Repair or regeneration following periodontal therapy?

Biological Basis of Periodontal Regeneration

The ultimate goal of periodontal therapy is homeostatic regeneration of lost attachment of alveolar bone and gingival connective tissue to the exposed root surfaces with a fully functional and healthy periodontal ligament that is covered with a healthy epithelium. This goal needs a complete understanding of the biological mechanisms inherent to healing and inflammatory processes.

Evaluation of gingival fiber retention technique on the treatment of patients with chronic periodontitis: A comparative study

The destructive action of the chronic periodontitis on the periodontal tissues has provided a continuous challenge to the dental profession to develop better methods to achieve repair of the recession regions and even regeneration of post periodontal tissues.

AIMS

To assess the effect of periodontal muco-periostal flap surgery with gingival fiber retention technique on minimizing the post surgical recession.

MATERIALS AND METHODS

The sample for the study comprised of 20 patients. The criteria for selection included patients with moderate periodontitis, with minimum recession in the anterior teeth, with adequate width of the attached gingiva, and with no traumatic occlusion. Periodontal muco-periosteal flap surgery with gingival fiber retention technique was done in the experimental site with internal bevel incision, and in control site, muco periosteal flap surgery with crevicular incision was done. Thereafter, observation period was of one week, four weeks, and eight weeks were done for both the sites.

STATISTICAL ANALYSIS USED

The results were subjected to statistical analysis using student's t'-test.

RESULTS

The result of this study suggests that the periodontal flap surgery with gingival fiber retention technique has a beneficial effect on the anterior teeth, as it maintains the esthetics, recontours the gingiva with minimal recession. The area of recession was more on the control site as compared to experimental site at 4 weeks, 8 weeks and 12 weeks.

CONCLUSIONS

Gingival fiber retention technique showed less post-surgical recession and also there was fall in values of plaque index, gingival index, and periodontal index scores, throughout the study.

Effects of enamel matrix protein application on the viability, proliferation, and attachment of human periodontal ligament fibroblasts to diseased root surfaces in vitro

OBJECTIVES

The purpose of this research was to examine the influence of enamel matrix proteins (EMP) on the viability, proliferation, and attachment of periodontal ligament fibroblasts (PDLF) to diseased root surfaces.

MATERIALS AND METHODS

Primary cell cultures of PDFL were obtained from clinically healthy third molars or premolar teeth. Viability and proliferation rates were carried out over a 10-day period. A total of 80,000 cells were plated in 24-well plates followed by EMEM with 10% FBS (positive control) and EMEM plus EMP at 25, 50, 75, and 100 micro g/ml. Cells were harvested on days 1, 3, 5, 7, and 10 and viability was performed utilizing an MTS assay. PDLF proliferation rates were assessed by a CyQUANT GR dye assay. SEM analysis was used to examine the qualitative effects of cellular attachment to diseased root surfaces following EMP compared to nontreated controls.

RESULTS

The results indicated that viability was negatively affected for higher doses over time while lower doses displayed viability effects similar to control. Proliferation, however, appeared to be ameliorated following exposure to EMP. The SEM analysis suggests that cellular attachment to diseased dentin was enhanced following EMP application.

CONCLUSION

These in vitro studies support the concept that EMP may act as a suitable matrix for PDLF.

Markers of bone and cementum formation accumulate in tissues regenerated in periodontal defects treated with expanded polytetrafluoroethylene membranes

