Periodontal healing after non-surgical therapy with a new ultrasonic device: a randomized controlled clinical trial.

AIM: The aim of this study was to compare the clinical and microbiological healing outcomes following non-surgical periodontal therapy using the new Vector ultrasonic system versus scaling and root planing (S/RP) with Gracey curettes. MATERIAL AND METHODS: The study comprised 20 chronic periodontitis patients. Using a split-mouth design, both treatment modalities were randomly applied to one quadrant of the upper and the lower jaws each. Clinical and microbiological parameters were assessed at baseline, 4 weeks, and 6 months after treatment. Furthermore, post-operative hypersensitivity was assessed. The Wilcoxon signed rank test (alpha=0.05) was used for statistical analysis. RESULTS: Both therapies provided statistically significant clinical and microbiological improvements of periodontal conditions after 4 weeks and 6 months. Hypersensitive teeth were found only 4 weeks after S/RP. Besides a significantly better bleeding on probing reduction in deep S/RP sites, no other clinical and microbiological parameters revealed significant differences between the sites treated with the Vector system or S/RP. CONCLUSION: Both the Vector system and S/RP provided favourable periodontal healing results, although in deep pockets S/RP appeared to achieve a better resolution of inflammation.

Influence of autologous platelet concentrate on healing in intra-bony defects following guided tissue regeneration therapy: a randomized prospective clinical split-mouth study.

OBJECTIVES: To investigate the influence of autologous platelet concentrate (APC) on early wound healing and regeneration outcomes following guided tissue regeneration (GTR) therapy. MATERIAL AND METHODS: In 25 patients, two contralateral deep intra-bony defects were treated with beta-TCP and a bioresorbable GTR membrane. They were randomly assigned to test and control procedure. In test defects, APC was additionally applied. After 3, 6, and 12 months, healing results were assessed by clinical parameters and quantitative digital subtraction radiography. RESULTS: Post-operative membrane exposures occurred in 48% of the test sites and 80% of the control sites. Both groups revealed a significant clinical attachment level (CAL) gain of 5 mm after 12 months. Eighty-eight per cent of test and control sites showed a CAL gain of > or =4 mm. No clinical parameter revealed significant differences between test and control sites. A significant bone density gain was found in both groups after 3, 6, and 12 months. Only after 6 months, the bone density gain was significantly greater in the test defects. CONCLUSION: Within the limits of this study, autologous platelet concentrate did not seem to have a noticeable influence on the clinical and most of the radiographic outcomes following GTR. However, APC might reduce the occurrence of post-operative membrane exposures and accelerate bone density gain.

Growth factors and cytokines in autologous platelet concentrate and their correlation to periodontal regeneration outcomes.

AIM: To determine the concentration of naturally available biologic mediators in autologous platelet concentrates and their correlation with periodontal regeneration outcomes. MATERIAL AND METHODS: In 25 patients with two intra-bony defects each, an autologous platelet concentrate (APC) was prepared by a laboratory thrombocyte apheresis technique pre-operatively. Both defects were treated using a bioresorbable guided tissue regeneration-membrane in combination with tricalciumphosphate (TCP). In the test defect, APC was additionally applied. In the APC, platelets were counted and the levels of growth factors and cytokines were determined by ELISA. Correlations between the platelet counts or the growth factor/cytokine levels and the potential clinical and radiographic regeneration outcomes due to APC were calculated after 3, 6, and 12 months. RESULTS: The APC contained 2.2 x 10(6) platelets/mul, which was 7.9 times more than in the venous blood. Transforming growth factor-beta1 (TGF-beta1), insulin-like growth factor-I (IGF-I), platelet-derived growth factor-AB (PDGF-AB), PDGF-BB, vascular endothelial growth factor (VEGF), and epidermal growth factor (EGF) were found in the APC, whereas interleukin-1beta (IL-1beta), IL-6, tumor necrosis factor alpha (TNFalpha), IL-4, and IL-10 were not detectable. The regression analysis showed a weak correlation between the platelet counts or the growth factor levels and the clinical and radiographic regeneration outcomes (r2

Periodontal healing after non-surgical therapy with a modified sonic scaler: a controlled clinical trial.

