Clinical comparison of resorbable and non-resorbable barriers for guided periodontal tissue regeneration.

The purpose of this study was to compare the clinical results of guided periodontal tissue regeneration (GPTR) using a resorbable barrier manufactured from a copolymer of polylactic and polyglycolic acids (Resolut Regenerative Material) with those of non-resorbable e-PTFE barrier (Gore-Tex Periodontal Material). 12 subjects participated, 6 with similarly paired class II furcations and 6 with 2 similar 2, 3-wall periodontal lesions. The resorbable and non-resorbable barriers were randomly assigned to 1 defect in each subject. Non-resorbable barriers were removed in six weeks. Plaque index (PlI), gingival index (GI), probing depth (PD), clinical attachment level (CAL) and gingival recession (R) were recorded at baseline, (i.e., immediately prior to surgery) and at 12 months postsurgically. The clinical healing was similar and uneventful in both groups. Intrabony pockets depicted significant changes from baseline (p < 0.05) for probing depth reduction and gain in clinical attachment levels. No differences were found between treatments. Class II furcations showed significant improvements from baseline (p < or = 0.05) for probing depth reduction and clinical attachment gain. No differences were detected between treatments. It is concluded that the resorbable barrier tested is as effective as the nonresorbable e-PTFE barrier for the treatment of class II furcations and intrabony defects.

Clinical effects of chlorhexidine mouthwashes on patients undergoing orthodontic treatment.

This study compared the short-term clinical effect of 0.12% chlorhexidine gluconate and placebo mouthrinses in 30 adolescents (ages 11 to 15) undergoing orthodontic treatment. Subjects were randomized into experimental (CHX) and control (C) groups. Baseline values were recorded 10 days after prophylaxis and included Plaque index (PI), Gingival index (GI), Rentention Index (RI), Discoloration index (DI), and probing depths (PD). Both groups (CHX and C) received soft toothbrushes with instructions to brush twice daily, as well as the CHX and placebo mouthrinses, respectively, with oral and written instructions for rinsing twice daily with 15 ml for 30 seconds. Reevaluations were performed 1, 2, and 3 months after baseline, except for the DI and PD, which were only assessed at 3 months. The Student's t test and the paired t test were used to analyze the data at the P < 0.05 level of significance. No differences between groups were seen at baseline for any of the parameters. At 30 days, there was a significant difference for the RI between CHX (0.15 +/- 0.16; mean +/- SD) and C (0.05 +/- 0.06) at the mesial buccal, and for CHX (0.07 +/- 0.10) and C (0.02 +/- 0.05) at the midbuccal. The 60-day evaluation showed similar results. At 90 days, lower PI were observed in the CHX group at the distal buccal (0.38 +/- 0.19), midbuccal (0.22 +/- 0.17), and mesial buccal (0.47 +/- 0.22) sites as compared with the C group (0.97 +/- 0.38, 0.83 +/- 0.40, and 0.95 +/- 0.43, respectively). A similar trend was noted with the GI, as the lower values were related to the CHX group. The changes of the PI and GI, at 30, 60, and 90 days, as analyzed by the paired t test, were statistically significant in the case of the experimental group, as the changes in the means were a reflection of significantly lower scores observed in the experimental group. After 3 months, the DI showed higher scores in the experimental group as compared with the control, but they were not statistically significant. Deeper PD were detected in the C group at 90 days, and they were statistically significant, except for the midlingual site. The RI did not show significant differences at 90 days, but higher values were recorded in the CHX group. The data indicate that the use of the CHX, in addition to regular oral hygiene habits, was effective in reducing plaque and gingivitis in adolescents undergoing orthodontic treatment.

Guided periodontal tissue regeneration in interproximal intrabony defects following treatment with a synthetic bioabsorbable barrier.

This study evaluated guided periodontal tissue regeneration (GPTR) wound healing in interproximal intrabony periodontal defects following surgical treatment with a synthetic bioabsorbable barrier made from a copolymer of glycolide and lactide. Periodontal lesions were induced around the mandibular central incisor teeth of 10 adult male rhesus monkeys using orthodontic elastics. Once similar contralateral interproximal defects had been created, the elastics were removed and an oral hygiene program was initiated and maintained until completion of the study. Three weeks after commencing oral hygiene, flap surgery was performed in the mandibular incisor region and the root surfaces were thoroughly scaled and root planed to the apical portion of the defects. On the test sites, a bioabsorbable barrier was placed over the entire interproximal periodontal defect. Control sites did not receive a barrier. Five months after surgery, the animals were sacrificed and the teeth with their supporting periodontium were processed for light microscopic evaluation. Postoperative clinical healing progressed uneventfully and was similar in both control and test sites. Histologic observations from control specimens indicated reparative healing characterized by a long junctional epithelium with limited cementum and bone formation. Test specimens exhibited significantly more new connective tissue attachment, cementum deposition, and bone formation than the control sites (P < 0.001). The barriers had been completely resorbed with no apparent adverse effect on periodontal wound healing. It was concluded that this bioabsorbable barrier facilitated GPTR wound healing in interproximal intrabony periodontal defects.

