REDEFINING THE BIOLOGIC WIDTH IN SEVERE,GENERALIZED, CHRONIC PERIODONTITIS:IMPLICATIONS FOR THERAPY

M. John Novak, Huda M. Albather, and John M. Close. J Periodontol • October 2008. Volume 79 • Number 10

Presenter: Dr. Superna Tiwari

INTRODUCTION

The dentogingival junction to the tooth surface is composed of:

a fibrous, supra-crestal connective tissue attachment and

an epithelial attachment (junctional epithelium), and its dimensions have been delineated from autopsy jaw specimens (Fig. 1)(1,2).

Figure 1.A bucco-lingual histologic specimen of a healthy periodontium showing the components of the dentogingival junction or BW. BW is composed of the junctional epithelium (epithelial attachment) and the supracrestal connective tissue attachment. E = enamel; D = dentin; AC = alveolar crest.

The supra-crestal soft tissue attachment of the periodontal tissues to the tooth/root surface has been termed the ‘‘biologic width’’ (BW) and was introduced as an important concept in Periodontics and restorative dentistry(3).

The histologic dimensions of the BW were comprehensively evaluated on teeth from autopsy specimens of subjects 19 to 50 years of age;

these dimensions varied considerably with age and level of apical migration of the epithelial attachment(2).

Concern has been expressed that the mean values obtained from these studies do not truly reflect the variability that exists in the dimensions of the dentogingival junction(4).

In addition, it was suggested that BW measurements taken from the tissues of a healthy periodontium should not be extrapolated for use in pathologic situations(4).

However, to the best of our knowledge, no studies have been done on BW measurements in animals or humans with clinically diagnosed periodontitis or in subjects with the more aggressive forms of disease

The progression of periodontal destruction is generally considered to be chronic in nature and slowly progressing.

However, under certain circumstances disease progression may be more aggressive, resulting in severe bone and attachment loss at an early age.

More severe disease has been observed when the host bacterial interaction and subsequent pathologic changes in the periodontal tissues have been impacted by environmental and/or acquired risk factors, such as in smokers and patients with systemic conditions and in certain individuals who express an altered inflammatory genotype(5).

It has been believed for many years that the distance from the most apical extent of subgingival calculus or plaque to the crest of the alveolar bone remains generally constant, with mean values of 1.94 to 1.97 mm(1,6).

An average value of 2.04 mm for the BW, the distance from the most coronal extent of the epithelial attachment to the crest of the alveolar bone, is considered to be the norm for most patients and most teeth, although significant variations can occur, especially in the length of the epithelial attachment(2,4).

More than 20 years ago, we reported that the supra-crestal connective tissue attachment is an important, but variable, component of the periodontal support that may provide periodontal stability to teeth that lack alveolar bone support as well as providing an unusually large BW(7).

More recently, we observed in studies of young adults with severe generalized periodontitis that the most coronal level of clinical attachment does not always relate to the crest of the alveolar bone in a manner that is consistent with previous measures of the BW (Fig. 2).

Because considerable variability has been shown to exist in the dimensions of the BW in cross-sectional studies(1,2) of autopsy materials with no overt periodontal pathology,

A) The clinical and radiographic appearance of a subject with severe, generalized, chronic periodontitis

B) Clinical and radiographic appearance of a deep pocket and significant attachment and bone loss on the mesial surface of tooth #8 immediately adjacent to a shallow pocket associated with significant bone loss on the mesial surface of tooth #9 and an extended BW

Figure 2.Similar clinical (C) and radiographic (D) appearances of a deep pocket with significant attachment loss on the distal surface of tooth #28 adjacent to a shallow pocket with minimal clinical attachment loss on the mesial surface of tooth #29 and an extended BW.

The purpose of this study was to determine whether previously observed norms in the BW apply in a previously untreated population with severe generalized periodontitis.

The importance of understanding the variations in BW that may occur with periodontal pathology may impact our approach to surgical intervention if conserving the existing periodontal attachment is a clinical priority.