AIM: The aim of this study was to compare the clinical and microbiological healing outcomes following non-surgical periodontal therapy using a modified sonic scaler system versus scaling and root planing (S/RP) with hand instruments. MATERIAL AND METHODS: The study comprised 20 chronic periodontitis patients. Using a split-mouth design, both treatment modalities were randomly applied to one quadrant of the upper and lower jaws. Clinical and microbiological parameters were assessed at baseline, 4 weeks, and 6 months after treatment. Furthermore, post-operative hypersensitivity was investigated. The Wilcoxon signed-rank test (alpha = 0.05) was used for statistical analysis. RESULTS: With both therapy methods, periodontal conditions showed statistically significant clinical and microbiological improvements after 4 weeks and 6 months. Hypersensitive teeth were found only 4 weeks after S/RP. Besides a significantly better bleeding on probing reduction in deep S/RP sites and less time required for root instrumentation by the sonic scaler, no other clinical and microbiological parameters revealed significant differences between sites treated with the sonic scaler or S/RP. CONCLUSION: The sonic scaler system and S/RP seem to provide similarly favourable periodontal healing results, although in deep pockets S/RP appeared to achieve a better resolution of inflammation.

Influence of interleukin-1 gene polymorphism on periodontal regeneration in intrabony defects.

The aim of this controlled retrospective study was to evaluate the influence of an IL-1 gene polymorphism on the clinical and radiographic healing outcomes of GTR therapy. The study included 47 adult periodontitis patients with 94 deep intrabony defects treated by GTR using different membrane materials. The following clinical parameters were recorded at baseline and 12 months after surgery: papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), clinical attachment level (CAL), and the vertical relative attachment gain (V-rAG). Bone changes in the defect regions due to GTR therapy were quantitatively evaluated using digital subtraction radiography (DSR). Polymorphisms of the IL-1A gene at position - 889 and of the IL-1B gene at position + 3953 were analyzed by PCR. Statistical analysis was performed using the Mann-Whitney-U and the Wilcoxon-Signed-Rank tests (alpha = 0.05). The study comprised 19 IL-1 genotype positive (IL-1 +) patients and 28 IL-1 genotype negative (IL-1 -) patients. Twelve months after GTR therapy, both patient groups revealed statistically significant PPD reductions and CAL gain [median (25/75% percentiles)]: Delta PPD [IL-1 + : 4.0 (2.5/5.0) mm; IL-1-: 3.8 (3.0/4.9) mm], Delta CAL [IL-1 + : 3.5 (3.0/4.8) mm; IL-1 -: 3.0 (1, 2/4, 5) mm]. V-rAG amounted to 60.0 (47.7/78.6)% in IL-1 + patients and 53.1 (43.4/81.9)% in IL-1 - patients. Both patient groups showed significant bone density gain in 40% (IL-1 +) and 43.6% (IL-1 -) of the initial defect area due to GTR. Neither the clinical nor the radiographic healing parameters revealed any statistically significant differences in the GTR healing outcome between IL-1 + and IL-1 - patients. In conclusion, these 12-month findings indicate that the IL-1 gene polymorphism has no influence on the clinical and radiographic regeneration results following GTR therapy.

Guided tissue regeneration in intrabony defects using an experimental bioresorbable polydioxanon (PDS) membrane. A 24-month split-mouth study.