Guided periodontal tissue regeneration in Class II furcation defects following treatment with a synthetic bioabsorbable barrier.

The purpose of this study was to evaluate guided periodontal tissue regeneration (GPTR) wound healing in Class II furcation defects following surgical treatment with a synthetic bioabsorbable barrier manufactured from a copolymer of glycolide and lactide. Periodonal lesions were induced in four adult male rhesus monkeys around the mandibular first, second, and third molar teeth using orthodontic elastics. After obtaining approximately 30% bone loss, the elastics were replaced by a stainless steel wire which had a projection extending into the furcation. Once similar contralateral Class II furcation defects had been created, the wires were removed, and an oral hygiene program was initiated and maintained until completion of the study. Three weeks after commencing oral hygiene, flap surgery was performed in the mandibular molar region and the root surfaces were thoroughly scaled and root planed to the apical portion of the defects. A bioabsorbable barrier was then placed to cover the furcation defects on one side of the jaw (i.e., test sites). No barriers were placed on the contralateral molars (i.e., control sites). Five months after surgery, the animals were sacrificed and the teeth with their supporting periodontium were processed for light microscopic evaluation. Clinical healing progressed normally and was similar in both groups. Histologic observations from control specimens indicated repair with epithelium and connective tissue occupying the majority of the furcation defects. Test specimens exhibited definitive evidence of regeneration with significantly greater new connective tissue attachment, cementum deposition, and bone formation than the control sites (P < 0.001). It was concluded that this bioabsorbable barrier facilitated GPTR wound healing in Class II furcation defects.

Healing of intrabony defects and its relationship to root canal therapy. A histologic and histometric study in dogs.

The purpose of this study was to evaluate the importance of root canal therapy in the healing process of severe intrabony defects. Four beagle dogs were used and 32 interproximal intrabony defects, up to the apical third, were created. Wire ligatures were placed into these defects for plaque accumulation. Three weeks later, the ligatures were removed and 4 different treatment modalities were employed: group 1) scaling and root planing (SRP); group 2) modified Widman flap (MWF); group 3) modified Widman flap and root canal therapy performed at the same time (RCT/MWF); and group 4) modified Widman flap and root canal therapy performed 3 weeks after the surgical procedure (MWF + RCT). Postoperative oral hygiene was obtained by spraying a 0.12% chlorhexidine solution 3 times a week. The animals were sacrificed 7 weeks after treatment. Blocks were obtained and processed for routine histology. Results were expressed as a percentage of the total defect length (TDL). No differences were observed when SRP was compared to MWF. New bone formation (BF) presented better results for SRP (43.4%) and MWF (53.4%) when compared to RCT/MWF (15.5%). New cementum formation (CF) presented better results for SRP (59.8%) and MWF (64.6%) when compared to RCT/MWF (19.3%) and MWF + RCT (31.5%). Connective tissue repair (CTR) presented better results for SRP (72.4%) and MWF (74.2%) when compared to RCT/MWF (47.5%) and MWF + RCT (44.4%). Results were statistically significant at the level of 0.05. Within the limits of this study, it was concluded that root canal therapy performed simultaneously or 3 weeks after surgery modified the healing of intrabony defects, impairing new bone formation, new cementum formation and new attachment.

Treatment of peri-implantitis using guided bone regeneration and bone grafts, alone or in combination, in beagle dogs. Part 2: Histologic findings.