Guided tissue regeneration (GTR) is a concept that evolved from the development of membrane-barrier techniques, which allow the repopulation of periodontal wounds by specific cells, resulting in a new attachment apparatus. To help understand the biological mechanisms involved in membrane barrier-led periodontal healing, the present study investigated the macromolecules phenotypic of bone and cementum formation in tissues grown under the GTR barrier by immunolocalization. Periodontal regeneration was initiated by placing barriers on experimentally induced periodontal defects in a Rhesus monkey model. Samples were harvested 6 wk after healing and sections of soft tissues grown under GTR barriers (membrane tissue) were stained with antibodies to bone morphogenetic proteins-2 and 4 (BMP-2, BMP-4), bone morphogenetic protein-7 (OP-1), cementum attachment protein (CAP), osteonectin (OTN) and bone sialoprotein (BSP). Tissues grown in the absence of any barrier device served as a control (control tissue). Membrane periodontal tissues from beneath the ePTFE membrane were comprised of spindle-shaped fibroblast-like cells encased in a dense fibrillar extracellular matrix (ECM). Round-shaped cells aggregated to form nodules. Newly formed hard tissue was conspicuous. A similar, but very disorganized, fiber network was observed in control tissues, but neither nodule formation nor hard tissue was observed. Osteonectin staining was observed in the ECM of membrane tissues and particularly in the area of the connective tissue adjacent to newly formed hard tissue. The dense network of connective tissue fibers was also stained. In control tissues, cells and fiber network had a significantly weaker signal for osteonectin. An intense reaction was observed in membrane tissues stained for BSP, particularly the connective tissue adjacent to the newly formed hard tissue, while the control tissues did not stain for BSP. Cementum attachment protein (CAP) was observed in the connective tissue adjacent to the newly formed hard tissue of the membrane tissues whereas control tissues exhibited no CAP staining. In membrane tissues, BMP-2 and 4 distribution was found to concentrate in nodule areas, in the newly formed hard tissue and in the fiber network, while very faint staining was observed in control sections. The distribution of OP-1 in membrane and control tissues was found to mimic the BMP-2 pattern, but staining was more distributed in hard tissue matrix. When the profile of BMP-2, BMP-4, OP-1, OTN, CAP and BSP staining was analyzed on membrane tissue sections, striking similarities were noted in the connective tissue adjacent to the newly formed hard tissue and in nodular areas. In addition, the localization of BMP-2 and BMP-4 mRNA was investigated in both tissues by in situ hybridization. An intense expression of BMP-2 and 4 transcripts was observed in membrane tissues while control tissues never yielded any positive hybridization signal. The correlation between these histochemical findings strongly suggests that the forming soft tissues under ePTFE membranes contain cells and ECM macromolecules normally associated with bone and cementum.

Human periodontal ligament and gingival fibroblast response to TGF-beta 1 stimulation

The purpose of this study was to measure the time-sequence response of RNA and protein synthesis to transforming growth factor-beta 1 (TGF-beta 1) by human periodontal ligament (HPDLF) and gingival (HGF) fibroblasts in culture. HPDLF and HGF were cultured from explants of healthy gingival tissue and freshly extracted teeth. Cultures of 8 x 10(4) cells/ml were exposed to medium containing 3H-uridine and 35S-methionine with TGF-beta 1 at concentrations from 10(-9) M to 10(-21) M, or control medium, for up to 60 hours in order to assess RNA and protein synthesis. Protein concentrations of comparable cultures were also assayed colorimetrically. Results were reported as specific activity (CPM/microgram protein). The results indicate that 10(-9) M TGF-beta 1 treated cultures showed a significant increase in RNA synthesis by HPDLF and HGF over time, as compared to the control cultures. HPDLF showed a significant increase in protein synthesis over time while that by HGF was not significant as compared to the control cultures. Lower concentrations of TGF-beta 1 demonstrated no significant differences from control. Results suggest that the effects of TGF-beta 1 on HPDLF and HGF are both time and dose dependent, with 10(-9) M TGF-beta 1 providing the best response of those concentrations tested. These findings support the concept that TGF-beta 1 may play a role in periodontal regeneration due to its ability to promote fibroblast RNA and protein synthesis. The results also demonstrate that although these two cells types appear morphologically similar, they exhibit distinct biological responses to growth factors such as TGF-beta 1.

Effect of Tisseel on healing after periodontal flap surgery

The purpose of this investigation was to evaluate the effect on healing of fast and slow absorbable Tisseel in combination with periodontal flap surgery. Mucoperiosteal flaps were raised on the buccal aspect of maxillary premolars and mandibular premolars and first molars in 4 beagle dogs. The underlying buccal, interproximal and inter-radicular bone was then removed to a level of approximately 5 mm apically to the original bone crest and half way into the interdental spaces and bifurcations. The exposed root surfaces were curetted in order to remove the periodontal ligament tissue, and a notch was made in the root surface at the base of the defects. On the control teeth, the flaps were sutured immediately after creation of the defects, while on the test teeth, a layer of fast (group I) or slow (group II) absorbable Tisseel was applied between the curetted roots and the subsurface of the flaps prior to suturing. Postoperatively, the teeth were brushed 2 x weekly. The dogs were sacrificed after 4 months. Histological analysis revealed that the amounts of new attachment and bone regrowth were similar in the test and control groups, although the results tended to be most favorable for the group of teeth treated with fast absorbable Tisseel (Group I).

