recessions were surgically created on the buccal aspect of the upper cuspids of 5 mongrel dogs. The defects (5x7 mm) were exposed to plaque accumulation for 3 months. The contralateral defects were then randomly assigned to each group. After 3 months of healing, the dogs were sacrificed and the blocks were processed. The histometric parameters evaluated included length of sulcular and junctional epithelium, connective tissue adaptation, new cementum, new bone, and defect coverage.

RESULTS

The extension of the epithelium was 1.9 +/- 0.8 mm for the GTR-group and 3.0 +/- 0.9 mm for the CPF-group (P = 0.16). The connective tissue adaptation was 0.1 +/- 0.1 and 0.8 +/- 0.5 mm in the GTR group and CPF group, respectively (P = 0.051). The new cementum was 3.8 +/- 1.5 mm and 2.4 +/- 0.3 mm in the GTR group and CPF group, respectively (P= 0.16). Bone formation was 1.1 +/- 0.5 mm in the GTR group and 1.4 +/- 0.2 mm in the CPF group (P = 0.53). Histologically, the defect coverage observed was similar, 90.5% and 91.9% for the GTR group and the CPF group, respectively. No statistical differences in any of the parameters could be detected.

CONCLUSIONS

Within the limits of this study, it can be concluded that both procedures resulted in a favorable healing response with no significant difference between the treatments.

The use of demineralized freeze-dried bone-glycoprotein matrix grafts in treating baboon periodontal infrabony defects

In an effort to improve regenerative capacity and establish higher levels of predictability, the use of a new graft material was investigated in baboon infrabony periodontal defects. A graft matrix composed of human demineralized freeze-dried bone combined with human connective tissue glycoprotein was implanted in 20 defects in 9 baboons. Control, debrided-only sites in the same animal served as a comparison. Grafted sites achieved a 1.8-mm greater reduction in probing depth and attachment gain compared to controls. In addition, 25.3% greater defect fill was found in grafted sites. Histologic analyses provided evidence of bone induction by the graft matrix and regeneration of new cementum, periodontal ligament, and bone in the grafted sites.

Employing a transgenic animal model to obtain cementoblasts in vitro

BACKGROUND

Proper formation of cementum, a mineralized tissue lining the tooth root surface, is required for development of a functional periodontal ligament. Further, the presence of healthy cementum is considered to be an important criterion for predictable restoration of periodontal tissues lost as a consequence of disease. Despite the significance of cementum to general oral health, the mechanisms controlling development and regeneration of this tissue are not well understood and research has been hampered by the lack of adequate in vitro experimental models.

METHODS

In an effort to establish cementoblast cell populations, without the trappings of a heterogeneous population containing periodontal ligament (PDL) cells, cells were obtained from the root surface of first mandibular molars of OC-TAg transgenic mice. These mice contain the SV40 large T-antigen (TAg) under control of the osteocalcin (OC) promoter. Therefore, only cells that express OC also express TAg and are immortalized in vitro. Based on results of prior in situ studies, OC is expressed by cementoblasts during root development, but not by cells within the PDL. Consequently, when populations are isolated from developing molars using collagenase/trypsin digestion, only cementoblasts, not PDL cells, are immortalized and thus, will survive in culture.

RESULTS

The resulting immortalized cementoblast population (OC/CM) expressed bone sialoprotein (BSP), osteopontin (OPN), and OC, markers selective to cells lining the root surface. These cells also expressed type I and XII collagen and type I PTH/PTHrP receptor (PTH1R). In addition to expression of genes associated with cementoblasts, OC/CM cells promoted mineral nodule formation and exhibited a PTHrP mediated cAMP response.

CONCLUSIONS

This approach for establishing cementoblasts in vitro provides a model to study cementogenesis as required to enhance our knowledge of the mechanisms controlling development, maintenance, and regeneration of periodontal tissues.

Combined treatment of a large periodontal defect using GTR and DFDBA

The regeneration of periodontal structures lost to inflammatory disease is an elusive yet attainable goal of periodontal therapy. This article reports the successful treatment of a large periodontal defect using a combination of demineralized freeze-dried bone allograft (DFDBA) and guided tissue regeneration (GTR). The case presents endodontic and mucogingival complications in the combined GTR osseous graft technique. The combined techniques used in this 27-year-old patient achieved a reduction in probing depth, radiographic evidence of bone fill, and a reduction in clinical mobility.

Effects of occlusal loading on ankylosis, bone, and cementum formation during bone morphogenetic protein-2-stimulated periodontal regeneration in vivo

BACKGROUND

The purpose of this study was to investigate the influence of occlusal loading on recombinant human bone morphogenetic protein-2 (BMP-2)-induced bone and cementum formation in a previously established rat model of periodontal regeneration during the early and late stages of wound healing.

