Histometric evaluation of periodontal surgery I. The modified Widman flap procedure

Abstract The present investigation was performed in the Rhesus monkey to determine the effect of the modified Widman flap procedure on the level of the connective tissue attachment and supporting alveolar bone. Two adult male Rhesus monkeys were used. Eighteen contralateral pairs of periodontal pockets were produced in a standardized manner. Surgical treatment of the pockets was performed around experimental teeth and the contra-lateral teeth were used as the unoperated controls. Twelve months following treatment the animals were sacrificed and histological sections obtained. Using the cemento-enamel junction (CEJ) as a fixed reference point, linear measurements along the. root surface were made to the most apical cells of the junctional epithelium (JE), to the crest of the inter-proximal alveolar bone (CR), and to the apical extent of angular bony defects (AAD). These measurements from operated and unoperated pockets were then compared. The data revealed that treatment of periodontal pockets using the modified Widman flap procedure produced no gain in connective tissue attachment and no increase in crestal bone height. In angular bony defects a certain degree “bone fill” was noted. This bone repair was never accompanied by new connective tissue attachment.     

Periodontal surgery in plaque-infected dentitions

A clinical trial was performed to study the result of periodontal treatment following different modes of periodontal surgery in patients not recalled for maintenance care. The material consisted of 25 patients distributed into 5 groups. Following an initial examination, all patients underwent presurgical treatment including case presentation and instruction in oral hygiene measures. This instruction was given once. The various patient groups were then subjected to one of the following surgical procedures: 1) the apically repositioned flap operation including elimination of bony defects 2) the apically repositioned flap operation including curettage of bony defects but without removal of bone 3) the "Widman flap" technique including elimination of bony defects 4) the "Widman flap" technique including curettage of bony defects but without removal of bone 5) gingivectomy including curettage of bony defects but without removal of bone. Six, 12 and 24 months after completion of the treatment, the patients were recalled for assessment of their oral hygiene standard and periodontal conditions. The results showed that case presentation and oral hygiene instruction given once, only temporarily improved the patient's oral hygiene habits. Renewed accumulation of plaque in the operated areas resulted in recurrence of periodontal disease including a significant further loss of attachment. All five different techniques for surgical pocket elimination were equally ineffective in preventing recurrence of destructive periodontitis.     

The healing potential of the periodontal tissues following different techniques of periodontal surgery in plaque-free dentitions

A clinical trial was undertaken to study the healing capacity of the periodontal tissues following different modes of periodontal surgery in patients whose oral hygiene was professionally maintained at an optimal level. Fifty patients, distributed into five groups, participated in the study. Following an initial examination and presurgical treatment, the various patient groups were subjected to one of the following surgical procedures: 1) the apically repositioned flap operation including elimination of bony defects, 2) the apically repositioned flap operation including curettage of the bony defects but without removal of bone, 3) the "Widman flap" technique including elimination of bony defects, 4) the "Widman flap" technique including curettage of the bony defects but without removal of bone, 5) gingivectomy including curettage of the bony defects but without removal of bone. After surgery, all patients received oral hygiene instruction and professional cleaning of the teeth once every 2 weeks during a 2-year period. The results showed that periodontal disease can be cured and further destruction of the periodontal tissues avoided irrespective of the surgical technique utilized for pocket elimination. Different surgical techniques, however, promoted varying degrees of regeneration of the supporting tissues. The most favourable healing was obtained when resection of bone was avoided and when complete coverage of the alveolar bone was ensured.     

A retrospective radiographic outcome assessment study of intra-bony defects treated by osseous surgery or by bone graft procedures