AIM: The comparison of the clinical, radiographic, and microbiological healing results in deep intrabony defects following GTR therapy with two different bioresorbable membranes in a prospective split-mouth design. MATERIAL AND METHODS: 31 pairs of contralateral intrabony defects were randomly treated with either an experimental Polydioxanon (PDS) membrane or a Polylactic acid (PLA) matrix barrier. After 6, 12 and 24 months, healing results were assessed using clinical examinations (REC, PPD, CAL, vertical relative attachment gain V-rAG), quantitative digital subtraction radiography (amount and area of bone density changes), and microbiological analysis. RESULTS: Postoperative membrane exposures occurred in 14 PDS and 2 PLA treated sites. 6, 12 and 24 months p.o., both membranes provided a significant gain in CAL [median values: 6 months (PDS vs. PLA: 3.0 vs. 3.0 mm); 12 and 24 months (PDS vs. PLA: 4.0 vs. 4.0 mm)], which corresponded to a V-rAG of 57.1% (PDS) vs. 62.5% (PLA) after 24 months. PDS and PLA treated sites revealed significant bone density gain 6, 12 and 24 months after surgery. 38.8% (PDS) vs. 41.8% (PLA) of the initial defect areas showed bone density gain. While the gain in bone density was significantly greater in PDS than in PLA sites, neither CAL gain nor the area of bone density changes revealed significant differences. Microbiological culture revealed similar bacterial loads in PDS and PLA sites during the first 12 months. CONCLUSION: This 24-month study indicates that the PDS and PLA membranes can provide similar favorable regeneration results in deep intrabony periodontal defects, although considerably more postoperative membrane exposures have to be expected in PDS treated sites.

Marginal adaptation of heat-pressed glass-ceramic veneers to dentin in vitro.

The purpose of the present study was to examine the marginal adaptation of ceramic veneers to dentin at the cervical margins and to enamel at the palatoincisal margins using four dual-curing composite resin cements of different viscosity with their corresponding dentin bonding systems. Thirty-six caries-free human maxillary incisors were prepared for facial ceramic veneers with cervical cavity margins located in dentin. Heat-pressed glass-ceramic veneers (IPS Empress) were inserted adhesively using one of the following luting systems: Sono-Cem (SC) with EBS; Variolink Ultra (VU), Variolink High Viscosity (VHV), and Variolink Low Viscosity (VLV) with Syntac. Both the cervical and the palatoincisal margins of the veneers (tooth/composite resin cement interface and ceramic/composite resin cement interface) were evaluated before and after thermocycling and mechanical loading (TCML) by quantitative margin analysis under a scanning electron microscope (SEM) using an image analysis system. Microleakage was assessed by dye penetration after TCML. Before TCML, SC and VU showed statistically significantly fewer marginal gaps than VHV and VLV. After TCML, SC, VU, and VHV revealed significantly fewer marginal gaps than VLV. TCML had a statistically significant influence on marginal gap formation at both the dentin and enamel margins. After TCML, the percentage of marginal gaps was not significantly different at the cervical dentin than at the palatoincisal enamel margins. Cervical dye penetration after TCML showed no statistically significant differences in microleakage among the four luting systems. In conclusion, this in vitro study showed that similarly favorable marginal adaptations of ceramic veneers to dentin and enamel can be achieved using Sono-Cem, Variolink Ultra, or Variolink High Viscosity with their corresponding dentin bonding systems.

Marginal adaptation of heat-pressed glass-ceramic veneers to Class 3 composite restorations in vitro.

The aim of the present in vitro study was to compare the marginal adaptation and integrity of heat-pressed glass-ceramic veneers to adjacent class 3 composite restorations and to enamel using four dual-curing composite resin cements of different viscosity with their corresponding dentin bonding agents. Thirty-six caries-free human maxillary incisors were first restored with mesial and distal class 3 composite restorations and then prepared for facial ceramic veneers. The cavity margins of the veneers were located either in the class 3 composite restorations or in the residual enamel. Heat-pressed glass-ceramic veneers (IPS Empress) were inserted adhesively using one of the following four luting systems in nine teeth: SonoCem (SC) with EBS; Variolink Ultra (VU), Variolink High-Viscosity (VHV), and Variolink Low-Viscosity (VLV) with Syntac. The veneer margins in the region of the composite restoration and in the region apical to the composite restoration (ceramic/composite resin cement interfaces, composite resin cement/composite restoration interface, and composite resin cement/enamel interface) were evaluated before and after thermo-cycling and mechanical loading (TCML) by quantitative margin analysis under a scanning electron microscope (SEM) using an image analysis system. Furthermore, microleakage was assessed in each tooth by dye penetration after TCML. For all luting systems, SEM analysis revealed excellent marginal adaptation of the ceramic veneers to the composite restorations as well as to enamel. The median percentages of marginal gap formation were 1.1% and less before TCML and 5.1% and less after TCML. The error-rates method revealed no statistical influence of the interface or of the viscosity of the luting material. Maximal values of dye penetration showed a significantly higher microleakage at veneers cemented with VU (median: 86.4%) compared to SC (median: 13.3%). In conclusion, the present data demonstrated that existing clinically acceptable class 3 composite restorations have no negative influence on the marginal adaptation of ceramic veneers. This was valid independent of the viscosity of the dual-curing composite resin cement when SC, VHV, or VLV was used.