MATERIALS AND METHODS

The baseline clinical measurements and radiographs, previously gathered from 28 male and female subjects as part of a

longitudinal intervention study at the University of Pittsburgh in 2000, were used for this cross-sectional study of the dimensions of the clinical BW(8).

Inclusion criterionAll consenting subjects were ≤ 45years of age (range: 29 to 45 years) and

were diagnosed as having severe, generalized, chronic periodontitis using recently described criteria(9).

Eligible subjects had to have ≥20 teeth with >30% of measured sites with ≥ 5mm clinical attachment loss, be in good health, and be willing to participate in the study.

Exclusion criterion

Subjects were excluded from participating in the study if

they had received any non-surgical periodontal treatment or antibiotic therapy in the 3 months prior to the screening appointment or

had undergone periodontal surgery in the 12 months prior to screening.

Subjects were also excluded if they needed antibiotic prophylaxis for dental treatment.

Smoking was not an exclusion criterion.

Each subject received a clinical examination by one of two calibrated examiners consisting of full-mouth recording of probing depths (PDs) and

clinical attachment levels (CALs) at six sites per tooth for all fully erupted teeth, except third molars

using a University of North Carolina 15 probe with measures rounded up to the nearest millimeter(8).

Alveolar bone levels (BLs) were measured as previously described from a full mouth series of periapical radiographs taken for each subject using the long-cone paralleling technique(10).

All radiographs were exposed with settings at 70 kilovolt (peak) and 15 mA. Films were processed under standardized conditions using an automatic processor. Radiographic analysis was performed by projecting each x-ray film onto a solid white surface at a fixed distance, providing a magnification of ×3.5.

All measurements were made in a darkened room with a clear plastic millimeter rule.

BL was determined by measurement of the distance from the cementoenamel junction (CEJ) to the alveolar crest and was made by aligning the ruler along the outer surface of the root of the tooth and measuring the distance from the CEJ to the most coronal extent of the periodontal ligament, as previously described(10).

In situations in which the CEJ or alveolar crest could not be clearly identified, the interproximal surface was recorded as being non-measurable.

Only proximal surfaces were used in the analysis, and for each evaluated radiographic surface, mean values of the buccal and lingual proximal clinical measures for PD and CAL were used for comparison with BL at that surface. Clinical BW is defined as the distance from the most coronal level of the CAL to the BL.

Because the CEJ is used to calculate CAL and BL, clinical BW was calculated as BL - CAL and was considered to consist of the supra-crestal connective tissue fibers and the junctional epithelium as previously described(2).

STATISTICAL ANALYSES

Descriptive statistical analyses for the mean – SD with 95% confidence intervals about the mean were performed.

The intercorrelations among PD, CAL, BL, and BW were compared for all sites as well as for sites grouped by PD ranges of <2, 2 to 4, 5 to 7, and >7mm and CAL ranges of 0 to 2, 3 to 6, and >6 mm.

A comparison was made, using a one-sample multivariate analysis of variance, of the data obtained from this study for the clinical BW in subjects with severe, generalized, chronic periodontitis and the means previously obtained for the histologic BW(2).

RESULTS

The clinical analysis of this population with severe, generalized, chronic periodontitis revealed that 44% of all measured sites had PD and CAL ≤3 mm.

These clinical observations suggested that even in the presence of a severe, generalized, horizontal pattern of alveolar bone loss, nearly half of the clinical sites in the mouth showed minimal clinical signs of disease but extensive radiographic evidence of alveolar bone loss.

When we examined the relationship between PD and the calculated clinical BW (Table 1), statistically significant increases in the clinical BW were observed compared to the mean values previously reported for the histologic BW(2).

At sites with PD <2 mm, there was a mean BW of 5.02 mm across all subjects, with a median of 4.90mm(Table 1). Consistent with previously reported histologic measures of BW, the range of measurements for all sites with PD <2mm was considerable, ranging from 1.6 mm to as much as 9 mm

As PD increased, the associated mean BW tended to decrease.

However, for all levels of PD, the clinical BW was significantly greater than that previously reported for the histologic BW.

Similar findings were observed when the evaluation of BW was based on CAL at an individual site (Table 2).