BACKGROUND: Intra-bony defects remain a significant therapeutic problem in periodontal therapy. Various non-surgical and surgical treatment modalities are being used. The long-term stability following treatment of intra-bony defects is poorly documented. OBJECTIVES: To assess changes in intra-bony defects after either osseous surgery or open flap debridement in combination with grafting procedures with demineralized freeze-dried bone allografts (DFDBA). METHOD: Pre- and post-surgical computer digitized images of intra-oral radiographs from 60 patients who had received periodontal surgery to manage intrabony defects were analyzed by linear measurements. RESULTS: 36 patients were treated with osseous surgery and 24 had received flap procedures and grafting with DFDBA. Post-surgical radiographs were obtained on average after 4.8 years (SD+/-2.8) and after 9.6 years (SD+/-3.6). A minor mean bone fill of 0.0 mm (SD+/-0.8) for osseous surgery sites and 0.5 mm (SD+/-0.9) for DFDBA sites, was noticed, but this gain was within the margin of measurement errors. Osseous surgery and modified Widman flap procedures with DFDBA resulted in crestal resorption, on average 1.7 mm (SD+/-1.5) and 1.5 mm (SD+/-1.5) and remaining mean defect depth of 2.0 mm (SD+/-1.4) and 2.5 mm (SD+/-1.6), respectively. CONCLUSIONS: Bone changes following bone graft procedures with DFDBA did not differ from those following osseous surgery, and neither procedure resulted in defect resolution with bone fill. It was also concluded that over the study period, stable treatment results were obtained as a result of both osseous surgery and modified Widman flap procedures with adjunct DFDBA.     

The effect of root planing as compared to that of surgical treatment

Abstract This study was undertaken in order to evaluate the effect of root planing as compared to that of surgical periodontal treatment in patients with advanced periodontal disease. 17 patients with advanced periodontal disease participated in the study. After the initial examination, the teeth were scaled and the patients were given instruction in performing proper oral hygiene. The hygienic phase for the individual patient was continued until less than 20% of the tooth surfaces demonstrated plaque at 2 succeeding appointments. After re-assessment of the periodontal status, 1 side in both the maxilla and mandible was treated with modified Widman flap surgery. In I of the remaining quadrants, in the maxilla or mandible, reverse bevel flap surgery was used. Bone contouring was not performed in any of the surgical procedures. The last quadrant was subjected to meticulous root planing under local anesthesia. Subsequently, the patients were recalled every second week for professional tooth cleaning. The periodontal status of each patient was assessed 3 and 6 months following treatment. Root planing resulted in considerable reduction in pocket depth, although more shallow pockets were obtained following modified Widman flap and reverse bevel flap surgery. Clinical gain of attachment was obtained following all 3 modalities, but root planing resulted in slightly more gain of attachment than the 2 surgical procedures.     

Sounding depth measurements: a method for evaluating various surgical techniques

Fourteen patients undergoing periodontal treatment for moderate to severe adult-type periodontitis were included in the study. Seven patients (a total of 210 sites) were treated with modified Widman flap surgery while the other 7 patients (the same number of sites) were treated with apically-positioned flap surgery. The 2 modalities were compared using sounding depth measurements before and immediately after surgery. The mean sounding depth decreased from 4.89 mm to 3.42 mm in the modified Widman flap group, compared to a drop from 4.77 mm to 2.46 mm in the apically-positioned flap group. Neither of these procedures resulted in the total eradication of all periodontal pockets. The final outcome of modified Widman flap surgery may, at times, result in zero sounding depth (placement of the flap at the crest of the bone); on the other hand, very often the flap was placed far supra-crestally in an intended apically-positioned flap procedure. This lack of consistency between intended and actual flap placement would suggest that studies which try to compare different treatment modalities using a flap approach should include sounding depth measurements immediately post-surgery. This is needed to assure that the intended procedure has actually been carried out.     

Gingivectomy versus flap surgery: the effect of the treatment of infrabony defects. A clinical and radiographic study.

The aim of this paper was to compare the short-term results of gingivectomy (GV) and modified Widman flap (MWF) surgery in the treatment of infrabony defects. 14 patients with 68 bilateral infrabony defects were selected. At baseline, and 3 and 6 months postoperatively, assessments of oral hygiene, gingival conditions, bleeding on probing, probing pocket depth and attachment level, were recorded. Conventional radiograps were obtained in a way that assured a reproducible projection geometry. In a split-mouth design, one jaw quadrant was randomly treated with GV, while the contralateral with a MWF. The changes of the bone tissue were assessed by means of conventional and subtraction images by 2 observers. The interobserver agreement of the conventional and subtraction technique was studied. The majority of the sites demonstrated a significant improvement in gingival conditions and a reduction in bleeding. For both treatments, probing depths were reduced by an average of 3 mm, while a mean of 1.22-1.35 mm of probing attachment gain was obtained. The GV resulted in slightly more gingival recession (1.90 mm) than the MWF (1.60 mm). The radiographic examination demonstrated gain of bone in 7 defects treated with GV and in 9 defects treated with MWF. This study demonstrated that pockets associated with infrabony defects can be successfully treated by both treatment modalities. Furthermore, bone gain can occur after treatment but not in a predictable manner.     

