The angular bony defect in the maintenance of the periodontal patient

Residual vertical defects: risk of disease progression, retreatment rates, and cost: a retrospective analysis

OBJECTIVES

This study aimed to explore the relationship between Radiographic Residual Vertical Defects (RVDs) and the progression of periodontitis in patients undergoing periodontal maintenance therapy (PMT).

MATERIALS AND METHODS

Teeth with RVDs were compared to the same contralateral teeth in the same patient. The study investigated the effect of smoking, diabetes, compliance, disease Stage, and Grade, baseline probing depth (PD), periodontal risk score (PRS), baseline pocket closure (PC) (≤ 4 mm), and tooth mobility on disease progression. We calculated the need for retreatment during PMT and its associated cost. Generalized estimation equations and linear and multilevel logistic regression analyses were employed for data analysis.

RESULTS

Each group had 139 teeth, accounting for 80 patients. Although the group with RVDs had similar PD reduction compared to the control teeth, the prevalence of PC at the last follow-up was reduced to half in the RVDs group (odds ratio OR = 0.5; p-value = 0.028), regardless of PC status at the baseline. RVDs were also significant predictors of tooth loss due to periodontitis (TLP), with an OR of 2.28 (p = 0.043). Patients with diabetes, Stage IV, higher mobility, and higher PRS scores had a higher risk of tooth loss due to periodontitis (OR = 4.71, 3.84, 3.64, and 5.97, respectively (P < 0.01). Incidences of sites requiring retreatment were similar in both groups, but the cost of treatment was 30% higher for teeth with RVDs. Grade C had the most significant influence on receiving retreatments (OR = 18.8, p = 0.005).

CONCLUSION

Teeth with RVDs represent a risk indicator for tooth loss compared to identical contralateral teeth with similar PD in the same patient. Teeth with RVD had more risk of pocket opening during follow-up.

CLINICAL RELEVANCE

While teeth with RVDs can be maintained long-term, they have twice the risk of pocket opening and tooth loss due to periodontitis during follow-up. Patients with systemic and local risk factors need to be monitored closely as they are at the highest risk of losing teeth with RVDs. The increased cost of retreatment for teeth with RVDs also has implications in terms of retention versus extraction and replacement.

Molecular profiling of gingival crevicular fluid fails to distinguish between infrabony and suprabony periodontal defects

AIM

To assess the differential molecular profiling of gingival crevicular fluid (GCF) from infrabony and suprabony periodontal defects compared with healthy sites.

MATERIALS AND METHODS

Seventy-five samples from 25 patients with untreated periodontitis stage III-IV were included. Clinical and radiological parameters as well as GCF samples were collected from an infrabony defect, a suprabony defect and a periodontally healthy site per patient. A multiplex bead immunoassay was performed to assess the level of 18 biomarkers associated with inflammation, connective tissue degradation and regeneration/repair.

RESULTS

GCF volume was higher in periodontal sites compared with healthy sites, with no significant difference between infrabony and suprabony defects. Fourteen biomarkers were elevated in infrabony and suprabony sites compared with healthy sites (p < .05). Only interleukin-1α levels were increased in infrabony compared with suprabony sites, whereas there was no difference in probing pocket depth.

CONCLUSIONS

Although the GCF molecular profile clearly differentiates periodontally affected sites from healthy sites, the different architecture between infrabony and suprabony defects is not reflected in GCF biomarker changes.

Minimally Invasive Non-Surgical Technique in the Treatment of Intrabony Defects-A Narrative Review

Intrabony defects occur frequently in periodontitis and represent sites that, if left untreated, are at increased risk for disease progression. Although resective or repair procedures have been used to treat intrabony defects, aiming at their elimination, the treatment of choice is surgical periodontal regeneration. The development of periodontal regeneration in the last 30 years has followed two distinctive, though totally different, paths. The interest of researchers has so far focused on regenerative materials and products on one side, and on novel surgical approaches on the other side. In the area of materials and products, three different regenerative concepts have been explored namely, barrier membranes, bone grafts, and wound healing modifiers/biologics, plus many combinations of the aforementioned. In the area of surgical approaches, clinical innovation in flap design and handling, as well as minimally invasive approaches, has radically changed regenerative surgery. Recently, a minimally invasive non-surgical technique (MINST) for the treatment of intrabony defects was proposed. Initial clinical trials indicated comparable results to the surgical minimally invasive techniques in both clinical and radiographic outcomes. These results support the efficacy of this treatment approach. The aim of this review is to present the evidence on the application of minimally invasive non-surgical techniques and their efficacy in the treatment of intrabony defects.