Characterization of immunocompetent cells in the diseased canine periodontium.

The beagle dog with naturally occurring periodontal disease is one of the most widely used animal models in periodontal research for histological studies on disease pathogenesis and on the effect of potential therapeutic regimens. However, previous studies were restricted to morphological assessment of immunocompetent cells because of the lack of available cell-specific markers. In this study we systematically characterized the specificity and immunoreactivity of a panel of anti-human antibodies for identification (ABC method) of immunocompetent cells in formalin-fixed, EDTA-decalcified, paraffin-embedded inflamed periodontal tissues obtained from six beagle dogs. Canine lymph nodes and a panel of different human tissues served as positive controls. Polyclonal anti-CD3 immunolabeled canine T-lymphocytes specifically. Anti-CD79alpha (clone HM57) reacted with B-lymphocytes and plasma cells, and CD79alpha (clone JCP117) showed no staining in canine tissues. Neutrophils, monocytes, small macrophages, and keratinocytes reacted with an anti-myeloid/histiocyte antibody (clone MAC387). Anti-CD68 (clones PG-M1 and EBM11) immunolabeled large macrophages and plasma cells. Clone EBM11 also stained osteoclasts and cementoclasts. With the exception of JCB117, all antibodies revealed similarly favorable immunolabeling of canine and human immunocompetent cells. Long-term EDTA decalcification appeared to weaken immunostaining of plasma cells with HM57. MAC387 and CD68 can be used to distinguish macrophages in different differentiation stages in canine periodontal tissues. (J Histochem Cytochem 46:1443-1454, 1998)

Accuracy of quantitative digital subtraction radiography for determining changes in calcium mass in mandibular bone: an in vitro study.

The aim of this in vitro study was to determine the accuracy of digital subtraction radiography (DSR) to detect small changes in calcium mass in alveolar bone adjacent to tooth roots. In each of 4 dried porcine mandible segments, one interproximal and one buccal "defect" region was defined adjacent to a premolar root. A series of cortical and cancellous bone slices with a 50 microns--stepwise increasing thickness (0-5000 microns) were attached to the mandible segments covering the respective "defect" region. Standardized radiographs were quantitatively assessed for density changes using DSR. After dissolving each bone slice in hydrochloric acid, its calcium concentration was photometrically determined. For each bone slice, the mean calcium mass covering a single pixel of the subtraction image was calculated. The Wilcoxon signed-rank test and the Mann-Whitney U-test were used for statistical analysis (alpha = 0.05). A strong linear correlation (r2 = 0.86-1.00; p < or = 0.001) was found between the thickness of the bone slices and their calcium mass. Cortical bone showed a 3.5 times higher mean calcium mass/pixel than cancellous bone. Furthermore, a strong linear correlation (r2 = 0.63-1.00; p < or = 0.001) was found between the mean calcium mass per image pixel and the radiographic density changes. Neither the bone type nor the "defect" localization had a significant influence on radiographic density changes caused by changes in calcium mass. A change in mean calcium mass per image pixel of 0.1-0.15 mg was necessary to be detected by DSR. In conclusion, this study revealed a high accuracy of DSR to detect small changes in calcium mass in alveolar cortical and cancellous bone.