Healing of human suprabony lesions treated with guided tissue regeneration and coronally anchored flaps. Case reports

Teflon membranes were interposed between soft tissue flaps and roots in 4 human suprabony lesions affecting the mandibular incisor teeth in 1 volunteer patient. 4 suprabony lesions affecting the mandibular incisor teeth were used as comparisons in a 2nd patient. All roots were debrided using ultrasonic and manual instruments and the most apical positioned calculus/site on the facial surface was notched. Flaps were sutured as coronally as possible using orthodontic brackets as anchors. Tissue blocks were removed 2 to 3 months after procedures and the facial aspects of all teeth were examined histologically. New attachment in the form of new "cementum with functionally oriented fibers" was seen within the calculus notch in 3 out of 4 membrane-treated sites and immediately apical to the notch at 1 site. The 4 comparison sites showed no evidence of new attachment within or adjacent to the notch. Rather, the gingival margins were located apical to the notch. Our observations suggest that guided tissue regeneration techniques improved coronal attachment responses in human suprabony lesions within the sample described.

Human gingival attachment responses to subgingival crown placement. Marginal remodelling

13 teeth in block were extracted from 2 patients. Their facial periodontal condition was essentially within normal clinical limits. Temporary crowns covering the bevel were placed below the base of the crevice 1 to 8 weeks prior to extraction. At time of extraction, all blocks were decalcified, the temporary crown dissolved, and the blocks prepared for histologic examinations using buccolingual cut, step serial sections. Histologic data revealed reformation of a new supracrestal attachment unit within 1 week following crown placement. The reformation of the gingival unit consisted of marginal recession with apical and lateral migration of the junctional epithelium to the level of remaining cementum inserted fibers. With gingival recession and migration of junctional epithelium, resorption of crestal portions of the facial plate occurred. However, periodontal fibers anchored into cementum opposite the resorbed bone were not lysed. Rather, the attached fibrillar ends appeared to interdigitate with fibers from the corium of the facial gingiva at this site, thereby forming a more apically located crestal attachment. This response may be one mechanism of reformation of the gingival attachment unit taking place following mechanical and/or surgical injury to this site and is completed often, within 2 weeks after injury.

Speculations on periodontal attachment loss

A hypothesis is presented depicting patterns of human periodontal attachment loss. The patterns described occur rapidly, are site-specific and take place in response to virulence and duration of local irritants. They appear to mirror current clinical observations regarding the nature and progress of site-specific periodontal lesions.

Initial physical tests of aluminoborate cements in the context of periodontal dressing development

A new glass ionomer cement system (aluminoborate) is under consideration for dental applications, including the possibility of a periodontal dressing material. Following the development of pertinent adhesive and rheological tests, two experimental formulations were selected by a simple screening procedure and subjected to appropriate adhesive tests. One formulation proved satisfactory and was subjected to a rheological test in addition. The possible role of aluminoborates as periodontal dressing materials is discussed.

Healing responses of human intraosseous lesions following the use of debridement, grafting and citric acid root treatment. II. Clinical and histologic observations: one year postsurgery

This report details histologic healing responses at intrabony sites within two patients about 1 year after surgery. Treatment consisted of open flat debridement of the lesions. At specific sites, augmenting procedures such as autogenous grafts, allografts, synthetic grafts and citric acid root treatment were utilized. In addition, notches were made through calculus prior to root planing at specific root surfaces. These notches were placed at varying distances from the base of the lesion. Patients were followed postsurgically with frequent maintenance visits. Block sections were removed at the end of the experimental period. Clinical reduction in pocket depth was noted at all treated sites. This reduction consisted of limited pocket closure, marginal gingival recession and repocketing. Histologically, all specimens showed evidence of repair. The most mature repair appeared at sites treated with debridement and autogenous grafts. "Regeneration" of lost periodontal attachment was demonstrated by evidence of cementogenesis, osteogenesis and the presence of functionally oriented ligaments. However, the coronal regeneration appeared spatially limited. Allografts showed a similar, but less mature healing response. Synthetic graft material acted essentially as a "filler" within the defect. Citric acid root treatment did not demonstrate clear evidence of augmentation of the repair process. Of particular note in these human specimens was further histologic demonstration that "regeneration" potential apparently can only take place in close proximity to histologically viable periodontal ligament cells which may act as "donor sites" for coronal "regeneration" of lost periodontal attachment. This histologic response was observed regardless of treatment modalities used.