Enamel matrix derivative as an adjunct to minimally invasive non-surgical treatment of intrabony defects: A randomized clinical trial

AIM

To compare the efficacy of minimally invasive non-surgical technique (MINST) with or without enamel matrix derivative (EMD) in the treatment of intrabony defects ≤7 mm.

MATERIALS AND METHODS

Thirty-six patients were randomly assigned to the two groups. The control group received MINST, while the experimental MINST+EMD. Clinical measurements were recorded at baseline and at 6 and 12 months, and radiographic measurements were made at baseline and 12 months.

RESULTS

All subjects completed the study, 18 in each group. Significant improvements were observed in both groups at 12 months (p < .001) with no differences in mean PD reduction (4.0 ± 1.4 vs. 4.2 ± 1.7 mm), CAL gain (3.5 ± 1.4 vs. 3.4 ± 1.6 mm), and defect resolution (1.9 ± 1.1 vs. 1.8 ± 0.9 mm) for the MINST and the MINST+EMD groups, respectively (p > .05). A trend for greater pocket closure (PD ≤4 mm and no BoP) was achieved with the application of EMD (77.8% vs. 55.6% sites), particularly for sites with baseline PD ≤8 mm (92.3% vs. 69.2% sites), accompanied by an increased number of successful composite outcome results (61.1% vs. 44.4% sites).

CONCLUSIONS

MINST demonstrates significant improvements 12 months after treatment of intrabony defects ≤7 mm. The additional application of EMD does not further improve the mean clinical or radiographic outcomes. This study is registered in ClinicalTrials.gov (NCT03622255).

Periodontal infrabony defects: Systematic review of healing by defect morphology following regenerative surgery

BACKGROUND

It is thought that infrabony defect morphology affects the outcome of periodontal regenerative surgery. However, this has not been systematically investigated.

AIMS

To investigate how well defect morphology is described in papers reporting regenerative therapy of periodontal infrabony defects and to investigate its effect on clinical and radiographic outcomes.

MATERIALS AND METHODS

A search was conducted in 3 electronic databases for publications reporting clinical and radiographic outcomes of periodontal intra-bony defects after regenerative therapy, divided by defect morphology.

RESULTS

The initial search resulted in 4487 papers, reduced to 143 after first and second screening. Fifteen of these publications were suitable for a fixed-effects meta-analysis. Initial defect depth was found to influence radiographic bone gain 12 months post-surgery, while narrower angles and increased number of walls influenced both radiographic bone gain and clinical attachment level (CAL) gain at 12 months. These associations seemed to occur irrespective of biomaterials used. Risk of bias ranged from low to high.

CONCLUSION

Deeper defects with narrower angles and increased number of walls exhibit improved CAL and radiographic bone gain at 12 months post-regenerative surgery. More data are needed about other aspects of defect morphology such as extension to buccal/lingual surfaces.

Baseline probing depth and interproximal sites predict treatment outcomes of non-surgical periodontal therapy

BACKGROUND/PURPOSE

The efficacy of non-surgical periodontal therapy (NSPT) has been well discussed. The aim of this study was to investigate whether the baseline clinical periodontal parameters, radiographic defect angle, and interproximal site predict the treatment outcome of NSPT.

MATERIALS AND METHODS

A total of 39 patients who were diagnosed with generalized chronic periodontitis and met the inclusion criteria were enrolled in this study. All patients received full-mouth periodontal examination by two well-trained periodontists. Clinical periodontal parameters, including probing depth (PD), recession (Rec), and clinical attachment level (CAL), were recorded, and vertical bitewing radiographs were taken as baseline data. Revaluation was performed after 4 weeks of non-surgical periodontal treatment. Pearson's correlation coefficient and multivariate logistic regression were performed to examine the association between favorable treatment outcome (PD reduction ≥ 3 mm) and various clinical parameters.

RESULTS

A significant improvement was observed in PD reduction and CAL gain after NSPT. The radiographic defect angle was strongly correlated with baseline Rec, baseline CAL, and interproximal sites in teeth with a deeper PD. Baseline PD and interproximal sites emerged as significant prediction factors for favorable treatment outcome with a PD reduction of ≥3 mm.