GTR therapy of intrabony defects using 2 different bioresorbable membranes: 12-month results.

This prospective split-mouth study was designed to compare the clinical and radiographic healing results in intrabony periodontal defects 12 months after GTR therapy with 2 different bioresorbable barriers. The study comprised 25 healthy patients with one pair of contralaterally located intrabony defects with a probing pocket depth of > or = 6 mm and radiographic evidence of angular bone loss of > or = 4 mm. The 2 defects of each patient were randomized for treatment either with polylactic acid (PLA) membranes or with polyglactin-910 (PG-910) membranes. The patients received systemic doxycycline (100 mg/d) for 11 days postoperatively. One blinded examiner recorded the following clinical parameters using a pressure calibrated probe at baseline and after 12 months: papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), and probing attachment level (PAL). The vertical relative attachment gain (V-rAG) was calculated as a % of the PAL gain related to the maximum possible attachment gain (expressed by the intraoperatively measured depth of the osseous defect). Geometrically standardized intraoral radiographs were quantitatively evaluated for bone changes (density, area) in the defect region using digital subtraction radiography (DSR). Clinical and radiographic data were statistically analyzed using the Wilcoxon-signed-rank test (alpha=0.05). Postoperative membrane exposures occurred in 9 PLA and 13 PG-910 treated sites. After 12 months of healing, both barrier types provided significant PPD reductions and PAL gain [median (25/75 percentile)]: deltaPPD [PLA: 3.0 (2.0/4.0) mm; PG-910: 3.0 (2.0/4.5) mm]; deltaPAL [PLA: 3.0 (2.5/4.0) mm; PG-910: 2.0 (1.0/4.0) mm]. V-rAG amounted to 60% in PLA sites and 54% in PG-910 sites. DSR revealed significant bone density gain after 12 months. 58.3% of the initial defect area in PLA sites and 54.0% of the initial defect area in PG-910 sites showed bone density gain. Neither clinical nor radiographic data revealed any significant difference between the 2 barrier types after 12 months. In conclusion, this 12-month study demonstrated that PLA and PG-910 membranes provided similar favorable regeneration results in deep intrabony periodontal defects.

Quantitative digital subtraction radiography for the determination of small changes in bone thickness: an in vitro study.

OBJECTIVE: The objective of this study was to determine the ability of quantitative digital subtraction radiography to detect small changes in bone thickness adjacent to tooth roots. STUDY DESIGN: A series of cortical or cancellous bone slices with a 50 microm-stepwise increasing thickness were attached to 4 porcine mandible sections covering buccal and interproximal "defect" regions. Standardized radiographs were quantitatively evaluated for radiographic density changes with the use of digital subtraction radiography. Furthermore, all radiographs were conventionally evaluated by 10 clinicians. The Wilcoxon signed-rank test and the Mann-Whitney U test were used for statistical analysis (alpha = 0.05). RESULTS: A high linear correlation was found between the actual thickness of bone slices and radiographic density changes (cortical bone: r2 = 0.89 to 0.99; cancellous bone r2 = 0.61 to 0.86, p < or = 0.001). A certain increase in bone thickness caused a 3 times higher increase in radiographic density for cortical bone than for cancellous bone (p < or = 0.05). The detection limits of digital subtraction radiography were 200 microm for cortical and 500 microm for cancellous bone, whereas the detection limits of conventional radiography were 600 microm and 2850 microm, respectively. CONCLUSIONS: This in vitro study demonstrated a very high correlation between the objective, quantitative assessment of subtle changes in alveolar bone by digital subtraction radiography and the true changes in bone thickness.

Healing response to non-surgical periodontal therapy in patients with diabetes mellitus: clinical, microbiological, and immunologic results.