The effect of systematic plaque control on bone regeneration in infrabony pockets

Abstract A clinical trial was undertaken to test the hypothesis that periodontitis can be cured and that bone regeneration occurs in infrabony pockets in patients maintained on an optimal standard of oral hygiene. The material comprised 24 patients with advanced periodontal disease. After an initial examination, the patients were randomly distributed into one test group and one control group. All the patients were given instruction and practice in a proper oral hygiene technique, and then subjected to periodontal surgery using the modified Widman flap procedure. Following treatment, during a 2-year period the patients of the test group were recalled once every second week for professional tooth cleaning. The control patients were recalled once every 12 months for prophylaxis. The results showed that all osseous defects of the patients of the test group were refilled with bone. The control patients, on the other hand, could not maintain a high standard of oral hygiene, and exhibited a progressive deterioration of the periodontal tissues during the postsurgical observation time.     

Improved periodontal conditions following therapy

The aim of the present clinical trial was to evaluate the effect of different modes of periodontal therapy on patients with moderately advanced periodontal disease and to express the findings in terms of probing pocket depth and attachment level alterations at periodontal sites with different initial probing depths. The material consisted of 16 patients, 35-65 years of age. Following a Baseline examination including assessments of oral hygiene status, gingival conditions, probing pocket depths and probing attachment levels, the patients were subjected to periodontal treatment. A "split-mouth" design approach of therapy was used and the jaw quadrants were randomly selected for the following different treatment procedures: (1) scaling and root planning, (2) scaling and root planing in conjunction with a gingivectomy procedure, (3) scaling and root planing in conjunction with an apically repositioned flap procedure without bone recontouring, (4) scaling and root planing in conjunction with an apically repositioned flap procedure including bone recontouring, (5) scaling and root planing in conjunction with a modified Widman flap procedure without bone recontouring and (6) scaling and root planing in conjunction with a modified Widman flap procedure including bone recontouring. The patients were following active treatment enrolled in a supervised maintenance care program including "professional tooth cleaning" once every 2 weeks during a 6-month period of healing, after which a final examination was performed. The investigation demonstrated that active therapy including meticulous subgingival debridement resulted in a low frequency of gingival sites which bled on probing, a high frequency of sites with shallow pockets (less than 4 mm) and the disappearance of pockets with a probing depth of greater than 6 mm. Between the Baseline examination and the 6-month re-examination, the probing attachment level for initially shallow pockets remained basically unaltered, but with a tendency of a minor apical shift. This occurred in all 6 treatment groups. For sites with initial probing depths of 4-6 mm and greater than 6 mm, there was in all groups some gain of probing attachment. This gain was most pronounced in the initially deeper (greater than 6 mm) pockets. With the use of regression analysis, the "critical probing depth" (CPD) value (i.e. the initial probing depth value below which loss of attachment occurred as a result of treatment and above which gain of probing attachment level resulted) was calculated for each of the 6 methods of treatment used. A comparison of the CPD-values between the 6 treatment groups did not reveal any major differences.     

4 modalities of periodontal treatment compared over 5 years

The purpose of the present study was to assess in a clinical trial over 5 years the results following 4 different modalities of periodontal therapy (pocket elimination or reduction surgery, modified Widman flap surgery, subgingival curettage, and scaling and rool planing). 90 patients were treated. The treatment methods were applied on a random basis to each of the 4 quadrants of the dentition. The patients were given professional tooth cleaning and oral hygiene instructions every 3 months. Pocket depth and attachment levels were scored once a year. 72 patients completed the 5 years of observation. Both patient means for pocket depth and attachment level as well as % distribution of sites with loss of attachment greater than or equal to 2 mm and greater than or equal to 3 mm were compared. For 1-3 mm probing depth, scaling and root planing, as well as subgingival curettage led to significantly less attachment loss than pocket elimination and modified Widman flap surgery. For 4-6 mm pockets, scaling and root planing and curettage had better attachment results than pocket elimination surgery. For the 7-12 mm pockets, there was no statistically significant difference among the results following the various procedures.     