CONCLUSION

Our study is the first to report that distal sites show wider radiographic angles with shallow infrabony defects and that pocket reduction is more obvious at distal sites than at mesial sites. These data provide evidence that baseline PD and interproximal sites may predict the treatment outcome of NSPT.

Factors affecting decision making at reassessment of periodontitis. Part 3: interpretation of clinical findings - local factors

This paper is the third in a four-part series outlining treatment planning at periodontal reassessment. The first article focused on the information that should be gathered at the reassessment appointment. The second article discussed systemic factors that can relate to residual periodontal probing depths. This article outlines local factors that need to be assessed when faced with residual periodontal probing depths. Treatment can involve a range of non-surgical and surgical approaches. A variety of general, practical and local site factors can affect the choice of one option over another in choosing the most predictable treatment option.

Patterns of bone loss around teeth restored with endodontic posts

OBJECTIVES

This retrospective study described the pattern of bone loss around teeth with endodontic posts in periodontitis patients, and compared it with contra-lateral teeth without posts.

MATERIAL AND METHODS

From full-mouth radiographic surveys of 146 periodontitis patients (> or =35 years), 194 roots with endodontic posts and contra-laterals without posts were selected. Upper molars, pre-molars with two posts and roots of lower molars with two posts were excluded. Technical parameters of the post space preparation, endodontic and restorative status were evaluated. The level of alveolar bone measured in millimetre from the cemento-enamel junction (CEJ)/restoration margin and the pattern of bone loss (angular/horizontal) were evaluated on both mesial and distal aspects of roots with posts and contra-laterals, but not on the furcal areas of lower molars.

RESULTS

The distance from the bone level to the CEJ/restoration margin was similar for teeth with posts and contra-laterals. However, teeth with posts had more angular defects mesially (18.8%versus 7.3%) as compared with their contra-laterals without posts. The defects around teeth with posts appeared to be typical in the sense that their apical level approximated the tip of the endodontic post.

CONCLUSION

In periodontitis patients, teeth restored by an endodontic post had angular bony defects on the mesial aspect more frequently in comparison with their contra-laterals.

Stability of treated angular and horizontal bony defects: a retrospective radiographic evaluation in a private periodontal practice

BACKGROUND

This retrospective radiographic evaluation provided a comparative assessment of long-term alterations of alveolar bone levels at sites with angular and horizontal bony defects that underwent open-flap debridement and did not undergo resective or regenerative periodontal therapy.

METHODS

The investigation included 50 patients (27 met inclusion criteria) who had periodontal surgery and periodontal maintenance every 3 to 6 months and who presented with sites demonstrating radiographic angular defects and sites on adjacent or contralateral teeth that demonstrated horizontal bone loss. Subsequent to surgical therapy, alterations in bone levels at the alveolar crest of horizontal defects and at the base of angular defects were evaluated by comparing radiographs from the initial examination to those obtained after a period of periodontal maintenance (6 to 16 years; mean: 8.83 years).

RESULTS

After periodontal therapy, sites with angular and horizontal alveolar bone loss had additional bone loss of 5.56% and 3.88%, respectively.

CONCLUSION

Based on a defining criterion of 10%, the angular and horizontal sites were clinically equivalent with respect to the magnitude of osseous resorption that occurred after periodontal surgery and maintenance.

Disease progression: identification of high-risk groups and individuals for periodontitis

AIMS

While the role of bacteria in the initiation of periodontitis is primary, a range of host-related factors influence the onset, clinical presentation and rate of progression of disease. The objectives of this review are (1) to present evidence for individual predictive factors associated with a patient's susceptibility to progression of periodontitis and (2) to describe the use of prognostic models aimed at identifying high-risk groups and individuals in a clinical setting.

METHODS

Relevant publications in the English language were identified after Medline and PubMed database searches. Because of a paucity of longitudinal studies investigating factors including clinical, demographic, environmental, behavioural, psychosocial, genetic, systemic and microbiologic parameters to identify individuals at risk for disease progression, some association studies were also included in this review.

