Root Surfaces Of Teeth Research Articles

A strain gauge and photoelastic analysis of in vivo strain and in vitro stress distribution in human dental supporting structures

Strain gauge and photoelastic experiments have been workhorses of experimental stress analysis for over 50 years. In this study, both were used to analyse the nature of stress distribution from the tooth root surface to the supporting alveolar bone. Such studies help in understanding the behaviour of dental supporting structures under physiological function. In the strain gauge experiment, the mechanical strains were measured on the supporting bone surface and the root surface of the tooth under applied bite force. It was found that higher strains were distributed along the cervical region of the supporting bone and the root surface. The photoelastic study was also done to evaluate the stress distribution pattern from the root surface to the supporting bone under clinical conditions. The stress patterns were found to decrease from the cervical to the apical region of the root surface. These studies highlight the role of the periodontium in stress distribution and bone remodelling.

Radiographic evidence of enamel pearls in jordanian dental patients.

An "enamel pearl" is an ectopic globule of enamel that is adherent to the tooth root surface. Such an anomaly may facilitate the progression of periodontal breakdown. Information on the prevalence of enamel pearls is sparse, and ethnic variations are thought to occur. Our objective was to assess the prevalence of enamel pearls in a group of Jordanian dental patients. A random sample of 819 dental records were selected, and a total of 1032 periapical radiographs were interpreted for the presence of enamel pearls. Enamel pearls were detected in 4.76% of the subjects and on 1.6% of the molars. No significant difference between sexes was observed. First molar teeth were the most commonly affected, whereas the third molars were the least affected with the condition. Enamel pearls are not uncommon among Jordanian dental patients, and their early detection could be important in prevention of periodontal disease.

Topography of periodontally involved human root surfaces after different chemical treatment modalities: an in vitro scanning electron microscopic study.

The significance of chemical and conservative treatments of cemental tissue proximal to periodontal pockets has been pointed out in recent years. This in vitro scanning electron microscopy (SEM) study aimed to investigate the surface effects of topical applications of 0.1% cetylpyridinium chloride (CPC) and 2% sodium lauryl sulfate (SLS) and polishing on the periodontally involved root surfaces of human teeth. Ten single-rooted teeth from 8 patients with advanced adult periodontitis were included. Following extraction, any calculus was removed with extreme care to preserve as much cementum as possible. Eighty root specimens were prepared. Fresh solutions of CPC and SLS were applied for 1, 3 and 5 minutes each to 10 segments of root cementum. A total of 20 segments formed the polished (P) and control (C) groups, respectively. The results showed that the surfaces treated with CPC or SLS differed considerably from polished and control specimens. Depending on time, the surface coating was partly or wholly removed, leaving a nodular cementum structure, uncovering a fibrillar collagen substrate and the openings of dentinal tubules. Scarce debris was present on both control and polished surfaces, whereas bacteria were observed only on the control specimens. In view of these results, further definitive in vitro and in vivo research must be done to determine the advantages of chemical treatment and its effect on periodontal regeneration.

Employing a transgenic animal model to obtain cementoblasts in vitro.

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. 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. 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. 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.

The diversity and distribution of the predominant ribotypes of Actinomyces naeslundii genospecies 1 and 2 in samples from enamel and from healthy and carious root surfaces of teeth.

The bacterial communities associated with root caries are highly diverse and undergo succession during lesion formation. Consequently, root caries is said to have a polymicrobic etiology, typified by variation in the predominant species among samples from different lesions. Despite the polymicrobic etiology, A. naeslundii genospecies 1 and 2 (previously A. viscosus) have consistently been shown to be associated with root caries in humans; they predominate in some lesions and have been suggested to play a significant role in the disease. Several genetic variants of A. naeslundii are known to be present among the oral A. naeslundii population of an individual. The current study was initiated to explore the possibility that a variant in these A. naeslundii populations had characteristics which made it best fitted to colonize or promote root-surface caries lesions. Using ribotyping to detect variants, we tested the hypothesis that 'a ribotype of A. naeslundii best fitted to the environment would be selected and predominate in the A. naeslundii population of lesions'. Samples of plaque from enamel, normal root surfaces, plaque overlying the lesion, and material from within the lesion were taken from nine patients with soft root caries. The flora from 14 lesions and 9 enamel sites was analyzed on selective and non-selective media, and A. naeslundii genospecies were identified by serology. We ribotyped 972 isolates, showing 54 different patterns. Between 6 and 20 ribotypes were isolated from eight of nine patients. In general, each site from a patient showed a similar distribution of ribotypes. These results do not support the hypothesis and suggest that any phenotypic characters that allow A. naeslundii genospecies 1 and 2 to colonize or contribute to the formation of root-caries lesions are common among strains identified by ribotyping.