The aim of this study was to histologically evaluate and compare the treatment of ligature-induced peri-implantitis using guided bone regeneration, two bone grafts alone, or guided bone regeneration combined with one of the two bone graft materials. Mandibular premolars and first molars in seven beagle dogs were extracted. After placement of Brånemark implants and connection of abutments, experimental peri-implantitis was induced. Flap surgery was performed, abutments were removed, and implant surfaces were treated with an air-powder abrasive unit. Bony defects were randomly treated with either (1) debridement only; (2) debridement plus resorbable hydroxyapatite; (3) debridement plus canine demineralized freeze-dried bone; (4) debridement plus guided bone regeneration; (5) debridement plus resorbable hydroxyapatite and guided bone regeneration; or (6) debridement plus canine demineralized freeze-dried bone and guided bone regeneration. Four months after surgery, a flap was elevated and the barriers were removed. One month later, the animals were sacrificed, and the implants with their supporting peri-implant tissues were processed for histologic evaluation. Guided bone regeneration procedures resulted in the greatest amount of new bone formation, followed by bone grafts alone, and flap debridement. There was no significant difference between guided bone regeneration and both guided bone regeneration/graft combinations in terms of bone regeneration; however, the guided bone regeneration/graft combinations resulted in a greater amount of "reosseointegration" than all of the other treatments. Therefore, the combination of guided bone regeneration with either demineralized freeze-dried bone or resorbable hydroxyapatite appears to be the treatment of choice for plaque-induced peri-implant defects.

Effectiveness of an irrigating solution utilized during ultrasonic scaling.

The objective of this study was to determine whether removal of calculus was enhanced when ProSol PDS 22-4, an irrigating solution, was utilized during ultrasonic cleaning rather than a control (water). Thirty individuals with incipient-to-moderate generalized periodontitis who had not received previous root instrumentation were randomly divided into two equal groups. Baseline examinations included Plaque Index, Gingival Index, Retention Index, pocket depths, clinical attachment levels, bleeding on probing, and Discoloration Index. Immediately after treatment by ultrasonic scaling and the irrigation with either ProSol or water, and 2 weeks postscaling, the clinical parameters were reevaluated. Baseline mean Retention Index revealed no differences between experimental and control groups for any of the surfaces; however, immediately after instrumentation, significant differences were found between treatments in favor of the experimental condition.

Treatment of peri-implantitis using guided bone regeneration and bone grafts, alone or in combination, in beagle dogs. Part 1: Clinical findings and histologic observations.

The purpose of this study was to evaluate and compare the treatment of ligature-induced peri-implantitis using guided bone regeneration and two bone grafts alone and in combination. Mandibular premolars and first molars were extracted from four beagle dogs and after 3 months of healing, three Brånemark implants were placed on each side of the mandibles. Following abutment connection 3 months later, experimental peri-implantitis was induced by tying plaque-retentive ligatures around all abutments. Ligatures and abutments were removed after 3 months, and bony defects measured and treated with either: (1) debridement only; (2) debridement plus resorbable hydroxyapatite; (3) debridement plus canine freeze-dried demineralized bone; (4) debridement plus guided bone regeneration; (5) debridement plus resorbable hydroxyapatite and guided bone regeneration; or (6) debridement plus canine freeze-dried demineralized bone and guided bone regeneration. Pretreatment and 4-month-posttreatment comparison revealed a significant but variable degree of clinically appreciable hard tissue fill with all treatment procedures. Guided bone regeneration procedures resulted in the greatest fill, followed by bone grafts alone and flap debridement. There was no significant difference between guided bone regeneration and both guided bone regeneration/graft combinations; therefore, guided bone regeneration procedures appear to be a predictable treatment for plaque-induced peri-implant defects.

Vascular changes following mucoperiosteal flap surgery: a fluorescein angiography study in dogs.

This study was undertaken to determine the vascular changes which occur following mucoperiosteal flap surgery where two different suturing techniques were employed. In four healthy adult mongrel dogs, buccal and lingual full-thickness envelope flaps were reflected in the mandibular quadrants following intravicular incisions from the first premolar to the first molar. The flaps were immediately readapted and primary closure was achieved by the horizontal mattress suturing technique in one quadrant and the direct interrupted suturing technique in the contralateral quadrant of each dog. A simple photographic system was developed for recording the in vivo gingival circulation depicted by fluorescein angiography just prior to surgery and then after surgery on days 1, 3, 7, 10, 14, and 21. The flaps were divided into three interproximal and two mid-buccal sites for analysis and the intracapillary and diffusion extent of dye fluorescence was accurately quantified by computerized planimetry. As healing progressed, longitudinal changes relative to presurgical baseline were analyzed by paired t-test. Cross-sectional comparisons utilizing Student t-test allowed for evaluating differences between the two suturing techniques as well as differences between interproximal versus mid-buccal sites at each postsurgical day. It was found that the simple act of raising a mucoperiosteal envelope flap initiates significant vascular trauma. Statistically significant reductions in flap circulation relative to presurgical baseline lasted for at least 3 days but persisted for 7 days at the interproximal sites. Flap diffusion (extravascular leakage) recovered sooner and extended over a significantly greater area of the flap than did intracapillary flap circulation during the early period of healing.(ABSTRACT TRUNCATED AT 250 WORDS)

The surgery of extracranial vascular occlusive disease.

