An evaluation of a resorbable (semirigid) GTR membrane in human periodontal intraosseous defects: A clinicoradiological re-entry study.

AIM: To evaluate the effectiveness of a resorbable, semi rigid guided tissue regeneration (GTR) membrane in the treatment of periodontal intraosseous defects. SETTINGS AND
DESIGN: Randomized controlled clinicoradiological re-entry study.
MATERIALS AND METHODS: Eight patients with bilateral, identical intraosseous defects were selected. The sides for test and control group were randomly allocated to treat either with bioresorbable semi rigid membrane (test group) or open flap debridement (control group). Radiographic analysis was done by comparing intraoral peri apical radiographs taken at baseline and at six months. Extended cone paralleling device with grid was used to standardize radiographs. Auto CAD software was used for the analysis. STATISTICAL ANALYSIS USED: Paired-t test.
RESULTS: On surgical reentry at six months, the mean reduction in depth of the defect at the test site was 2.63 mm. The mean gain in Relative attachment level was 1.75 mm. The control sites showed a statistically insignificant gain. The mean percentage defect fill assessed on radiographs using auto CAD software was 15.54%.
CONCLUSION: The resorbable, semi-rigid GTR membrane can be effectively used for the treatment of human one-walled angular defects.

RCT Entities:   Population Interventions Outcomes

INTRODUCTION

Guided tissue regeneration (GTR) can be considered as an effective and predictable surgical approach for the treatment of periodontal intrabony defects,[1] which involves placement of either resorbable or nonresorbable barrier membranes to seclude a space around the diseased root surface, and allows cells from periodontal ligament and alveolar bone to repopulate the defects. Several problems, however, have been associated with the use of non-resorbable barrier membranes including the possibility of membrane contamination and/or infection and the need for a second surgical procedure for membrane removal. Several investigations have indicated that the outcome of GTR procedures can be affected by bacterial contamination of the non-resorbable devices.[2-3] Furthermore, the removal of the membrane is associated with increased morbidity for the patient, time consuming, and can interfere with the maturation of the regenerated tissues during an early and delicate stage of healing. In addition, the optimal timing of resorbable membrane removal has not been unequivocally determined as the healing time and maturation time of hard tissues varies from individual to individual.[4]

Research has led to the development of a second generation membranes*, which have certain advantages over first generation membranes such as enhanced biocompatibility, cell occlusiveness, tissue integration, semi-rigidity; thus space making, improved clinical manageability, and most importantly, resorbability, and therefore, eliminating the need for surgical removal of the membrane.[5]

Many studies done on human and experimental animals have demonstrated the formation of new attachment following guided tissue regeneration therapy in intrabony defects, class II furcations and recession defects.[6-8] In the present study, an attempt has been made to regenerate the lost periodontium in infrabony periodontal defects in human mandibular molar areas using a semi-rigid, resorbable membrane.

MATERIALS AND METHODS

The sample of the study included eight patients, seven males and one female, with bilateral and angular defects. Patients were treated in a split mouth design, and were followed-up for a period of six months. Two different approaches for the treatment of deep intrabony defects were compared in this randomized controlled clinical trial. The test group was treated with a semi rigid bio-resorbable barrier membrane*, and the control group was treated with open flap debridement. Randomization was done using toss of coin method.

Subject population

Following scaling, root planing, and oral hygiene instructions, eight patients with good general health, volunteered to participate in this study with the age group of 30-55 years were selected.

Inclusion criteria

Patients of either sex having chronic periodontitis,

Patients who are systemically healthy with no contraindication to periodontal surgery,

Presence of intrabony defects ≥5 mm with radiographic evidence of affected site,

Patients who are co-operative and able to come for regular follow-ups.

Exclusion criteria

Smokers,

Pregnant/lactating women,

Severe systemic disease,

Patients allergic or sensitive to any medication or any ingredient of the test-material,

Patients showing unacceptable oral hygiene compliance during/after phase-I therapy.

In each patient, bilateral intraosseous predominantly one-walled defects located at the interproximal area were identified. Furthermore, the defects did not extend in to the interproximal region and the involved teeth were not carious, mobile, or non-vital. Baseline plaque scores (Silness and Loe 1964) were in the range of 0-1, and the patients were not under any medication for the past six months.