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-2K btsA58 “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-glycine-aspartic 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 pathobiology of periodontal diseases may affect systemic diseases: inversion of a paradigm.

A new paradigm for the pathobiology of periodontitis is presented, and the manner in which periodontitis may relate to susceptibility for certain systemic diseases such as cardiovascular disease and preterm labor is described. Periodontitis is caused by a small group of Gram-negative bacteria present on the tooth root surfaces as bioffilms. Lipopolysaccharide (LPS) and other substances gain access to the gingival tissues, initiate and perpetuate immunoinflammation, resulting in production of high levels of proinflammatory cytokines. These induce production of matrix metalloproteinases which destroy the connective tissues of the gingiva and periodontal ligament, and prostaglandins which mediate alveolar bone destruction. Periodontitis may enhance susceptibility to systemic diseases in several ways. LPS and viable Gram-negative bacteria from the biofilms and proinflammatory cytokines from the inflamed periodontal tissues may enter the circulation in pathogenic quantities. In addition, periodontitis and certain systemic diseases, such as cardiovascular disease, share risk factors including tobacco smoking, male gender, race/ethnicity, stress, and aging.

GTR treatment of degree III furcation defects following application of enamel matrix proteins. An experimental study in dogs.

The aim of the present study was to evaluate the effect of enamel matrix proteins (EMD) on periodontal wound healing in degree III furcation defects in dogs. The experiment was performed in 5 foxhound dogs. 2 months prior to the start of the experiment, the 2nd and 4th lower premolars were extracted. Degree III furcation defects were created in the 3rd mandibular premolars (3P3). The furcation defects were subsequently exposed to reconstructive surgery. Buccal and lingual full thickness flaps were elevated in the lower premolar regions. The exposed root surfaces of the experimental teeth were planed. A notch was placed in the roots at the base of the defect. In one side of the mandible (Test group), phosphoric acid gel was applied over the root surfaces for 15 s. The acid was removed by flushing the root surfaces with sterile saline. Subsequently, a gel of EMD was applied to cover all instrumented root surfaces. Following gel application, a resorbable barrier membrane was adjusted to cover the buccal and lingual entrances of the furcation defect. The flaps were repositioned to cover the barrier and sutured. The contralateral premolar (Control group) received the same treatment, but acid etching was not performed and EMD was not applied prior to barrier installation. 4 months after reconstructive surgery, the animals were sacrificed and biopsies from the 3P3 regions harvested. The biopsies were placed in a fixative, demineralized in EDTA, dehydrated and embedded in paraffin. 3 mesiodistal sections, representing the central portion of the furcation site, were selected for histological analysis of the defect. The furcation defects of both the Test and Control groups were clinically closed and were found to harbor bone and periodontal ligament tissue which appeared to be in structural continuity with a newly formed root cementum. The relative amounts of mineralized bone, bone marrow and periodontal ligament tissue that had formed were similar in the Test and the Control group. In the Test group, however, the cementum that had formed in the apical portion of the furcation defect was different from the corresponding tissue in the coronal portion, and also different from the cementum observed in the Control group. In the apical portion of the test defect a thin (12 microm) acellular cementum had been laid down, while in the coronal portion a thick (32 microm) cellular cementum, similar to the cementum found in the Control group, could be observed. The current observation, hence, seems to confirm that EMD when applied onto an instrumented and acid etched dentine surface may create an environment conducive for the formation of acellular cementum.

Anatomic characteristics of the furcation and root surfaces of molar teeth and their significance in the clinical management of marginal periodontitis

Anatomic characteristics of the furcation and root surfaces of molar teeth and their significance in the clinical management of marginal periodontitis

Anatomic characteristics of the furcation and root surfaces of molar teeth and their significance in the clinical management of marginal periodontitis.