Sites with CAL of 0 to 2mm had an average BW of 5.35mm, with a median of 5.16mm and a range of 3.00 to 9.35 mm.

Consistent with the observations based on PD (Table 1), the average BW tended to decrease with increasing CAL, but it was always statistically significantly greater than previously reported for the histologic BW in subjects without significant periodontal pathology(2).

An analysis of the intercorrelation coefficients and their statistical significance was performed for PDs of 2 to 4, 5 to 7, and >7 mm and for all PDs combined (Table 3).

Comparisons were made between PD and BL, PD and BW, BL and BW for each range of PD.

For all sites combined, PD was significantly correlated with BL (P <0.001).

However, PD was not significantly correlated with BL at the individual ranges of PD nor was it significantly correlated with BW, confirming our initial observation of a disassociation between PD and BW in subjects with severe, generalized periodontitis.

BL was significantly correlated wit BW for each group of PDs and for all sites combined as would be expected, because bone levels are used in the determination of the BW.

Similar correlations were found when sites were examined by CAL (Table 4).

Significant correlations were found between CAL and BL but only for moderate to severe attachment loss.

However, no correlation was observed between CAL and BW at any range of CAL or for all sites combined.

BL was significantly correlated with BW at all sites because BL is used in the calculation of BW.

DISCUSSION

BW is an important clinical concept in restorative dentistry and periodontics(4,11).

Although the frequently used histologic measure for BW, 2.04 mm, is the reported average from many measurements, it has not been generally understood that considerable variability exists in the dimensions of the dentogingival junction that constitute the BW(2,4).

In the original study(2) that is frequently referenced for BW, 325 measures were taken on 287 teeth in 30 autopsy jaws. Although the investigators stated that ‘‘all specimens were free of extensive pathology and fulfilled the requirements of clinically normal specimens,’’ they had been classified by their various stages of ‘‘passive eruption,’’ a term used to characterize the exposure of the anatomic crown because of gingival recession.12

The phases of passive eruption are based on the location of the dentoepithelial junction (DEJ).

In phase I, the DEJ is located on enamel and, therefore, is consistent with periodontal health or gingivitis, depending on the presence or absence of inflammation.

In phase II, the DEJ is located on enamel and cementum and, therefore, depicts early stages of periodontitis.

In phase III, the DEJ is located entirely on cementum;

In phase IV, the DEJ is on cementum, and the root surface is exposed.

Phases III and IV would be termed periodontitis because loss of attachment had occurred.

The most consistent reported component of the histologic BW was the width of the supracrestal connective tissue, which averaged

1.08 mm in phase I (range: 0.75 to1.49mm), 1.07mm in phase II (range: 0.81 to 1.56mm), 1.06mmin phase III (range: 0.69 to 1.53 mm), 1.06mmin phase IV (range: 0.89 to 3.10 mm)2,4.

Greater variability was seen in the length of the junctional epithelium, averaging

1.35mmin phase I (range: 1.14 to 1.56 mm), 1.10 mmin phase II (range: 0.80 to 1.35 mm), 0.74 mmin phase III (range: 0.44 to 0.88 mm), 0.71 mm in phase IV (range: 0.53 to 0.88 mm).2,4

There are no comprehensive evaluations of BW in more advanced cases of periodontitis where significant changes in connective tissue and bone have occurred.

The present study took advantage of baseline data obtained as part of an intervention study in subjects with severe, generalized, chronic periodontitis to examine the changes in BW that might occur in periodontitis(8 ).

The first observation was that the average clinical BW in cases of severe, generalized, chronic periodontitis was nearly twice as large as previously reported for the histologic BW in cases of health to mild periodontitis (3.95 mm versus 2.04 mm).

What was even more surprising was the extreme range of values obtained for BW, based on initial PD or CAL, with values<1to>9mm.

An examination of inter-correlation coefficients confirmed our initial observation (Fig. 2) that sites with the shallowest PDs and least CAL had the greatest BW.

This observation provides significant implications for the selection of surgical or non-surgical approaches in the treatment of patients with severe periodontitis.