The task of reducing the entire field of extracranial cerebrovascular disease to a review of this brevity may be Sisyphean. The surgical therapy of extracranial cerebrovascular disease has developed into an established mode with excellent support from major clinical trials. In regards to symptomatic carotid disease, the North American Symptomatic Carotid Endarterectomy Trial (NASCET), and the European Carotid Surgery Trial (ECST) have both strongly endorsed surgical therapy in patients with 70 to 99 percent stenosis. In the near future, results from two major asymptomatic trials, Asymptomatic Carotid Artery Stenosis Study (ACAS) and Asymptomatic Carotid Stenosis Veterans Administration Study (VA No. 167) should be available to illuminate the controversies of asymptomatic disease. Undoubtedly, new technologies such as duplex scanning and magnetic resonance angiography will have greater roles in the screening of our rapidly aging population for these diseases. Finally, vascular surgery, a major consumer of high technology in hospital resources, will be continually scrutinized by the regulating agencies in the future. It will behoove all interested parties to pursue in hospital registries for monitoring of outcome data in this evolving field.

Guided tissue regeneration: comparison of bioabsorbable and non-bioabsorbable membranes. Histologic and histometric study in dogs.

This study examined histologic and histometric responses to 2 bioabsorbable membranes made from a synthetic copolymer of glycolide and lactide. They were tested for their biocompatibility, resorption characteristics, and ability to support periodontal regeneration. Expanded polytetrafluoroethylene (ePTFE) was used as control. Nine fox hound dogs with no periodontal disease were used. They were sedated and their teeth thoroughly scaled and root planed. Plaque control was maintained. Two weeks later, each dog was anesthetized using gas anesthesia. Buccal and lingual mucoperiosteal flaps were reflected in the mandibular premolar areas. Randomly selected, buccal alveolar bone was reduced on the 2nd and 4th premolars to a level 5 to 8 mm apical to the cemento-enamel junction creating a Class II buccal furcation defect on one quadrant, while the other quadrant received a Class II buccal defect only on the 4th premolar. Root surfaces were denuded of periodontal ligament and cementum, and notches were placed at the bone level of each root. In one quadrant, one site received Type I membrane and the other site received Type II. The contralateral quadrant received ePTFE. Flaps were positioned slightly coronally and sutured. Sutures were removed 1 week later. One month after surgery, 3 dogs were sacrificed and ePTFE barriers were removed from the remaining 6 dogs. Of these, 3 were sacrificed 3 months after surgery and the other 3 at 6 months. Undemineralized experimental tissues were embedded in methylmethacrylate and 8 to 10 microns thick sections were cut in a bucco-lingual direction throughout the mesiodistal extension of the tooth.(ABSTRACT TRUNCATED AT 250 WORDS)

Guided tissue regeneration with dentin biomodification.

This study was undertaken to provide histologic observations on the effectiveness of citric acid and tetracycline HCl root surface demineralization when used in conjunction with guided tissue regeneration (GTR) procedures. Eight beagle dogs with naturally-occurring periodontitis were initially treated with scaling and root planing. Four weeks later, 12 mandibular quadrants were treated surgically with modified Widman flap and expanded polytetrafluoroethylene (ePTFE). The teeth in 4 of the quadrants were randomly root conditioned with tetracycline HCl, while those in 4 additional quadrants were randomly treated with citric acid. ePTFE membranes were sutured in place. The beagles received prophylaxis (chlorhexidine and toothbrushing) 3 times a week. After 6 weeks, the membranes were removed; prophylaxes continued for 4 months. Histological evaluation revealed new cementum on the root surfaces. A new periodontal ligament with fibers inserting into the new cementum was noted. Statistical evaluation of the buccolingual measurements demonstrated membranes alone resulted in significantly more new connective tissue and new bone formation than membranes with root conditioning agents. Within the furcation, no significant differences were found. However, there was a trend for more bone formation with membranes alone. Within the limits of this study it may be concluded that GTR utilizing an ePTFE membrane results in new connective tissue attachment and bone regeneration in the beagle dog. Root surface demineralization with citric acid or tetracycline HCl does not enhance the results achieved with GTR when used alone.