GTR membrane material

Membrane was made using poly lactic acid (PLA), poly glycolic acid (PGA), and lactide/glycolide copolymer (PLGA).

Radiographic analysis

Intra-oral periapical (IOPA) radiographs were standardized by extended cone paralleling devise‡ with plastic grids, and the tube head angulation, the x-ray unit setting for kVP, mA was adjusted. Radiographs were scanned using a transmission scanner and subjected to volumetric analysis using AutoCAD 2000 software. The scanned images were enlarged uniformly to twice the original dimension for the ease of measurement and the area of interest was demarcated digitally so that the difference between pre- and post-operative radiographs could be easily compared and calibrated. Images were demarcated by drawing a line from the apices of teeth adjacent to the defect, line is continued coronally, parallel to the two roots, and then through the bottom of defect. This gives a quadrangle. Pre- and post-operative changes in the area of the quadrangle were calculated, and the difference gives defect fill. A Periodontist, who was unaware of the test and control radiographs, did the analysis. Further, a single examiner analyzed all the radiographs.

Acrylic stent fabrication

A stone cast was prepared after the maxillary and mandibular impressions, and occlusal stents of clear auto polymerizing resin were fabricated by ‘sprinkle-on method” for both test and control sites. Grooves were made at the suspected defect site near the interdental region so as to guide the UNC-15 probe. A reference marking was drawn on each stent at the lower border so as to get accurate and reproducible measurements at the time of surgery and subsequent re-entry at the end of six months.

Surgical procedure

After local anesthesia, crevicular and inter-dental incisions were placed, followed by envelope flap preparation. Then full thickness mucoperiosteal (envelope) flap was elevated. The interdental papillae were preserved at all sites, as it allows for better coverage of the material interproximally. Pocket epithelium was excised to leave a fresh connective tissue bed in contact with the membrane material. The surgical site was debrided and root planing was done. The acrylic occlusal stent was placed and the measurement of the defect was recorded by using UNC-15 probe from the bottom of the defect to the fixed point on the stent [Figure 1]. Before placing the membrane at the defect site, a sterile surgical template was applied [Figure 2] and approximated for extensions onto the buccal and lingual aspects and trimmed accordingly. The membrane was removed from the sterile package and it was compared to the trimmed surgical template, reduced to the required dimensions. The membrane was now carefully tweezed through the interproximal contact area. The buccal and lingual extensions of the membrane were now inserted under the buccal and lingual flaps, so as to rest on sound bone [Figure 3]. After the placement of the membrane, 4-0 vicryl sutures (absorbable) were used to close the flap with interrupted simple loop sutures were placed after the flap was taken as coronally as possible. A periodontal pack† was applied to the site and left for seven days. Post surgical instructions were given and patients were prescribed amoxicillin 500 mg, thrice a day, for five days, and analgesic, ibuprofen 400 mg, twice daily, for three days.

Figure 1

Pre-operative measurement of depth of defect at the test site

Figure 2

Tin foil template on defect site

Figure 3

Membrane in place

Procedure for surgical re-entry

At the end of six months, surgical re-entry was performed under local anesthesia on both the test and control sites, and measurements were recorded with the help of acrylic stents and UNC-15 probe.

RESULTS

The mean relative attachment levels (RAL) of both test and control sites at baseline was 8.12 mm [Tables 1 and 2]. The baseline depth of the defect (DOD) measurements for both test and control sites with the mean depth of defect were ranging from 11.5 mm and 10.5 mm, respectively [Tables 3 and 4].

Table 1

Pre- and post- operative mean relative attachment level within the test group

Table 2

Pre- and post- operative mean relative attachment level within the control group

Table 3

Pre- and post- operative mean depth of defect within the test group

Table 4

Pre- and post- operative mean depth of defect within the control group

At six months, on clinical examination, the tissues at selected sites were clinically healthy and resisted penetration of the probe, which in turn depicted RAL [Figure 4]. The mean RAL at the test sites was 6.37 mm, depicting a gain of 1.75 mm. At the control sites, the mean RAL was 8.12 mm, showing no gains [Table 5]. At the test sites, the mean depth of the defect was 8.87 mm. showing a gain of 2.63 mm. Where as in control sites, the mean DOD was 9.37 mm, showing a gain of 1.13 mm [Table 6]. The auto CAD percentage values of bone gain in both test and control sites and the mean percentage bone gain in test group was +15.54% and in the control group 1.07%, respectively [Table 7].