Treatment of periodontitis which involves the furcation area of molar teeth has always been a challenge. Sixty extracted human molar teeth were used for an anatomic study to clarify the possible morphologic factors which may affect the diagnosis, prognosis, and clinical management of periodontally involved teeth. Teeth were embedded in methylmethacrylate and cut in 70 microm cross sections from the cementoenamel junction to the apex. Cervical enamel projection, root and root trunk lengths, root proximities as well as depths of root concavities coronally, apically, and at the furcation roof were measured. Cervical enamel projections were observed in 30% of the teeth examined. The shortest root trunk was found at the buccal aspect of mandibular first molars, permitting furcation involvement at early stages of periodontal disease. The most apically located furcation was found at the distal site of maxillary first molars. Furcation roofs showed severe concavities and complex cementum morphology. Teeth exhibiting cervical enamel projection were found to have deeper root concavities compared to teeth without cervical enamel projection and mesial roots of mandibular molars possessed greater furcal concavities than distal roots. The presence of root concavities complicates the diagnosis of furcation involvement and restricts access of periodontal instruments, resulting in incomplete treatment. Furcation anatomy may also influence the long-term prognosis of the teeth by favoring the retention of bacterial deposits and making oral hygiene procedures almost impossible. The present study shows that knowledge of a tooth's unique anatomic characteristics is a prerequisite for effective periodontal therapy.

Keratinocyte growth factor mRNA expression in periodontal ligament fibroblasts.

Keratinocyte growth factor (KGF) is a fibroblast growth factor which mediates epithelial growth and differentiation. KGF is expressed in subepithelial fibroblasts, but generally not in fibroblasts of deep connective tissue, such as fascia and ligaments. Here we demonstrate that KGF mRNA is expressed in periodontal ligament fibroblasts, and that the expression is increased upon serum stimulation. Fibroblasts from human periodontal ligament, from buccal mucosa, from gingiva, and from skin were established from explants. Alkaline phosphatase activity was used as an indicator of the periodontal nature of fibroblasts. Cells were first cultured in DMEM with 0.5% fetal calf serum (FCS) and then incubated for 8 h, and 72 h in fresh DMEM with 10% FCS. Total RNA was isolated and used for Northern blotting with a P32-labeled KGF cDNA probe. Total RNA from cultured keratinocytes was used as negative controls. KGF mRNA was found in all cultured fibroblasts. Upon addition of 10% FCS to the cell cultures, an increase in KGF mRNA levels was noticed especially after 72 h. Furthermore, RT-PCR analysis of material scraped from the tooth root surface indicated the presence of KGF mRNA even in noncultured periodontal ligament cells.

A model for the teaching of clinical techniques in root canal treatment.

A practical model to aid the understanding and practice of endodontic techniques is described. The model uses extracted teeth mounted in light-cured acrylic resin and set in a preformed model tray. Before mounting, the root surfaces of teeth are dipped in wax to simulate the periodontal ligament space. This model allows endodontic techniques to be practised in the operative technique classroom in a way that simulates the clinical situation and enables radiographs of good diagnostic quality to be taken during treatment. Subsequently, teeth can be reset to allow restoration of the root-filled tooth.

Expression of bone associated markers by tooth root lining cells, in situ and in vitro

Periodontal disease is marked by inflammation and subsequent loss and/or damage to tooth-supporting tissues including bone, cementum, and periodontal ligament. A key tissue in the initial process of periodontal development as well as regeneration following periodontal disease is cementum. 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., cementoblats). Much has been learned regarding the processes and mechanisms involved in bone formation and function from experiments using bone cell cultures. Therefore, the purpose of this study was to develop a strategy whereby cementoblasts could be isolated, cultured, and characterized. As a first step, using in situ hybridization, we determined the timed and spatial expression of mineral-associated proteins during first molar root development in CD-1 mice. These proteins included dentin sialoprotein (DSP), osteopontin (OPN), bone sialoprotein (BSP), osteocalcin (OCN), and type I collagen. During root development in mice BSP, OPN, and OCN mRNAs were expressed selectively by cells lining the tooth root surface—cementoblasts—with high levels of expression at day 41. Importantly, at this time point BSP, OPN, and OCN mRNAs were not expressed throughout the periodontal ligament. These findings provided us with markers selective to rootlining cells, or cementoblasts, in situ, and established the time (day 41) for isolating cells for in vitro studies. To isolate cells from tissues adherent to the root surface, enzymatic digestion was used, similar to what are now considered classical techniques for isolation of osteoblasts. To determine whether cells in vitro contained root-lining cells and cementoblasts, cultured cells were analyzed for expression of mineral-associated proteins. Cells within this heterogeneous primary population expressed type I collagen, BSP, OPN, and OCN as determined by in situ hybridization. In contrast, cells within this population did not express dentin sialoprotein, an odontoblast-specific protein. These procedures have provided a means to obtain root-lining cells in vitro that can now be cloned and used for studies directed at determining the properties of root-lining cells, or cementoblasts, in vitro.

Underlying mechanisms at the bone-surface interface during regeneration.