Guided tissue regeneration and bone grafts in the treatment of furcation defects.

The present study evaluated the effects of guided tissue regeneration (GTR), with and without demineralized freeze-dried cortical bone grafts, in the treatment of furcation defects in 4 female beagle dogs with naturally occurring periodontal disease. The root surfaces were thoroughly debrided. Four weeks later, full thickness facial and lingual mucoperiosteal flaps were reflected using inverse bevel incisions on both sides of the mandible involving the 2nd, 3rd, and 4th premolar, and the 1st molar teeth. Following debridement, notches were placed on the roots at the level of supporting bone. Test quadrants were randomly selected and furcations were filled with reconstituted, demineralized, freeze-dried human cortical bone grafts. Following bone grafting, all defects were covered with an expanded polytetrafluoroethylene (ePTFE) membrane, which was sutured with 4-0 sutures. Afterward, interproximal sutures were placed through the flaps, assuring the flaps covered the membranes completely. The contralateral side, serving as control, was treated by debridement only and application of ePTFE membrane. All membranes were removed 6 weeks after surgery. Dogs were sacrificed at 4 months after surgery. Both mesio-distal and bucco-lingual histologic sections were evaluated by descriptive histology. Linear measurements and surface area determination of the furcal tissues were carried out using the microscope attached to a digitizer. Twelve to 20 nonserial sections were made of the mid-buccal aspects of each root of each treated tooth. Half of these sections were stained with Harris' hematoxylin and eosin (H&E) and the other half stained with Mallory's trichrome stain.(ABSTRACT TRUNCATED AT 250 WORDS)

Histologic and histometric responses to polymeric composite grafts.

The present study was designed to determine whether a polymeric composite promotes new attachment in artificially-induced bony defects in the dog model. HTR, hard tissue replacement, is a non-resorbable calcium-layered polymer of polymethyl-methacrylate and hydroxyethyl-methacrylate. It has been reported to be clinically non-inflammatory, osteophilic, and osteoconductive. For the study, 4 beagle dogs, 4 to 6 years old with no periodontal disease were used. Mucoperiosteal flaps were raised including the 2nd, 3rd, and 4th maxillary premolars. Buccal Class II furcation defects were created on these premolars. Reference notches were placed in the roots at the level of the bony defects. Test quadrants were selected by the toss of a coin, and furcations were filled with the polymeric composite particles wetted with sterile saline. Following grafting, the flaps were approximated and sutured. The contralateral side, serving as control, was treated by flap debridement only. Sutures were removed 7 days after surgery. Dogs were sacrificed 4 months following surgery. Mesio-distal histological sections were evaluated by descriptive histology. In addition, surface area determinations (in mm2) of the furcal tissues were carried out using the microscope attached to a digitizer and a computer. In 8 mesio-distal serial sections cut 30 microns apart in both experimental and control teeth, surface area determinations relative to the furcations were made evaluating: 1) the total fill of the furcation; 2) the area filled with alveolar bone; 3) the area occupied by connective tissue; 4) the area occupied by new deposited cementum; and 5) the area filled by epithelium.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro effects of citric acid application techniques on dentin surfaces.

The present study evaluated the in vitro effects of different application techniques of citric acid on dentin root surfaces. Ten freshly extracted, periodontally involved teeth were obtained and 4 dentin slabs, approximately 4 x 6 x 2 mm, were obtained from the roots of each tooth, for a total of 40 slabs. These slabs were identified by tooth and preserved in 1:1 anhydrous glycerol/absolute alcohol solution. Citric acid pH 1 was applied to 32 of the slabs for 5 minutes with one of 4 different techniques: 1) immersion; 2) placed with a saturated cotton pellet with no rubbing; 3) placed and burnished with a saturated cotton pellet; or 4) applied with a camel hair brush. The remaining 8 dentin slabs were used as negative control specimens, root-planed and non-acid treated. Following the various treatments, the slabs were fixed, dehydrated, critical point dried, and coated for scanning electron microscopic (SEM) evaluation. Scanning photomicrographs were obtained at 2,000, 6,000, and 40,000 magnifications. The surface characteristics of the treated dentin slabs were evaluated descriptively regarding the degree of fiber exposure; the number of exposed tubules and the surface area occupied by tubule orifices were also measured. Friedman's 2-way analysis for block designs was employed. Results demonstrated that root-planed, non-acid treated specimens had an amorphous, irregular surface which corresponded to a smear layer.(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized trial of occlusal adjustment in the treatment of periodontitis patients.