METHODS

64 Wistar rats were divided into 8 groups and had surgically created fenestrated defects on the right side of the mandible involving the removal of bone and exposure of the first and second molar roots. Four groups had their right maxillary molars extracted 2 weeks prior to surgery. Ten microl of 100 ug/ml BMP-2 in a collagen membrane was placed in extracted (hypofunctional) and non-extracted (functional) groups (BMPe and BMPf, respectively) while control groups had collagen membrane only (CONe and CONf). Groups were sacrificed at 10 (BMPe, BMPf, CONe, CONf) or 35 days (BMP35e, BMP35f, CON35e, CON35f) postoperatively and tissues processed for histological examination. Transverse 5 microm sections were stained for identification of new bone, ankylosis and cementum formation.

RESULTS

At 10 days, CONe developed greater bone growth compared with CONf (P<0.05), while both BMP groups developed greater bone compared with controls. However, BMPe developed more ankylosis compared with both CONe and CONf while BMPf was significantly greater than CONf only (P<0.05). BMPf only developed significantly greater new cementum compared with controls. At 35 days, BMP35f developed greater bone growth compared with all other groups including BMP35e (P<0.05) and unlike results at 10 days, no differences were apparent between CON35f and CON35e. Unwanted bone growth beyond the defect margin anteriorly was significantly greater in BMP35f.

CONCLUSIONS

Results suggest hypofunction stimulates early bone formation. Furthermore, hypofunction and BMP-2 increase the development of transient ankylosis. However, after wound healing is complete, function augments the early effects of BMP-2-induced new bone growth indicating remodeling to physiological levels does not occur. Finally, occlusal loading is both an important stimulus for remodeling and establishment of the periodontal ligament space during early wound healing as well as enhancing BMP-2-induced cementogenesis.

GTR with bioresorbable membranes in the treatment of intrabony defects: a clinical and histologic study

The aim of the present study was to evaluate clinically and histologically the treatment of intrabony periodontal defects with a bioresorbable membrane barrier. Fifty-two intrabony periodontal defects were treated according to the principles of guided tissue regeneration (GTR) with a bioresorbable membrane. Results were evaluated by assessing probing pocket depth, recession of the gingival margin, and clinical attachment level at baseline and at 1 and 2 years after therapy. Bone level changes were evaluated radiographically. The postoperative phase was uneventful in all cases. There was a mean probing pocket depth reduction from 8.4 to 3.6 mm, a mean increase of gingival margin recession from 1.5 to 3.0 mm, and a mean clinical attachment level change from 9.9 to 6.5 mm. Mean attachment gain was 3.4 mm. Two teeth scheduled for extraction were also treated with the same bioresorbable membrane. The histologic analysis 6 months after treatment revealed the formation of new connective tissue attachment and new alveolar bone in both cases. Based on the histologic findings it can be concluded that the clinical improvements following GTR with this type of bioresorbable membrane may represent, at least in part, true periodontal regeneration.

Response of dental follicular cells to the exposure of denuded enamel matrix in rat molars

Recent studies have indicated that cementum formation can be induced when dental follicular cells are exposed to enamel matrix. The purpose of the present investigation was to study this cementum formation and the appearance of the cells involved, including their expression of collagen types alpha1(I), alpha1(II) and alpha1(III) mRNAs, during this process by means of light microscopy and in situ hybridisation. The mandibular first molars of 5-d-old rats were surgically taken out, their enamel epithelium was removed, and then the crowns were re-inserted with the occlusal surface downwards in their crypts to allow the follicular cells to come in contact with the denuded enamel matrix. After observation periods of 2-14 d, the teeth were prepared for light microscopic examination and in situ hybridisation. A monolayer of follicular cells in contact with the exposed enamel matrix changed their morphology and increased their expression of collagen type I mRNA as early as 2-4 d after exposure to the enamel matrix. A cementum-like tissue was formed at the surface of the enamel matrix. Collagen type II mRNA was never expressed in the tissues studied, whereas collagen type III mRNA was weakly expressed in the follicular cells throughout the experiment.

Evolution of periodontal regeneration: from the roots' point of view

Tissues lost as a consequence of periodontal diseases, i.e. bone, cementum and a functional periodontal ligament (PDL), can be restored to some degree. Nevertheless, results are often disappointing. There is a need to develop new paradigms for regenerating periodontal tissues that are based on an understanding of the cellular and molecular mechanisms regulating the development and regeneration of periodontal tissues. As one approach we have developed strategies for maintaining cementoblasts in culture by first determining the gene profile for these cells in situ. Next, cells were immortalized in vitro using SV 40 large T antigen (SV40 Tag) or by using mice containing transgenes enabling cellular immortality in vitro. Cementoblasts in vitro retained expression of genes associated with mineralized tissues, bone sialoprotein and osteocalcin, that were not linked with periodontal fibroblasts either in situ or in vitro. Further, cementoblasts promoted mineralization in vitro as measured by von Kossa and ex vivo using a severely compromised immunodeficient (SCID) mouse model. These cells responded to growth factors by eliciting changes in gene profile and mitogenesis and to osteotropic hormones by evoking changes in gene profile and ability to induce mineral nodule formation in vitro. The ultimate goal of these studies is to provide the knowledge base required for designing improved modalities for use in periodontal regenerative therapies.

