Root surface--soft tissue interface. Part I: A review

A comparative analysis of root surface biomodification with ethylene diamine tetra acetic acid and tetracycline hydrochloride: An in vitro scanning electron microscopic study

BACKGROUND

The outcome of periodontal regenerative therapy depends upon the of the biocompatibility root surfaces to the regenerating periodontal tissues. This in vitro scanning electron microscopic (SEM) study was designed to evaluate and compare the demineralizing efficacy of ethylene diamine tetra acetic acid (EDTA), with that of tetracycline hydrochloride applied on to the mechanically treated root surfaces of periodontally involved tooth.

METHODS

Forty specimens were prepared from teeth extracted due to advanced periodontal disease and divided into two groups. The study group was treated with an EDTA solution (pH 7.4) and the control group was treated with a tetracycline hydrochloride solution (pH 1.8). The photomicrographs obtained were assessed for presence of smear layer, number of exposed dentinal tubules, area occupied by tubule orifices along with intertubular surface appearance. The results thus obtained were analyzed statistically.

RESULTS

Both EDTA and tetracycline were effective in removing the smear layer and the exposure of the number of dentinal tubules. The diameters of the tubules and thereby the surface area occupied by the tubule orifices in the EDTA treated group were significantly greater than the tetracycline HCL treated group (p < 0.05).

CONCLUSION

The EDTA produced better effects than tetracycline by providing more demineralized area and collagen exposure at a neutral pH.

EDTA Gel Root Conditioning: Lack of Effect on Clinical and Radiographic Outcomes of Intrabony Defect Treatment With Enamel Matrix Derivative

BACKGROUND

The adjunctive use of enamel matrix derivative (EMD) in the surgical therapy of intrabony defects results in improved outcomes compared to surgical debridement alone. However, the role of EDTA root conditioning in EMD therapy has not been investigated. The purpose of this study was to compare the 12-month outcomes of EMD application with and without EDTA root conditioning in intrabony defect surgical therapy.

METHODS

Twenty-eight chronic periodontitis patients, each contributing a 2- or 3-wall intrabony defect (> or = 4 mm deep and > or = 2 mm wide), participated. Patients consecutively received surgical treatment with either EMD alone (first 13 patients) or EMD + EDTA (subsequent 15 patients). Probing depth (PD), clinical attachment level (CAL), and gingival margin position, i.e., recession (REC) were the clinical parameters recorded. Recorded radiographic parameters were the distances from 1) cemento-enamel junction to bone crest (CEJ to BC), 2) CEJ to base of the defect (CEJ to BD), and 3) BC to BD.

RESULTS

Intragroup analysis showed that both EMD alone and EMD + EDTA led to significant PD reduction, CAL gain, and REC increase 1 year postoperatively. Both groups had >60% mean radiographic defect resolution (change in BC to BD). None of the recorded parameters were significantly different between the two groups, either at baseline or postoperatively.

CONCLUSIONS

These results suggest that clinical and radiographic outcomes of intrabony defect EMD therapy do not depend on the use of EDTA gel root conditioning. The potential contribution of EDTA gel root conditioning to the histological outcomes reported with EMD therapy remains to be determined.

Immunohistochemical study of structural proteins in developing junctional epithelium

The objective of this study was to investigate structural proteins of ameloblasts, reduced enamel epithelium and junctional epithelium using antikeratin antibodies to determine if keratin expression changes as ameloblasts differentiate to cells of junctional epithelium. Block sections of fully erupted, partially erupted and unerupted molar and incisor teeth were removed at necropsy from monkeys age 2, 5, 6 and 7 years. Tissues were fixed in Carnoy's fixative, decalcified in Kristensen's solution for 4 to 8 weeks, embedded in paraffin and sectioned at 5 mu. Representative sections were stained with hematoxylin and eosin. Remaining sections were stained with antikeratin antibodies AE1, AE3, 34 beta E12, 35 beta H11 and anti-40kD using the avidin-biotin-conjugated immunoperoxidase method. Results were analyzed qualitatively for presence or absence of staining products. Antibody 35 beta H11 reacted with ameloblasts and reduced enamel epithelium during the early maturation phase of tooth development but not with the reduced enamel epithelium of erupting teeth or with junctional epithelium. The anti-40kD antibody stained ameloblasts and reduced enamel epithelium of unerupted teeth and teeth erupting through oral epithelium; however, junctional epithelium of partially erupted and fully erupted teeth were unstained. Antibodies AE1, AE3 and 34 beta E12 stained ameloblasts and all layers of reduced enamel epithelium and junctional epithelium in all stages of development. These results suggest a relationship between expression of structural proteins and changes during development and differentiation of ameloblasts to junctional epithelial cells.

Extravascular clot formation and platelet activation on variously treated root surfaces

The platelet attachment and activation potential of a variety of treated, human root surfaces was studied employing an established in vitro method for determining thrombogenicity. In addition, scanning electron microscopic observations were made of the morphological appearance of blood components in initial clot formation on root surfaces containing periodontal ligament (PDL). For the platelet study, the crowns were removed from freshly extracted teeth with and without periodontal disease (PD) and the roots were sectioned. The following surface conditions were created: (1) PDL present, (2) PD, (3) PD planed, (4) PD planed and demineralized, (5) Condition 4 treated with collagenase. All conditions were incubated with Indium-1 ll-labeled platelets with and without the addition of prostacyclin, an inhibitor of platelet activation. It was observed that the greatest number of attached platelets were found in Condition 1, that platelet activation was significantly enhanced in Condition 4 and this effect was reversed by Condition 5. The scanning electron microscopic observations were made on freshly extracted teeth with an intact PDL in which the roots were sectioned and either reinserted immediately into the extraction site or incubated in platelet-rich plasma. It was seen that platelets were involved early in clotting and activated by this surface. This study suggests the possible use of platelet attachment and activation as an indicator for root surface thrombogenicity and perhaps of the fibrous attachment potential.