FINDINGS AND CONCLUSIONS

Cigarette smoking is a strong predictor of progressive periodontitis, the effect of which is dose related. High levels of specific bacteria have been predictive of progressive periodontitis in some studies but not all. Diabetics with poor glycaemic control have an increased risk for progression of periodontitis. The evidence for the effect of a number of putative factors including interleukin-1 genotype, osteoporosis and psychosocial factors is inconclusive and requires further investigation in prospective longitudinal studies. Specific and sensitive diagnostic tests for the identification of individuals susceptible to disease progression are not yet a reality. While factors assessed independently may not be valuable in predicting risk of future attachment loss, the combination of factors in a multifactorial model may be useful in identifying individuals at risk for disease progression. A number of multifactorial models for risk assessment, at a subject level have been developed but require validation in prospective longitudinal studies.

Supportive periodontal care: the effect of periodic subgingival debridement compared with supragingival prophylaxis with respect to clinical outcomes

BACKGROUND

The programme of supportive periodontal care (SPC) is essential to the long-term stability of patients with chronic periodontitis. The clinical strategy for SPC is often determined according to 'clinical needs' of the patient and is thus determined by clinical observation and individual decision-making rather than being based on the best available clinical evidence.

OBJECTIVE

To evaluate the effectiveness of supragingival prophylaxis vs. sub-gingival debridement for SPC following the treatment of chronic periodontitis.

SEARCH STRATEGY

Computerized for Medline and the Cochrane Oral Health Group Specialty Trials Register. Hand searching of the Journals of Clinical Periodontology, Periodontal Research and Periodontology. Reference lists from relevant articles were scanned and the authors of eligible studies were contacted to obtain additional information.

SELECTION CRITERIA

Studies were selected if they were designed as a prospective clinical trial in which patients with chronic periodontitis had followed a programme of SPC, which included at least one of the regimens of interest in part of the mouth, for a minimum of 12 months.

DATA COLLECTION AND ANALYSIS

Information regarding methods, patients, interventions (SPC), outcome measures and results were extracted independently, in duplicate, by two reviewers (P.A.H., G.McC.). Absent data were recorded as such and incomplete data were sought from the researchers wherever possible.

RESULTS

In all, 28 papers were identified by the manual and electronic searches; 11 papers were eligible for inclusion. Only one study reported a direct comparison of the two SPCs of interest. The data were reported as mean changes in probing depth and attachment level between baseline and the 12-month follow-up point. For coronal scaling DeltaPD = 0.59 mm [0.13], DeltaAL = -0.13 mm [0.19]. For subgingival debridement DeltaPD = 0.37 mm [0.15], DeltaAL = -0.14 mm [0.18]. There were no significant differences between the SPC regimens. The weighted mean DeltaPD [95% confidence intervals] for the five additional studies that reported supragingival prophylaxis as the SPC regimen was 1.15 mm [-0.17, 2.38]. The weighted mean DeltaPD [95% confidence intervals] for the four studies that reported subgingival debridement as the SPC regimen was 0.56 mm [0.37, 1.47]. The difference between the SPC treatments for the mean DeltaPD is therefore 0.23 mm. The confidence interval for the combined studies was very wide [0.37, 1.47] and very little additional information is gained unless some strong assumptions are made about the comparability of the populations from which the samples are drawn. Such an assumption was not considered appropriate. The weighted mean DeltaAL [95% confidence intervals] for the six additional studies that reported supragingival prophylaxis as the SPC regimen was 0.18 mm [-0.38, 0.74]. The weighted mean DeltaAL [95% confidence intervals] for the six additional studies that reported supragingival prophylaxis as the SPC regimen was 0.50 mm [0.11, 0.89]. The difference between the SPC treatments for mean DeltaAL is 0.32 mm. The confidence interval [-0.36, 1.00] is very wide and the data from the additional studies provide little extra information than that reported in the one study that compared the treatments directly.

CONCLUSION

It is not possible to make any firm recommendations regarding clinical practice based on the crude meta-analysis and the review of these 11 studies. The best available evidence indicates that SPC regimens of supragingival prophylaxis and subgingival debridement are comparable with respect to the clinical outcomes of probing depth and attachment levels at 12 months post non-surgical treatment.