Healing responses of human intraosseous lesions following the use of debridement, grafting and citric acid root treatment. I. Clinical and histologic observations six months postsurgery

Three block sections of treated human intraosseous lesions within one individual are presented. These lesions were debrided, filled with autogenous grafts and at two sites the root was treated with citric acid. The treated sites were lightly root planed once a month and the blocks were removed 6 months after surgery. In addition, the root accretions within two lesions were notched with a bur prior to root planing in order to positively identify the position of these root accretions in the histologic sections. Clinically, the lesions closed by marginal shrinkage and limited pocket closure. Histologically, regeneration of new cementum, osteogenesis at bone and graft spicule seams and reformation of functionally oriented ligament fibers were present at sites within lesions where accretions had covered the root. Such a healing phenomenon was observed close to the base of the lesions and seemed to be related to this spatial configuration rather than to the notching of the root itself. No specific increased healing responses could be attributed to citric acid root treatment. Thus, "regeneration" of new attachment is possible within human intraosseous lesions even at root sites previously covered by accretions. However, such responses seem to be limited to areas near the base of the intraosseous lesion.

Root surface resorption, repair, and periodontal attachment following rapid maxillary expansion in man

This study was designed to investigate human repair and reattachment of principal periodontal fibers in areas of resorption on anchor premolar root surfaces following rapid maxillary expansion. Maxillary first premolar teeth were obtained from patients requiring rapid maxillary expansion. Extraction of the teeth was scheduled after periods of retention varying between 14 and 53 weeks. The roots of the teeth were examined via light microscopy and scanning electron microscopy. Extensive root resorption characterized the buccal surfaces of anchor premolars. Repair of the resorptive defects was found to occur exclusively with cellular cementum. Anchor teeth retained for longer periods, up to the maximum of 53 weeks of retention in this study, generally demonstrated more advanced repair. Topographically, Sharpey fiber holes indicative of principal periodontal fiber insertion were found in repair cementum. However, these depressions were neither numerous nor consistent in their presence and location. In human teeth, periodontal attachment to resorbed and repairing surfaces was shown to be present. SEM studies of histologic sections revealed that periodontal fibers and fiber bundles inserted directly into the repair cellular cementum matrix, irrespective of the site of the lesion on the root.

Periodontal healing following open debridement flap procedures. II. Histologic observations

Four tooth-containing blocks were obtained from patients being treated for infraosseous lesions of significant depth as part of their periodontal therapy. Treatment consisted of open flap debridement and professional cleansing at least every 4 weeks. Teeth in block were removed for histologic study 4 to 6 months after surgery. Histologic evaluation of the repair process showed pocket closure by epithelial and connective tissue adhesions in the form of an elongated junction epithelium, beneath which parallel-oriented fibers adhered to the root for a limited distance. Apical to this adhesion, functionally inserted fibers were present. Since no cementogenesis was seen at these latter areas, it must be assumed that the inserted fibers were present before the surgery and were not significantly affected by the procedure. No significant evidence of crestal osteogenesis was noted. However, comparison of the clinical osseous profile recorded at the time of surgical debridement with the flat crest seen in two of our cases histologically, suggests that significant crestal resorption had taken place postsurgically in some of these lesions.

Periodontal healing following open debridement flap procedures. I. Clinical assessment of soft tissue and osseous repair

The healing response of the periodontium was evaluated after periodontal flap and debridement procedures in patients with different levels of postsurgical plaque control. Thirty-one sites in 19 patients were included. Measurements were performed from a fixed reference point presurgically and before reentry surgery. All reentries were performed 24 to 28 weeks after surgery. Surgery consisted of elevating an inverse bevel mucoperiosteal flap, debriding root accretions and osseous defects, penetrating into the marrow, and suturing with interrupted sutures at or near the presurgical level. All patients were recalled at least once every 4 weeks after surgery fof professional maintenance. The number of postsurgical maintenance visits and plaque scores (NPI) before reentry were recorded for each surgical site. Average pocket depth at the 31 sites was 7.4 mm initially and 4.1 mm at the time of reentry. This reduction in pocket depth consisted of gingival recession, which averaged 2.0 mm, and a gain in attachment level, which averaged 1.4 mm. At no site was there a loss in attachment level. Average osseous depth of the 31 defects was 3.7 mm presurgically and 1.7 mm at reentry. In addition, there was an average crestal resorption of 0.8 mm and an average osseous fill of 1.2 mm. A significant positive correlation (P less than 0.001) was found between gain in attachment, osseous fill and number of postsurgical maintenance visits. A significant negative correlation was found between the amount of plaque (NPI) at the study site and both gain in soft tissue attachment and osseous fill. Multiple measurements at various points within several osseous defects revealed that osseous remodeling and fill varied significantly at different locations within the same defect.