Lack of effect of citric acid treatment of root surfaces on the formation of new connective tissue attachment

Previous reports have described an accelerated induction of new attachment and repair of furcations in dogs after treatment of roots surfaces with citric acid, but few controlled clinical studies have examined its usefulness in surgical treatments for periodontitis. This study compared the effects of a comprehensive surgical plaque control procedure with or without citric acid treatment for generalized and localized effects on gingival height, probing pocket depth and attachment level in 72 teeth in 3 patients who were treated surgically for moderate periodontitis and examined every 3 months for 1 year. No statistically significant differences in the effects of the 2 treatments were observed. These observations suggest that there is no clinical advantage of citric acid conditioning of the root surface during surgical treatment of periodontitis.

Fluorine concentration changes in human periodontally diseased tooth roots following several treatment times with citric acid

Citric acid conditioning of exposed cementum has become an important adjunct to the clinical management of periodontal disease, and aggressive root planing is recommended to remove hypermineralized and endotoxin-laden diseased cementum. A nuclear resonance reaction technique was used to examine fluorine concentration changes subsequent to application of citric acid (pH 1.0) to the periodontal disease-exposed cementum surfaces of human tooth roots. The technique does not require the test teeth to be sectioned, thereby permitting longitudinal assessments of changes in fluorine concentration and minimizing measurement errors due to the considerable biological variation found between individuals. Initial fluorine concentrations ranged from 0.9%-2.4%, and maxima occurred within 4-6 microns of the surface, suggesting the presence of a hypermineralized layer. Within 60 sec, the citric acid had effectively removed the hypermineralized layer and the previously observed fluctuations in fluorine concentration leveled out at 0.3%-0.5%. Although the results indicated rapid removal of the hypermineralized layer and establishment of fluorine levels normally found in healthy cementum, the experimental design did not permit appraisal of potential effects upon the organic components of periodontally-exposed cementum.

The effect of an air-powder abrasive system on in vitro root surfaces

An air-powder abrasive system, the Prophy-Jet model C-100, is now available for use by the dental community. However, its use has been restricted to cleaning enamel surfaces of stain and dental plaque. The purpose of this investigation was to ascertain the effects of this air-powder abrasive system on root surfaces of extracted human teeth. Thus, root surfaces of 20 teeth were covered with a template consisting of a metal band with a centrally located 2-mm diameter hole. The banded root surfaces, under controlled conditions, were exposed to the air-powder abrasive for 30 seconds. The resulting defects were measured by using a light microscope equipped with a graduated focus knob. Three teeth were randomly selected for examination by scanning electron microscopy and one was selected for histologic evaluation by light microscopy. Untreated extracted teeth were used as controls. In addition, one untreated tooth root was exposed to the air-powder abrasive without use of the template. In this instance, a brush stroke was used for approximately 1 minute, as might be done in a clinical situation. This tooth root was also examined by scanning electron microscopy. The Prophy-Jet air-powder abrasive system removed an average of 636.6 micrometers of root structure in 30 seconds of exposure time. The resulting surface was smooth, free of connective tissue fibers and debris, and all cementum was removed. Few open dentin tubules were observed since most appeared to have been obliterated. The powder crystals, as viewed by scanning electron microscopy, were sharp-pointed, somewhat elongated and of varying lengths. The Prophy-Jet air-powder abrasive system appears to have considerable potential for treatment of periodontally diseased root surfaces. However, its use should be tempered by the results of this and future research and sound clinical judgment.

Root surface smoothness or roughness in periodontal treatment. A clinical study

Twelve patients with localized advanced periodontitis were selected for this study. The 18 teeth used were divided into experimental and control groups. In both groups the loss of attachment and pocket depth were measured and modified Widman flap surgery was performed. In the experimental group, after root planing, a number of shallow horizontal grooves were made on the root surface to roughen them. Four months after surgery the same measurements were made. The results indicated that in both groups the pocket reduction and the gain of attachment were statistically significant. The differences between the two groups, as far as pocket reduction and gain of attachment are concerned, were not significant.

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.

Topography of root surfaces treated in vitro with citric acid, elastase and hyaluronidase. A scanning electron microscopy study. Part II

Sixteen extracted human teeth were separated into two groups, root planed, and treated with either elastase or hyaluronidase following acid demineralization. The duration of enzyme application varied from 5 to 20 minutes. From scanning electron micrographs the following was concluded: (1) The cemental collagen network is composed of previously described extrinsic and intrinsic fiber systems. (2) Root planing, using tactile sense as the final criteria, does not always result in complete elimination of contaminants. (3) Citric acid (pH = 1), applied for 3 to 4 minutes, is an effective means of exposing cemental collagen. (4) Qualitatively, the enzyme treatment subsequent to acid demineralization seemed to result in more effective exposure of the collagen mantle of cementum. (5) Further definitive research must be done to determine, both the usefulness of enzymatic treatment in vitro and in vivo and the optimum enzyme concentrations and duration of application.