The goal of regenerative therapy around teeth and implants is to create a suitable environment in which the natural biological potential for functional regeneration of periodontal ligament and/or bone can be maximized. In order for the regenerative process to be successful, the following factors must be addressed: prevention of acute inflammation from bacteria, mechanical stability of the wound, creation and maintenance of blood clot-filled space, isolation of the regenerative space from undesirable competing tissue types, and the creation of a desirable surface chemistry, energy, roughness and microtopography that can directly influence cellular response, ultimately affecting the rate and quality of new tissue formation and, therefore, the regeneration process. This paper will review how surface characteristics (chemistry and roughness) can affect cell response and local factor production. To evaluate the effect of surface chemistry on cell proliferation and differentiation costochondral chondrocytes were grown on standard tissue culture plastic dishes sputter-coated with different materials. The results indicate that surface materials can elicit differential responses in cell metabolism and phenotypic expression in vitro. In a second study, the effect of varying titanium surface roughnesses on osteoblast-like cell behavior was examined. Surface roughness was found to alter osteoblast proliferation, differentiation and matrix production in vitro. In addition, production of PGE2 and TGF beta by these cells was also shown to increase with increasing surface roughness, indicating that substrate surface roughness also affects cytokine and growth factor production. The role of surface roughness in determining cellular response was further explored by comparing the response of osteoblasts grown on new and previously used surfaces. The results of these latter studies showed that cell proliferation, expression of differentiation markers and overall matrix production are not altered when cells are grown on used vs. virgin surfaces. This suggests the possibility that implants may be re-used, especially in the same patient, if they are appropriately treated. In this context, it should also be noted that rougher titanium surfaces may require more extensive cleaning procedures. From a global perspective, these studies provide some insight into how bone regeneration can be optimized in the presence of an implant or tooth root residing at the site of a bony defect. Since the new bone being produced, during regeneration, grows from a distal area toward the implant or tooth root surface, it is hypothesized that the osteoblasts growing on the surface of the implant may produce local factors that can affect the bone healing process distally. In short, it appears that the surface characteristics of an implant, particularly roughness, may direct tissue healing and, therefore, subsequent implant success in sites of regeneration by modulating osteoblast phenotypic expression.

Characterization of Cementum Derived Growth Factor as an Insulin-Like Growth Factor-I Like Molecule

Cementum is the thin calcified outer layer through which tooth-root surfaces are anchored to soft periodontal connective tissues. A variety of growth factors and adhesion molecules are sequestered in the extracellular matrix of cementum, and we have purified and characterized one of the growth factors. This growth factor, the cementum derived growth factor (CGF), was purified from bovine cementum by acetic acid extraction followed by heparin affinity chromatography and HPLC using cation exchange, molecular sieve, and reverse-phase columns. NaDodSO4-polyacrylamide gel electrophoresis of purified CGF preparation revealed the presence of two major protein bands migrating with Mr 18,000–22,000 and 14,000–16,000. The latter was associated with the major part of the mitogenic activity. The activity of CGF was inhibited by antibodies to insulin-like growth factor-I (IGF-I) and IGF-I receptor. Both CGF and IGF-I were mitogenic to human gingival fibroblasts and alveolar bone cells, but the bone cells responded better to CGF than to IGF-I. The IGF-I did not bind to heparin-sepharose, while CGF bound to it and was eluted with 0.6M NaCl from heparin-sepharose columns. Heparin-sepharose 0.2M NaCl fractions of cementum extracts contained IGF-I migrating with Mr 7,500, but its mobility was not affected by N-glycosidase treatment. Western analysis using anti-IGF-I antibodies showed that CGF preparations contained cross-reacting species migrating with Mr 18,000–22,000, 14,000–16,000 and 11,000–12,000, however after treatment with N-glycosidase the Mr 18,000–22,000 component was absent. Internal amino acid sequences of six tryptic peptides of CGF were determined by microsequencing. The sequence of one 15-amino acid long peptide was the same as the receptor binding domain of IGF-I, and another 9-amino acid peptide had 78% homology to a sequence derived from an untranslated region of sheep IGF-I exon 1. Four other peptides had no apparent homology with IGF-I. From these results we conclude that the CGF is an IGF-I like molecule.

Determination of energy density threshold for laser ablation of bacteria. An in vitro study.