It was demonstrated that surgical intervention in sites with shallow PDs resulted in post-surgical loss of attachment at that site(13-18).

In cases of severe, generalized, chronic periodontitis in which the BW at shallow sites may be at least twice as much as first described, with extremes of up to 9mm,there is considerable potential for extensive attachment loss as the result of open flap debridement with scaling and root planing or with apically positioned flaps.

REFERENCES

1. Stanley HR Jr. The cyclic phenomenon of periodontitis. Oral Surg Oral Med Oral Pathol 1955;8:598-610.

2. Gargiulo AW, Wentz FM, Orban B. Dimensions and relations of the dento-gingival junction in humans. J Periodontol 1961;32:261-267.

3. Ingber JS, Rose LF, Coslet JG. The ‘‘biologic’’ width –A concept in periodontics and restorative dentistry. Alpha Omegan 1977;70:62-65.

4. Gargiulo A, Krajewski J, Gargiulo M. Defining biologic width in crown lengthening. CDS Rev 1995;88:20-23.

5. Page RC, Kornman KS. The pathogenesis of human periodontitis: An introduction. Periodontol 2000 1997; 14:9-11.

6. Waerhaug J. The gingival pocket. Odontol Tidskr 1952; 60:95-134.7. Novak MJ, Polson AM, Caton J, Freeman E, Meitner S. A periodontal attachment

mechanism without alveolar bone. Case report. J Periodontol 1983;54:112-118.8. Novak MJ, Johns LP, Miller RC, Bradshaw MH. Adjunctive benefits of

subantimicrobial dos doxycycline in the management of severe, generalized, chronic periodontitis. J Periodontol 2002;73:762-769.

9. Armitage GC. Development of a classification system for periodontal diseases and conditions. Ann Periodontol 1999;4:1-6.

10. Reed BE, Polson AM. Relationships between bitewing and periapical radiographs in assessing crestal alveolar bone levels. J Periodontol 1984;55:22-27.

11. Hildebrand CN. Crown lengthening for optimum restorative success. Compendium 2003;24:620-629.

12. Orban B, Kohler J. The physiologic gingival sulcus. Ztschr Stomatol 1924;22:353-425.13. Knowles JW, Burgett FG, Nissle RR, Shick RA, Morrison EC, Ramfjord SP. Results of periodontal

treatment related to pocket depth and attachment level. Eight years. J Periodontol 1979;50:225-233.

14. Lindhe J, Westfelt E, Nyman S, Socransky SS, Heijl L, Bratthall G. Healing following surgical/non-surgical treatment of periodontal disease. A clinical study. J Clin Periodontol 1982;9:115-128.

15. Lindhe J, Westfelt E, Nyman S, Socransky SS, Haffajee AD. Long-term effect of surgical/non-surgical treatment of periodontal disease. J Clin Periodontol 1984;11:448-458.

16. Pihlstrom BL, McHugh RB, Oliphant TH, Ortiz-Campos C. Comparison of surgical and nonsurgical treatment of periodontal disease. A review of current studies and additional results after 6 1/2 years. J Clin Periodontol1983;10:524-541.

17. Pihlstrom BL, Oliphant TH, McHugh RB. Molar and nonmolar teeth compared over 6 1/2 years following two methods of periodontal therapy. J Periodontol 1984;55:499-504.

18. Ramfjord SP, Caffesse RG, Morrison EC, et al. 4 modalities of periodontal treatment compared over 5 years. J Clin Periodontol 1987;14:445-452.

Thank you

BIOLOGIC WIDTH

The term biologic width is familiar to most clinicians, yet there still exists confusion regarding its meaning and relevance to clinical procedures.

The biologic width is defined as the dimension of the soft tissue, which is attached to the portion of the tooth coronal to the crest of the alveolar bone.

This term was based on the work of Gargiulo et al. (1961), who described the dimensions and relationship of the dentogingival junction in humans.