Effects of proximal vertical destructions on periodontal status and healing in adjacent proximal sites with horizontal destruction

The purpose of the study was to investigate if the presence of vertical destruction in proximal sites influences periodontal status and healing in adjacent sites in the same proximal space without vertical destruction. The investigation was conducted as a retrospective study on a 3-year consecutive referral population of periodontitis-prone patients based on full-mouth oral radiographic examinations, probing pocket depth registrations and plaque scores. The analyses were performed by using regression analyses on a final sample of 1169 (periodontal status) and 1051 (periodontal healing) proximal sites in 163 patients. The relative radiographic attachment level (RRAL) in proximal horizontal sites did not depend on the type of destruction, vertical or horizontal, in the adjacent proximal sites. However, after non-surgical treatment, pocket-depth reduction in proximal sites with horizontal destruction was significantly reduced in the presence of a vertical destruction in the adjacent proximal site compared to the corresponding sites adjacent to a horizontal defect. It was concluded that marginal periodontal healing in proximal sites with horizontal destruction is impaired by the presence of a vertical destruction in the adjacent proximal site.

Factors affecting the healing response of intrabony defects following guided tissue regeneration and access flap surgery

Identification and control of significant factors determining clinical outcomes is of paramount importance to improve expected results of a variety of therapeutic procedures. The aim of this investigation was to identify, with a multivariate approach, factors associated with healing outcomes of 3 periodontal surgical procedures in deep intrabony defects. 45 patients with evidence of deep intrabony defects were randomly assigned to 3 treatment groups: access flap (group C), conventional guided tissue regeneration (GTR) with non-resorbable expanded polytetrafluoroethilene (ePTFE) membranes (group B), and GTR with self supporting membranes combined with the modified papilla preservation technique (group A). In both GTR procedures, membranes were positioned coronal to the interproxymal alveolar crest. Primary outcome variables (i.e., probing attachment level gains at 1 year and the amount of newly formed tissue present at membrane removal) were explained in terms of a series of patient, defect morphology and surgical factors, using a multivariate approach. Highly significant treatment effects were observed, indicating that the 3 tested therapeutic modalities resulted in significant differences in primary outcome variables. Detailed analysis assessing the significance of the tested factors in determining the healing outcomes following each procedure was performed with a stepwise elimination approach of non-significant factors. The results indicated that: (i) the need to create and maintain space should be a key objective of regenerative approaches based upon the principles of guided tissue regeneration; (ii) control of patient's oral hygiene and residual periodontal infection in the oral cavity are strongly associated with clinical outcomes of both regenerative and conventional surgical procedures and should receive proper attention.

Prognostic criteria for the efficiency of non-surgical periodontal therapy in advanced periodontitis

The aim of the study was to find out which clinical, radiographic and microbiological variables can be used as prognostic criteria for the efficiency of the commonly used initial treatment protocol comprising scaling, root planning and instruction on oral hygiene in advanced adult periodontitis. 46 patients (mean age 48 years) with untreated, advanced periodontitis volunteered for the study. The clinical examination included recordings of plaque, gingival and calculus indices, probing pocket depths, bleeding and suppuration after probing, probing attachment levels and furcation involvements. Infrabony and furcation lesions were assessed from panoramic radiographs. Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were cultured from the deepest, most inflamed periodontal Pockets, from surface of the tongue and from saliva. 3 months after the completion of non-surgical treatment comprising meticulous scaling and root planing and instruction on oral hygiene, the healing was assessed clinically, and 13 patients were assigned to a maintenance care programme (MC) and 33 to further treatment procedures (FT). Evaluation of the baseline clinical and radiographic data showed a significantly higher %s of > or = 6 mm deep periodontal pockets, surfaces with suppuration, and sites with subgingival calculus, as well as higher numbers of infrabony lesions, in FT-patients than in MC-patients. Subgingival A. actinomycetemcomitans was isolated at baseline in 55% of the FT-patients and in 38% of the MC-patients, and P. gingivalis in 27% and 23%, respectively. A. actinomycetemcomitans was eradicated by non-surgical treatment from only one patient. P. gingivalis was detected in 15% of the patients in both groups after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Utility of radiographic crestal lamina dura for predicting periodontitis disease-activity