Bone density changes after 1 year in periodontal lesions treated surgically with or without ePTFE membrane placement

Abstract The present study was designed to quantitatively assess radiographic changes in alveolar bone density in intrabony defects treated with expanded polytetrafluorethylene membranes (ePTFE) or by conventional flap surgery alone. 15 patients with 2 periodontal defects of comparable morphology which could be depicted on a single radiograph made up the test panel. Standardized radiographs of the periodontal defects were taken immediately prior to surgery and 12 months later. The 2 defects were treated simultaneously using the modified Widman flap procedure and prepared for membrane placement. Then one of the lesions was randomly assigned for treatment with the membrane. All radiographs and surgical procedures were managed by one person. The radiographs were assessed by another person according to a blind design. Periodontal defects treated with ePTFE membranes (test), and sites treated by conventional flap procedures (control) were then analyzed using a computerized image analysis program. In 8 patients, the test site outcome was better than the outcome in the control site. 6 of the control sites indicated increased bone density, while 7 sites showed decreased values, and 2 sites were unchanged. The corresponding values from the test sites were 5, 6 and 4, respectively. In the present controlled clinical study, the use of an ePTFE membrane to cover the opening of a vertical bone defects during periodontal surgery did not predictably increase the bone density of the defects.     

Healing following surgical and non-surgical treatment of juvenile periodontitis

The patient sample used in the present study comprised 16 young individuals who were referred for treatment of advanced periodontal disease. Based upon the age of the patients and the location of the diseased sites, the patients were divided into 2 groups; a juvenile periodontitis group (JP) and a post-juvenile periodontitis group (post-JP). The patients in the JP group had periodontal lesions only at first molars and incisors. All 16 subjects were in excellent general health and none had been treated with antibiotics during a period of at least 12 months prior to the 1st examination. At a baseline examination and 6, 24 and 60 months after active therapy, the diseased sites were examined regarding plaque, gingivitis, probing pocket depths, probing attachment level, recession of the gingival margin and marginal alveolar bone level. Following a case presentation and instruction in proper oral hygiene measures, the 16 subjects were subjected to periodontal treatment, utilizing a split mouth design. By random selection, the diseased sites in one side of the jaws were treated by scaling and root planing in conjunction with a "modified Widman flap" procedure, while in the contralateral jaw quadrants treatment was restricted to scaling and root planing. During the 1st 6 months following active therapy, the patients were subjected to professional tooth cleaning once every 4 weeks. Subsequently, the interval between the recall appointment was 3 months. 2 years after treatment, this maintenance care program was terminated. A final examination was performed 5 years after therapy. None of the patients involved in the trial received antibiotic treatment during the 5 years of observation. The findings of the present study revealed that the response of the periodontal tissues to therapy, both in the JP and the post-JP group of patients, was almost identical to that found for similar types of treatment in patients with adult periodontitis. The re-examinations performed after 6, 24 and 60 months following active therapy of JP and post-JP lesions revealed that excision of the granulation tissue in conjunction with flap elevation did not enhance the degree of probing pocket depth reduction, probing attachment gain and bone fill that occurred following meticulous root surface instrumentation.     

Healing following surgical non-surgical treatment of periodontal disease

Abstract A clinical trial was undertaken to study the effect of one surgical and one non-surgical treatment modality in patients with advanced periodontal disease. Fifteen patients were selected for the study. Following a Baseline examination comprising assessments of oral hygiene status, gingival conditions, probing depths and attachment levels, all participants were subjected to treatment. In each patient, scaling and root planing were carried out in conjunction with the modified Widman flap procedure in two jaw quadrants while in the contralateral quadrants the treatment was restricted to scaling and root planing. During the phase of active treatment, i.e. the period between the first and last operation, and for the subsequent 6 months of healing, the patients were subjected to “professional toothcleaning” once every 2 weeks. From this time until the end of the trial which was 24 months after active treatment, the patients were recalled for prophylaxis once every 3 months. Reexaminations were performed 6, 12 and 24 months after the completion of active treatment. The results demonstrated that scaling and root planing used alone were almost equally effective as their use in combination with the modified Widman flap procedure in establishing clinically healthy gingiva and in preventing further loss of attachment. Both treatment modalities prevented recurrence of periodontal disease for the 24 months of observation. The analysis of the probing depth data revealed that both methods of treatment resulted in a high frequency of probing depths of <4 mm. The probing depth reduction was more pronounced in initially deep than in initially shallow pockets and, for initially deep pockets, more marked in sites subjected to surgery than in sites exposed to scaling and root planing alone. The measurements also showed that sites with initially deep pockets exhibited more pronounced gain of clinical attachment than sites with initially shallow pockets. Significant loss of attachment did not occur in sites treated with scaling and root planing alone while attachment loss was found following Widman flap surgery in sites with initial probing depth of <4 mm.     