The aim of the present study was to monitor clinical, microbiological, medical, and immunological effects of non-surgical periodontal therapy in diabetics and healthy controls. 20 IDDM (insulin dependent, n = 7) or NIDDM (non-insulin dependent, n = 13) diabetic patients (median duration 11.5 years, range of HbA1C: 4.4-10.6%) with moderate to advanced periodontal disease and 20 matched healthy control patients, were subjected to supragingival pretreatment and subsequent subgingival therapy. Periodontal examinations (API, PBI, BOP, PPD, PAL), microbiological examinations (culture), medical routine examinations, and immunological examinations (oxidative burst response of PMNs to TNF-alpha and FMLP) were performed at baseline, 2 weeks after supragingival, and 4 months after subgingival therapy. 4 months after completion of non-surgical therapy, the following compared to baseline significant (p < or = 0.05) changes (delta) of clinical parameters (median) were found in diabetic patients versus control patients: deltaAPI (30.4% versus 36.3%), deltaPBI (22.9% versus 24.2%), deltaBOP (39.5% versus 46.9%). The median % per patient of pockets with PPD > or = 4 mm decreased from 41.9% to 28.3% in diabetics, and from 41.6% to 31.8% in controls. Microbiologically, similar reductions of periopathogenic bacteria were found in diabetics and controls. Neither periodontal data nor the oxidative burst response of PMNs showed any significant difference (p > 0.05) between diabetics and control patients. In this study, periodontal therapy had no significant influence on medical data of diabetics. In conclusion, this study indicates that metabolically well-controlled diabetics might respond to non-surgical periodontal therapy as well as healthy control patients.

Periodontal regeneration of intrabony defects with resorbable and non-resorbable membranes: 30-month results.

The aim of this prospective split-mouth-study was to compare the healing results in intrabony defects 12 and 30 months after placement of resorbable (polyglactin-910) and non-resorbable (e-PTFE) GTR-membranes. 11 healthy patients with 30 defects participated. 10 patients with 10 pairs of contralateral lesions, which were treated with both membrane types, were included in the split-mouth-design. Furthermore, in an additional group-design all 30 (16 polyglactin-910 and 14 e-PTFE) treated sites were evaluated. Clinical examinations (PBI, REC, PPD, PAL) and radiographic examinations were carried out under standardized conditions immediately before as well as 12 and 30 months after surgery. Additionally, for the assessment of the effectiveness of the 2 membranes by comparing the regeneration results of different defects, the vertical relative attachment gain (V-rAG) was calculated as a % of the PAL gain related to the maximum possible attachment gain (expressed by the baseline depth of the osseous defect intraoperatively measured). Digital subtraction radiography (DSR) was carried out for the quantitative assessment of bone density changes due to GTR. In the split-mouth-design, both types of membranes provided significant V-rAGs (median) after 12 months (polyglactin: 81.7%; e-PTFE: 100.0%) and after 30 months (polyglactin: 69.1%; e-PTFE: 83.8%) compared to baseline. In 90.0% of the polyglactin and e-PTFE sites, a probing attachment gain of at least 2 mm was maintained over the 30-month period. However, in 2 polyglactin treated sites, and 5 e-PTFE treated sites, a new attachment loss was found between 12 and 30 months. DSR showed bone density gain 12 and 30 months postsurgically. No statistically significant differences could be observed between the 2 membrane materials with regard to clinical and radiographic findings. This was confirmed when considering the total number of defects (group-design). In conclusion, based on this 30-month-study resorbable polyglactin membranes may be regarded as a useful alternative to the well established e-PTFE membranes for the treatment of intrabony defects.

Postoperative exposure of bioresorbable GTR membranes: effect on healing results.