Figure 4

Post-operative measurement of depth of defect at 6 months (test site)

Table 5

Post-treatment relative attachment level values between the test and control group

Table 6

Post-treatment depth of defect values between the test and control group

Table 7

AutoCAD percentage values of defect fill in test and control groups at the end of 6 months

DISCUSSION

The goal of periodontal therapy is to regenerate the periodontal tissues destroyed by the disease process using a predictable method. However, most of the conventional periodontal therapies have resulted in unsatisfactory repair due to the rapid proliferation of gingival epithelium. After Nyman et al. reported findings on new attachments including bone and connective tissue by using a barrier to exclude epithelium from the defect sites; GTR therapy has been widely used.[9]

The membrane used in the study has special characteristics including interconnective porous structure which promotes good nutrient flow and blood vessel formation, cell occlusiveness, and biodegradability.[5]

A number of GTR membranes have been evaluated in furcations and three-walled defects. Very few studies have been carried out in one-walled defects because the probability of regeneration is limited due to the inherent anatomical characteristics. The particular design characteristics of the membrane used in our study were conducive for one-walled defects. Hence, these defects were chosen and evaluated in our study.

In this present study, the clinical evaluation included two parameters namely, RAL and DOD. Both of these were measured using a UNC-15 periodontal probe and a customized acrylic occlusal stent which served as a fixed reference point. The fabrication of a groove in the stent for placement of the probe in the desired probing locations offer the advantage of providing a fixed reference point apico-coronally and mesio-distally.[10]

Surgical re-entry at six months in both test and control sites was carried out to assess the efficacy of respective treatments. The re-entry which was performed along with a customized acrylic stent allowed the visualization of residual intrabony defects for the assessment of the amount of bone fill [Figure 4]. This enabled accurate measurements of the levels of bone fill, but did not provide information about the level of new attachment, which can only be assessed through histometric analysis.[10]

The distribution of the data obtained from the results showed a wide range of defect fill. Some defects appeared to have a substantial fill, compared to others. This was in accordance with a study conducted by Mellado et al.[11]

The mean gain in RAL at test sites, after six months was 1.75 mm, while the control sites showed a statistically insignificant gain. However, it was found that the gain in RAL in the test group was statistically significant, when compared to the control groups.

The mean reduction in depth of the defect at test sites was 2.63 mm was achieved, which is in correlation with other studies by Christgau et al.[12], Garrett et al.[13] and Stavropoulos et al.[14] This gain in resolution of osseous defects is attributed to characteristics of the resorbable membrane such a tissue integration, cell occlusivity, clinical manageability, space making, and biocompatibility. A marginal gain was achieved at the control sites which could be due to natural regeneration.

Radiographic assessment of the hard tissue was done using the AutoCAD software, where the region of interest was demarcated on the scanned radiograph, and comparison was made with the demarcated images and percentages of defect fill/loss were analyzed [Figures 5–8]. Using the above described radiological parameters, we found mean percentage defect fill in the test group was 15.54%, which is comparatively lesser than 39% of defect fill achieved by Cortellini, Piniprato and Tonetti et al.[715] The lesser defect fill percentage can be attributed to the fact that the above mentioned authors (clinicians) in their study had a longer follow-up study duration of 12 months, whereas this present study was followed and re-entered in a short span of time (six months).

Figure 5

Pre-operative radiograph of test site between 45 and 46

Figure 8

Post-operative radiograph of control site between 35 and 36

Post-operative radiograph of test site between 45 and 46 at 6 months

Pre-operative radiograph of control site between 35 and 36

From the results obtained we conclude that:

The resorbable, semi-rigid GTR membrane can be effectively used in treatment of human periodontal one-walled angular bone defects.

Analysis of defect fill percentage by Auto CAD revealed substantial defect fill in test sites.

The resorbable, semi-rigid GTR membrane is effective than open flap debridement, thus helpful in favoring resolution of deep intrabony defects and in particular one-walled defects, which were previously not very effectively treated as there were no specific treatment modalities for the above mentioned defects.