The Nd:YAG and CO2 lasers have been shown to be bactericidal at relative low energy densities. However, at energy densities exceeding 120 J/cm2 (CO2) and 200 J/cm2 (Nd:YAG), laser irradiation also causes irreparable root surface damage. The purpose of this study was to determine, in vitro, the energy density threshold at which microbial ablation could be achieved while inflicting the least amount of damage to the root surfaces of human teeth. Pairs of Escherichia coli colonies cultured on broth agar were treated with a CO2 laser using a pulsed waveform at approximate energy densities ranging from 3 to 110 J/cm2. One of each colony-pair was then examined by scanning electron microscopy (SEM) and the other subcultured for viable microbes. Roots of extracted teeth were lightly scaled and treated by CO2 laser, again with pulsed beam using approximate energy densities of 3 to 110 J/cm2: and examined by SEM. Regardless of the level of energy density, residual bacteria could be subcultured from all laser treated microbial colonies. The inability of the laser to completely obliterate microbial colonies was likely due to: depth of energy penetration, difficulty in precisely overlapping beam focal spots, irregular beam profile, and presence of microbes at the periphery of the beam focal spot. The threshold energy density for bacterial obliteration was determined to be 11 J/cm2 and that for root damage was 41 J/cm2. Root damage was evident by charring, crater formation, melt-down and resolidification surface mineral, and increasing surface porosity. The results of this in vitro study indicate that when used at an energy density between 11 and 41 J/cm2 the CO2 laser may destroy microbial colonies without inflicting undue damage to the tooth root surface.

Therapeutic delivery of calcitonin to inhibit external inflammatory root resorption. I. Diffusion kinetics of calcitonin through the dental root.

Insertion of calcitonin into root canals of monkey teeth has been shown to inhibit external inflammatory root resorption and suppress inflammation. Regulation of this therapeutic event depends upon the rate of arrival (diffusion) of the hormone at sites of resorptive activity. In the present study, the diffusion characteristics of calcitonin through the dental root in an extracted human-tooth model are described, and the role of cementum in the diffusion process is also addressed. Root-canals were endodontically prepared to form a reservoir for [125I]-calcitonin, and macerated to remove organic material from dentinal tubules. In teeth with intact cementum, an initial period of delay (4-5 h) prior to the detection of calcitonin at the external tooth-root surface was followed by a rapid release of the calcitonin during the first 10.5 h (rate peaks at 6 h). Slower, sustained releases of calcitonin through intact cementum were measured for the following 9 days. Removal of cementum, to expose "smear-free" dentine, resulted in an earlier efflux of calcitonin (2 h) at external tooth surfaces and increased amounts of calcitonin release over 9 days. Biphasic delivery of calcitonin by such internal diffusion mechanisms suggests that loss of cementum will enhance therapeutic availability, while prolonged delivery to intact external dental-root surfaces following early intra-canal placement may also be useful for the therapeutic prevention of external inflammatory root resorption.

Scanning electron microscopic observations of apical root surfaces of teeth with apical periodontitis.

The aim of this study was to observe apical root surfaces of teeth with chronic periapical lesions. Five premolars and three molars with radiographically demonstrable periapical lesions were extracted and fixed in 2.5% phosphate-buffered glutaraldehyde solution for 9 days. The apical 3-mm portion of 17 roots was removed and prepared for scanning electron microscope. Lacunar resorption zones were frequently observed on the root surfaces. Bacteria and yeast cells were detected in some of the lacunae. Periapical bacterial plaque with a smooth structure was present mostly around the main apical foramen. Cementum-like tissue deposits indicative of repair were seen adjacent to some resorption areas. Clastic cells tightly attached to crater-like depressions with finger-like projections were observed laterally on the specimens. Current research should be focused on new procedures to eliminate extraradicular microrganisms and periapical bacterial plaque in persistent periapical infections.

A NEW CHALLENGE–ROOT CARIES IN MATURE PEOPLE

The future will bring many more root surface carious lesions in mature adults. Although traditional materials and procedures are acceptable for some patients, most are served best by use of cariostatic resin-modified glass ionomer materials, followed by additional fluoride augmentation for optimum tooth root surface caries prevention.

Bone allografts in periodontal therapy.

Bone allografts as used in dentistry have a 20-year history of safety and efficacy. Case reports and controlled clinical trials have shown the potential of both mineralized and decalcified cortical freeze-dried bone allograft to reconstruct the bone defects caused by periodontitis. Histomorphometric analysis of human biopsies following grafts of decalcified freeze-dried bone allograft have shown the ability of decalcified freeze-dried bone allograft to promote regeneration of new bone, cementum, and periodontal ligament on a tooth root surface previously exposed to bacterial plaque. The addition of mineralized freeze-dried bone allograft and decalcified freeze-dried bone allograft to the guided tissue and guided bone regeneration procedures have significantly enhanced results, especially in large osseous lesions.