The goal of this investigation was to evaluate the effect of postoperative exposure of two different bioresorbable membranes on the guided tissue regeneration (GTR) healing results compared to nonexposed sites. In each of 25 patients one pair of contralateral intrabony lesions was treated either with polylactic acid (PLA) or polyglactin 910 (PG-910) membranes. Postoperative exposure occurred in 9 PLA and 13 PG-910 sites. Standardized clinical [papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), probing attachment level (PAL)] and radiographic examinations (digital subtraction radiography) were performed immediately before (baseline) and 6 and 12 months postoperatively (p.o.). Subgingival bacterial samples from surgical sites were evaluated by culture at baseline, 6 weeks, and 6 and 12 months p.o. Six months after surgery the changes (delta) of REC were significantly (P < or = 0.05) greater in exposed than in nonexposed sites, independently of the membrane material (median): exposed sites, delta REC = -1 mm; nonexposed sites, delta REC = 0.0 mm. However, 12 months p.o. no significant differences were found due to a decrease in the initial recessions in exposed sites. Although a higher percentage of exposed than nonexposed sites harbored periodontal pathogens 6 weeks p.o. at the gingiva-faced membrane surface, membrane exposure did not have a significant negative effect on delta PPD, delta PAL, or radiographic bone density changes 6 and 12 months p.o. Both membranes showed significant gains in PAL and bone density in both exposed and nonexposed sites. In conclusion, this study demonstrates that with consistent infection control the postoperative exposure of PLA and PG-910 membranes has no significant negative effect on the regeneration outcome, although higher initial gingival recessions must be expected than in the nonexposed sites. However, in exposed sites plaque and infection control were clearly impeded by the rough, exposed membrane surfaces and by the initially negative gingival morphology.

Quantitative digital subtraction radiography for assessment of bone density changes following periodontal guided tissue regeneration.

OBJECTIVES: The quantitative assessment of alveolar bone density changes in periodontal defects following guided tissue regeneration (GTR). METHODS: Twelve patients with 30 intrabony lesions and 16 furcation defects took part. Standardized radiographic and clinical examinations were carried out immediately before and then 5 and 13 months after surgery. Intra-oral radiographs were evaluated by means of digital subtraction radiography (DSR). Within the subtraction images, a window ('experimental region') was defined covering the visible density changes in the defect area. Background noise was measured by using a similarly sized window ('control region') located in an area not affected by GTR. Bone density changes were quantitatively evaluated by calculation of the mean, standard deviation and maximum and minimum values of the grey-level histogram within these windows. RESULTS: DSR revealed significant bone density gain after GTR in intrabony and furcation defects. While a continuous increase was observed over the 13 month period in intrabony defects, changes in furcation defects occurred mostly in the 5-13 month period. Clinically, a distinct vertical and horizontal attachment gain was found. The correlation coefficients between changes in radiographic density and clinical parameters were low, indicating a difference in the information obtained by the two diagnostic methods. CONCLUSION: Quantitative DSR is a valuable, non-invasive, objective method to obtain information on density changes in intrabony and furcation defects treated by GTR. However, a full assessment of soft and hard tissue changes requires both clinical evaluation and DSR.

Clinical and radiographical split-mouth-study on resorbable versus non-resorbable GTR-membranes.

The aim of this prospective split-mouth-study was to compare the 5-months-healing results after implantation of resorbable (Polyglactin-910) and non-resorbable (e-PTFE) GTR-membranes. 12 healthy patients with 41 periodontal defects were treated. Radiographical and clinical examinations (papillary bleeding index, gingival recession, probing pocket depth, probing attachment level, and furcation depth) were carried out under standardized conditions immediately before and 5 months after surgery. The vertical relative attachment gain (V-rAG) was calculated as a % of the bony defect depth (intra-operatively measured) at baseline, and the horizontal relative attachment gain (H-rAG) as a % of the furcation depth at baseline. The standardized radiographs were evaluated blind by 4 experienced examiners for changes of the alveolar bone. Furthermore, digital subtraction radiography was carried out using the standard deviation of the grey level histograms in the experimental region and in a control region as a test parameter for bone changes. Both types of membranes achieved an attachment gain. Using the split-mouth-design, no statistically significant (< or = 0.05) difference between the two membranes could be detected (number of defects/median) with regard to V-rAG (Polyglactin: 12/77.5%, e-PTFE: 12/73.2%) or to H-rAG of class-II-furcations (Polyglactin: 5/66.7%, e-PTFE: 5/66.7%), or to bone changes using conventional and subtraction radiographic evaluation. In conclusion based on this 5-months-study, the resorbable membranes provided attachment gain comparable to the e-PTFE-membranes.