Immortalized cementoblasts and periodontal ligament cells in culture

Cementum, a mineralized tissue lining the surface of the tooth root, is required for formation of a functional periodontal ligament attachment during development. Additionally, during regeneration of tissues after disease, cementum is thought to play a critical role in the reparative process. Research efforts aimed toward understanding mechanisms involved in periodontal development and regeneration, and in particular the formation of root cementum, have been hampered by an inability to isolate and culture cells involved in cementum production, i.e., cementoblasts. Using classical techniques for osteoblast isolation, immortalized, heterogeneous cementoblast/periodontal ligament cell (CM/PDL) populations were established from cells lining the tooth root surface of: 1) CD-1 mice, where cells were immortalized using SV40, or 2) H-2KbtsA58 "immorto" mice, where cells containing an immortalizing transgene were removed and cultured. CM/PDL populations were derived from tissues adherent to developing tooth root surfaces, while tissues adherent to the surrounding alveolar bone were specifically excluded from the population. Immortalized CM/PDL cells were characterized to ensure their phenotype reflected that previously demonstrated in situ and in primary, nonimmortalized cultures. Proteins/mRNAs associated with bone/cementum and known to be expressed by root lining cementoblasts, but not by PDL cells, in situ, e.g., bone sialoprotein, osteopontin, and osteocalcin, were expressed by cells within the immortalized populations. Furthermore, CM/PDL cells, in vitro, attached to bone sialoprotein in an arginine-glycineaspartic acid (RGD)-dependent manner, promoted mineral nodule formation and exhibited a PTH/PTHrP-mediated cAMP response. These immortalized heterogeneous populations, containing both CM and PDL cells, provide a unique opportunity to study cells involved in cementogenesis and to enhance our knowledge of the mechanisms controlling development, maintenance, and regeneration of periodontal tissues.

The structure and function of the cemento-dentinal junction in human teeth

The structure and function of the cemento-dentinal junction were studied in human molars by light and electron microscopy. The cemento-dentinal junction was an approximately 1-3-micron-thick layer full of proteoglycans with mucopolysaccharides but containing fewer collagen fibrils than the root dentin and cementum. In places, cemental fibrils crossed the cemento-dentinal junction. These fibrils appeared to intermingle with dentinal fibrils. By enzymatic treatment of decalcified specimen with hyaluronidase and trypsin, the cemento-dentinal junction decreased or lost staining affinity to toluidine blue. Prolonged treatment caused the separation of cementum from the root dentin during routine histological processes. These data suggest that the adhesion of proteoglycans is more important than the intermingling of dentinal and cemental fibrils for the cemento-dentinal attachment.

Periodontal repair in dogs: histologic observations of guided tissue regeneration with a prostaglandin E1 analog/methacrylate composite

This report describes observations of healing following guided tissue regeneration (GTR) including surgical implantation of the prostaglandin E1 analog misoprostol with calcium-layered methacrylate particles. Critical size, supra-alveolar periodontal defects were surgically created around the 3rd and 4th mandibular premolar teeth in 4 beagle dogs. Wound management included soaking with a 24 microg/ml misoprostol solution and implantation of the misoprostol/methacrylate composite. One jaw quadrant per animal was prepared for GTR using expanded polytetrafluoroethylene membranes. The gingival flaps were coronally advanced and sutured to submerge the teeth. The tissues covering the surgical sites daily received topical misoprostol in an oral adhesive over the 4-week healing interval. Upon euthanasia, tissue blocks were prepared for histometric analysis of regeneration of alveolar bone and cementum, root resorption and ankylosis. The defect area underneath the membrane and the density of methacrylate particles were recorded for the GTR defects. The methacrylate particles appeared encapsulated in a dense connective tissue without signs of an inflammatory reaction, some in contact to newly formed bone. Alveolar bone regeneration height averaged (+/-SD) 1.2+/-1.0 and 1.0+/-0.6 mm for GTR and non-GTR defects, respectively. Corresponding values for bone regeneration area were 1.3+/-1.0 and 0.7+/-0.5 mm2. Cementum regeneration was confined to the apical aspect of the defects. Small areas of root resorption and ankylosis were observed for all teeth. Bone regeneration area correlated positively to the defect area and negatively to the density of methacrylate particles in the GTR defects. The histologic observations suggest that the methacrylate composite has marginal potential to promote bone and cementum regeneration under provisions for GTR.

Enamel matrix derivative for periodontal reconstructive surgery: technique and clinical and histologic case report

This paper describes a step-by-step technique for the application of Emdogain, a new enamel matrix derivative (EMD) graft material, for periodontal reconstructive surgery. A case report is presented with a 1-year follow-up. The rationale for use and advantages and disadvantages of EMD are discussed. An additional human histologic case report demonstrates that the formation of new bone, cementum, and periodontal ligament is possible following the use of EMD.