Measurements made from the dentogingival components of 287 individual teeth from 30 autopsy specimens established that there is a definite proportional relationship between the alveolar crest, the connective tissue attachment, the epithelial attachment, and the sulcus depth

Gargiulo et al. (1961) reported the following mean dimensions: a sulcus depth of 0.69mm, an epithelial attachment of 0.97mm, and a connective tissue attachment of 1.07mm. Based on this work, the biologic width is commonly stated to be 2.04mm, which represents the sum of the epithelial and connective tissue measurements.

One must realize however that significant variations of dimensions were observed, particularly the epithelial attachment, which ranged from 1.0 to 9.0mm. The connective tissue attachment, on the other hand, was relatively constant.

Recently, similar biologic width dimensions were also reported (Vacek et al. 1994). Evaluating 171 cadaver tooth surfaces, they observed mean measurements of 1.34mm for sulcus depth, 1.14 for epithelial attachment, and 0.77mm for connective tissue attachment. This group also found that the connective tissue attachment was the most consistent measurement

There is general agreement that placing restorative margins within the biologic width frequently leads to gingival inflammation, clinical attachment loss, and bone loss. This is thought to be due to the destructive inflammatory response to microbial plaque located at deeply placed restorative margins. Clinically, these changes are manifested as deepened periodontal pockets or gingival recession. These changes have been substantiated by studies that have assessed the histological and clinical responses of periodontal tissues to restorative margins placed within the biologic width. Newcomb (1974) analyzed 66 anterior crowns with subgingival margins of varying depths and compared them to uncrowned contralateral controls. The results showed that the nearer a subgingival crown margin was to the epithelial attachment (hence nearer the biologic width), the more likely that severe gingival inflammation occurred.

Parma-Benfenati et al. (1986) observed approximately 5mm of osseous resorption when restorative margins were placed at the alveolar crest in beagle dogs. Minimal resorption was observed where restorations were placed 4 mm coronal to the alveolar crest. Bone resorption was particularly severe in areas with thin cortical bone

Recently, Gunay et al.(2000) demonstrated that restorative margin placement within the biologic width was detrimental to periodontal health. In a 2-year study, they evaluated 116 prepared teeth compared to 82 unrestored teeth in 41 patients. Papillary bleeding score and probing depths increased at sites where the restorative margin was o1mm from the alveolar crest.

Various authors have recommended minimal distances restorative margins must be from the bone crest to avoid deleterious effects. Ingber et al. (1977) suggested that a minimum of 3mm was required from the restorative margin to the alveolar crest to permit adequate healing and restoration of the tooth.

Maynard & Wilson (1979) divided the periodontium into three dimensions: superficial physiologic- The superficial physiologic dimension represents the free

and attached gingiva surrounding the tooth crevicular physiologic - while the crevicular physiologic dimension represents

the gingival crevice – extending from the free gingival margin to the junctional epithelium

Subcrevicular physiologic- The subcrevicular physiologic space is analogous to the biologic width described by Gargiulo et al. (1961), consisting of the junctional epithelium and connective tissue attachment.

Maynard & Wilson claimed that all three of these dimensions affect restorative treatment decisions and the clinician should ‘conceptualize’ all three areas and the interplay between them and restorative margins.

certain conditions necessitate placement of subgingival margins. These may include esthetic concerns, need for increased retention form, refinement of preexisting margins, root caries, cervical abrasion, and root sensitivity. However, if none of these factors is of concern, it appears prudent to place restorative margins supragingivally.

In 1961, Gargiulo et al1 published their now classic data on attachment measurements. They reported the mean measurement of epithelial attachment plus connective tissue attachment was 2.04 mm.

In 1977, Ingber et al2 described “Biologic Width” and credited D.Walter Cohen for first coining the term.

1990s, Kois published his classic papers on biologic width.3,4 He proposed three categories of biologic width based on the total dimension of attachment plus the sulcus depth

In order to operationally define biologic width, Kois suggested that the restorative dentist must

determine the total distance from the gingival crest to the alveolar crest. This procedure is termed bone sounding. The patient is anesthetized and the periodontal probe is placed in the sulcus and pushed through the attachment apparatus until the tip of the probe engages alveolar bone (Figure 8). Based on this measurement, the three categories of biologic width he described are Normal Crest (Figure 9), High Crest (Figure 10), and Low Crest