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.     

Long-term effect of surgical and non-surgical periodontal treatment. A 5-year clinical study

The aim of the present study was to evaluate the long-term (5 yr.) effect of surgical and non-surgical periodontal treatment. 16 patients with advanced periodontal disease participated in the study- All patients were subjected to initial treatment comprising supra- and subgingival scaling and instruction in performing proper oral hygiene. Modified Widman flap surgery was always employed in a quadrant in both the maxilla and mandible. Reverse bevel flap surgery or root planing under local anesthesia were used in the contralteral quadrants. During the 1st 2 wk after surgery or root planing the patients rinsed twice daily with 0.2% chlorhexidine digluconate They were then recalled for professional tooth cleaning once every 2nd wk for the 1st yr. every 3rd month during the 2nd yr, and every 6th month during the last 3 yr. Subgingival scaling was performed at each recall appointment during the last 4 yr.
Surgical as well as non-surgical treatment resulted in a considerable reduction in probing pocket depth which was maintained during the 5-yr observation period. A small gain of probing attachment (0.0-0.4 mm) was assessed 3 months after treatment for all procedures, but after 5 yr a small loss of attachment (0.0-0.2 mm) bad occurred in surgically treated areas, whereas a gain of 0.3 mm was maintained in the areas treated with root planing.
The changes in bone level were minute following both surgical and non-surgical treatment. Less than 5% of the tooth surfaces exhibited a loss of probing attachment of more than 2 mm or a loss of alveolar bone of 15% or more of the "normal" bone height alter 5 yr. The number of deteriorating sites in each individual did not correlate with the level of self-performed oral hygiene.     

Clinical and histological characteristics of lyophilized allogenic dura mater in periodontal bony defects in humans

Abstract This clinical and histological study investigated the use of lyophilized, allogenic dura mater (Lyodura ®) as a periodontal implant material in interdental bony defects (2-wall lesions) in humans. For 23 defects in 8 subjects a modified Widman flap was raised, curettage performed and the defects bridged with the implant. The same procedure, without Lyodura implantation, was performed on 23 contralateral teeth. By a standardized method, involving the use of a removable stent, the following clinical measurements were recorded after 24 and 48 weeks: the probing attachment level, the probing bone level, the probing pocket depth and the labial and interdental gingival recession. For the histological study 5 additional, interdental craters arid 5 control defects were treated as in the clinical study. They were block-sectioned after 1,2,6,12 and 24 weeks and processed in the usual manner for routine examination by light and polarization microscopy. From the clinical study it could be concluded that, in absolute values, only the experimental side showed a significant gain in probing attachment level and a greater reduction of the probing pocket depth. In percentage values the labial gingival recession was significantly lower and the bone formation significantly more pronounced on the experimental side. The histological examination showed that the implant remodelled completely without rejection phenomena. It was replaced gradually, after enzymatic breakdown, by the host's own collagen through the action of invading fibroblasts. Bone formation occurred along but never in the implant. The implant material seems to act as a barrier against epithelial downgrowth and infiltration of inflammatory cells.     

Longitudinal therapeutic effects on the periodontal attachment level and pocketdepth in beagle dogs

Thirteen healthy Beagles, 3 1/2–5 years of age with moderate to advanced periodontal discase received a thorough scaling and prophylasis followed by four weeks of daily tooth cleaning. After one month, each of the fourposterior quadrants of each dog was subjected to one of the following treatments: 1) subgingival curettage, 2) modified Widman flap surgery with root planing, 3) apically repositioned flap and bone surgery for pocket elimination and 4) scaling and root planing as a control. Toothbrushings was carried out daily. In addition, every 14 days the dogs received a rubber cup and pumice prophylaxis throughout the entire length of the study. At the baseline, 1, 6, 12, 24 and 36 months following treatment, oral hygiene and gingival health were scored and the level of periodontal attachment and pocket depth were measured. The results at one Month suggested an increase in attachment levels which was grater after scaling or subgingival curettage than after flap procedures. Up to 36 months, the established attachment levels were maintained for all treatment groups and no significant difference was found between any of the treatments and the scaled controls. However, in advanced periodontal lesion attachment levels were not maintaned with scaling alone.
The present study has shown that the more conservative approaches to the treatment of periodontal disease such as subgingival curettage and Widman flap surgery may be as effective in maintaining clincal attachment levels as elaborate surgical procedures involving osteoectomy.     