The relationship between radiographic crestal lamina dura and periodontitis disease-activity was studied longitudinally in 51 treated adult patients on a systematic 3-month maintenance program. The presence or absence of crestal lamina dura at 1809 interproximal sites was scored from periapical and bitewing radiographs taken at baseline of a 36-month maintenance care period. Semi-annual clinical evaluations by 2 independent examiners were carried out on each patient, with disease recurrence defined as sites revealing a > or = 3 mm increase in probing depth from baseline, or a > or = 2 mm increase in probing depth together with a > or = 2 mm loss of relative attachment level from an occlusal reference stent. Over the 36-month study period, 23 (45%) patients exhibited disease recurrence at 55 (3%) interproximal tooth sites scored for baseline crestal lamina dura. Absence of detectable baseline crestal lamina dura yielded high sensitivity (87-100%), but low specificity (17%) and low positive predictive values (0.8-3.2%), for localized periodontitis recurrence. In contrast, no sites exhibiting an intact baseline crestal lamina dura demonstrated periodontitis recurrence up to 24 months from baseline (100% positive predictive values). Presence of radiographic crestal lamina dura was positively associated with clinical periodontal stability (summary odds ratio for sites = 2.6, P = 0.0004), and negatively associated with periodontitis recurrence (summary odds ratio for sites = 0.4, P = 0.0004), for the 36-month study period. Evaluation of radiographic crestal lamina dura status appears valuable for assessing the risk of periodontitis disease-activity at inter-proximal tooth sites in patients on maintenance care programs.

The angular bony defect as indicator of further alveolar bone loss

The aim of the present retrospective study was to evaluate alterations of the alveolar bone level over a 10-year period at tooth sites with "angular" and "even" patterns of bone loss, in subjects who were not exposed to systematic periodontal therapy. A further objective was to evaluate whether the presence of an angular defect can serve as a predictor of additional bone loss. 201 subjects in ages 25-70 years were examined radiographically on 2 occasions 10 years apart. 194 were dentate on the 2nd examination. The radiographic bone height at the mesial and distal aspect of all teeth was assessed by measuring the distance between the cemento-enamel junction and the bone crest. The morphologic pattern of alveolar bone loss at baseline was assessed for each tooth site. Angular defects were classified as degree 1, 2 and 3, according to increasing defect depth. The change in periodontal bone height over the 10-year period was calculated for each site. The results demonstrated an increased frequency of tooth loss among teeth showing presence of an angular bony defect at baseline; whereas 13% of the teeth with an even pattern of bone loss were lost between the 2 examinations, this proportion was 22%, 46% and 68% for teeth with an angular defect of degree 1, degree 2 and degree 3, respectively. Longitudinal bone loss of greater than or equal to 2 mm occurred more often among sites showing an angular defect when compared to sites with an even alveolar bone morphology.(ABSTRACT TRUNCATED AT 250 WORDS)

One-wall proximal defects: pretreatment characteristics and bone response following flap curettage

Several characteristics of 53 infrabony defects were compared with changes in bone height, following treatment by flap-curettage and regular maintenance. The mean post-surgical interval was 11.4 years. Proximal angular defects from mandibular posterior teeth comprised the study population. Changes in bone height following therapy were compared with the pre-treatment bone loss, tooth-bone angle, and inter-radicular width. The influence of the post-surgical duration on these factors was also evaluated. Bone height was examined at both the deep and shallow sides of each proximal defect. Data were collected from enlarged tracings of pre- and post-treatment radiographs. Gain or loss of bone was established at greater than 2 SD of the measurement error as determined by replicate calibration trials. Deep-side sites which gained bone exhibited the most pretreatment bone loss at a mean of 57.1%. These sites also exhibited a mean tooth-bone angle of 31.9 degrees and a mean inter-radicular width of 3.1 mm. Gaining sites were those with longer post-surgical durations. Deep-side sites that lost bone following therapy had a mean pre-treatment bone loss of 43.6%, a mean tooth-bone angle of 50.3 degrees, and a mean interradicular width of 2.9 mm. Losing sites were those with shorter post-surgical durations. The majority of deep-side sites with less than 55% pretreatment bone loss remained unchanged. Shallow-side sites which gained bone following treatment had a greater mean pretreatment bone loss and a smaller tooth-bone angle than losing sites.

Relationship between the radiographic periodontal defect angle and healing after treatment

This study radiographically evaluated the correlation between the changes in alveolar bone level occurring in bony defects after periodontal therapy and the corresponding pretreatment defect angles. The defect angle was defined by the bony defect surface and the root surface. The changes were determined from identically exposed and processed radiographs obtained just prior to surgery and 15 to 18 months later. The defect angle was clearly correlated to the radiographic changes in alveolar bone level. Most defects with an angle less than 45 degree showed a gain of bone while defects with the largest defect angles showed a loss. In addition, defects on root surfaces without furcations showed better healing than defects associated with furcations.