The purpose of the randomized clinical trial was to test; (1) the influence of occlusal adjustment (OA) in association with periodontal therapy on attachment levels, pocket depth, and tooth mobility, (2) whether OA was of greater significance in non-surgically treated periodontal defects, and (3) whether initial tooth mobility or disease severity had an affect on post-treatment attachment levels following OA. After hygienic-phase therapy, 50 patients received OA/No OA according to random assignment; 22 patients received an OA and 28 were not adjusted. 2 months after OA, either modified Widman flap surgery or scaling and root planing by a periodontist were done according to random assignment within each patient in a split-mouth design. Following active treatment patients were maintained with prophylaxis done every 3 months and scored annually. For the analysis of this two-year data, a repeated measures analysis of variance was performed using attachment level change and pocket depths as outcome indicators. There was significantly greater gain of clinical periodontal attachment in patients who received an OA compared to those who did not. Both the surgically and non-surgically treated sides of the mouth responded similarly to OA. There was no affect of OA on the response in pocket depth, nor did initial tooth mobility or initial periodontal disease severity influence the response to OA.

Response of angina and ischemia to long-term treatment in patients with chronic stable angina: a double-blind randomized individualized dosing trial of nifedipine, propranolol and their combination.

Seventy-four patients with chronic stable mild angina, mild coronary artery disease (83% had one- or two-vessel disease) and normal left ventricular function were studied to measure the response of treadmill exercise performance and painful and silent ischemia in the ambulatory setting to randomly assigned treatment with nifedipine or propranolol and their combination; titration to maximal tolerated dosages was performed in double-blind manner. At 3 months both nifedipine and propranolol reduced the weekly angina rate (p less than 0.05); during treadmill exercise testing, increases (p less than 0.05) were noted in time to angina and total exercise time and decreases in maximal ST depression at the end of exercise. There were no differences between the responses to nifedipine and propranolol and no significant additional changes were seen after another 3 months of therapy. The combination of nifedipine and propranolol reduced the number of patients with angina on exercise treadmill testing from 64% to 38% (p less than 0.05). During ambulatory electrocardiographic monitoring before treatment, there were 1.4 +/- 2.4 (mean +/- SD) episodes/24 h of painful ischemia and a very low silent ischemia frequency: mean 1.1 +/- 2.7 episodes/24 h, mean duration 16 +/- 25 min/24 h. Treatment with propranolol and nifedipine resulted in reduction of episodes and duration of painful and painless ischemia; approximately 77% of patients were free of all ischemic episodes. It is concluded that patients with chronic stable mild angina have a low incidence of silent ischemia. Nifedipine or propranolol alone, titrated to individualized maximally tolerated dosages, are equally effective in long-term control of painful and painless ischemia, anginal episodes and exercise-induced ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of metronidazole on periodontal treatment needs.

Periodontitis, a common cause of tooth loss in adult populations, is an inflammatory response to the overgrowth of anaerobic organisms such as spirochetes and bacteroides and, in some cases, micro-aerophilic organisms in the subgingival plaque. In the present investigation, using a double-blind clinical design, we sought to determine whether 1 week of metronidazole treatment plus debridement of the tooth surfaces was superior to 1 week of placebo treatment plus debridement (positive control) in reducing the subsequent amount of periodontal surgery given to the patients. Thirty-nine patients were randomly assigned to either the metronidazole or placebo (positive control) groups. All patients were given the necessary scaling and root planing and were unsupervised in their usage of the medication. After the completion of this treatment, they were reexamined and it was found that the metronidazole regimen caused a significant reduction in surgical needs of about 5 teeth per patient compared to the positive control (difference before and after treatment 8.3 +/- 6.8 teeth metronidazole versus 2.9 +/- 4.8 positive control, P = 0.007). The difference between groups was maintained during the 2 to 3 years' recall period. Metronidazole had a significant effect on the site specific reduction of spirochetes: 90% of the sites in the metronidazole group versus 64% in the positive-control group had a decrease in the percentage of spirochetes (P less than 0.05). We conclude that systemic metronidazole given 250 mg tid for 7 days in conjunction with debridement of the tooth surfaces can significantly reduce the need for periodontal surgery compared to the standard regimen which included only debridement.