A report of laser-assisted modified Widman flap for periodontal regeneration: Clinical and radiographic evaluation

Periodontitis is a relatively common disease. Various therapies have been recommended for its treatment which includes nonsurgical, antimicrobial, and surgical therapy. In recent years lasers have been used for all the three above-mentioned purposes. Lasers have been applied for hard and soft tissue debridement, contouring as well as the bacterial load reduction in the pocket. Here we present a case report of chronic periodontitis treated with the help of a new technique, laser-assisted modified Widman flap (LAMWF). The surgical procedure followed with a 980 nm diode laser has been described. The present case report resulted in significant pocket depth reduction, attachment gain, and radiographic evidence of bone fill. The laser-assisted modified Widman flap provided excellent results without complications and high patient as well as clinician satisfaction.     

Short term results of three modalities of periodontal treatment.

Short term data were obtained from 74 patients who recieved comprehensive periodontal treatment using a split mouth approach to test three variables; subgingival curettage, pocket elimination surgery, and modified Widman flap procedure. The patients initially had an average interproximal loss of attachment of 3.2 mm and an average interproximal pocket depth of 3.9 mm. Evaluation of the data indicate that after 4 to 6 weeks: 1. All three surgical procedures reduce pocket depths. In order of effectiveness they are: pocket elimination surgery, modified Widman flap, and subgingival curettage. 2. Pocket elimination surgery reduces pockets more than subgingival curettage on the buccal, lingual and interproximal, and more than the modified Widman flap on the lingual. The modified Widman flap procedure reduces pockets more interproximally than subgingival curettage. 3. Subgingival curettage results in a gain of attachment interproximally, and on the lingual side, while the modified Widman flap resulted in a gain of attachment interproximally only. 4 Pocket elimination surgery resulted in a loss of attachment buccally. 5 Subgingival curettage results in a more favorable postoperative attachment level on all surfaces than did pocket elimination surgery.     

"Critical probing depths" in periodontal therapy

Abstract The present investigation was carried out on 15 individuals who were referred for treatment of moderately advanced periodontal disease. All patients were first subjected to a Baseline examination comprising assessment of oral hygiene and gingival conditions, probing depths and attachment levels. Following case presentation and instructions in oral hygiene measures, the patients were given periodontal treatment utilizing a split mouth design. In one side of the jaw scaling and root planing were performed in conjunction with a modified Widman flap procedure while in the contralateral jaw quadrants the treatment was restricted to scaling and root planing only. The period from initial treatment to 6 months after treatment was considered to be the Healing phase and from 6–24 months after treatment the maintenance phase. During the healing phase the patients were recalled for professional tooth cleaning once every 2 weeks. During the maintenance phase the interval between the recall appointments was extended to 3 months. Reexaminations were carried out 6, 12 and 24 months after the completion of active treatment. The results revealed that treatment resulted in loss of clinical attachment in sites with initially shallow pockets, while sites with initially deep pockets gained clinical attachment. With the use of regression analysis “critical probing depths” were calculated for the two methods of treatment used. It was found that the critical probing depth value for scaling and root planing was significantly smaller than the corresponding value for scaling and root planing used in combination with modified Widman flap surgery (2.9 vs 4.2 mm). In addition, the surgical modality of therapy resulted in more attachment loss than the non-surgical approach when used in sites with initially shallow pockets. On the other hand, in sites with initial probing depths above the critical probing depth value more gain of clinical attachment occurred following Widman flap surgery than following scaling and root planing. The data obtained from the reexaminations 12 and 24 months after active treatment demonstrated that the probing depths and the attachment levels obtained following active therapy and healing were maintained more or less unchanged during a maintenance care period which involved careful prophylaxis once every 3 months. However, the data also disclosed that the level of oral hygiene maintained by the patients during healing and maintenance was more critical for the resulting probing depths and attachment levels than the mode of initial therapy used. Thus, sites which during the maintenance period were found to be free from supragingival plaque were associated with shallow pockets and maintained attachment levels. In contrast, sites which harboured plaque exhibited increasing probing depths and further attachment loss.