Determination of clinical biologic width in chronic generalized periodontitis and healthy periodontium: A clinico-radiographical study.

BACKGROUND: The dimensions of dentogingival junction have been evaluated from autopsy jaw specimens. Previous studies demonstrated variability in histologic biologic width (BW) in periodontal health and mild periodontitis. Few studies have been done on the measurement of clinical BW in periodontitis. BW variation provides implications for selection of surgical or nonsurgical approaches. The purpose of this study was to determine clinical BW in periodontal health and chronic generalized periodontitis and to compare it with histologic dimensions of BW.
MATERIALS AND METHODS: A total of 20 subjects with chronic generalized periodontitis and 20 subjects with healthy periodontium were included in the present study. Plaque index and community periodontal index of treatment needs were scored; moreover, probing depth (PD) and clinical attachment level were measured. Full mouth intraoral periapical radiographs were taken, and digitalized images were obtained to measure the crestal bone level using computerized software.
RESULTS: Clinical BW was significantly greater in both healthy and periodontitis groups than previously reported histologic BW of 2.04 mm (P < 0.001). The mean clinical BW was 3.98 mm.
CONCLUSION: Mean clinical BW in both groups was significantly greater than histologic BW and sites with shallow PDs demonstrated greatest BW, suggesting that these sites may be at increased risk for losing significant attachment during surgical procedures.

INTRODUCTION

The dentogingival junction to the tooth surface is composed of a fibrous, supracrestal connective tissue attachment and an epithelial attachment (junctional epithelium), and its dimensions have been delineated from autopsy jaw specimens by Gargiulo et al.[1] The supracrestal 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.[2]

The histologic dimensions of the BW were comprehensively evaluated on teeth from autopsy specimens of subjects 19-50 years of age and the results showed an average width of 1.07 mm for connective tissue and 0.97 mm for the junctional epithelium and these dimensions varied considerably with age and level of apical migration of the epithelial attachment.[1]

According to Gargiulo et al. in 1985,[3] the mean values obtained from these studies do not truly reflect the variability that exists in the dimensions of the dentogingival junction. 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.[3]

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.[4]

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 1.94-1.97 mm. Although significant variations can occur in BW, especially in the length of the epithelial attachment, an average value of 2.04 mm is considered to be the norm in most of the teeth in most of the patients.[13]

The supracrestal 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.[5] Studies of young adults with severe generalized periodontitis have shown 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. But considerable variability has been shown to exist in the dimensions of the BW in cross-sectional studies[16] of autopsy materials with no overt periodontal pathology. Very few studies,[7] have been done on the measurement of BW in humans with clinically diagnosed periodontitis. Hence, the purpose of this study was to determine clinical BW in healthy subjects and patients with chronic generalized periodontitis and to compare it with previously established histologic dimensions of BW.

MATERIALS AND METHODS

The present study was conducted on 20 patients with chronic generalized periodontitis and 20 subjects with healthy periodontium visiting department of Periodontics, H.K.E. Society's S. Nijalingappa Institute of Dental Sciences and Research, Gulbarga, Karnataka, India, between 2010 and 2011. The study design was explained to the patients, and informed consents were obtained. The project was approved by the ethical committee at H.K.E. Society's S. Nijalingappa Institute of Dental Sciences and Research.

The inclusion criteria were subjects between the age group of 30-60 years. Subjects having ≥20 teeth with ≥30% of measured sites with ≤4 mm of probing depth (PD) and ≤2 mm clinical attachment level (CAL) were considered healthy. Subjects having ≥20 teeth with ≥30% of measured sites with ≥5 mm of PD and ≥3 mm clinical attachment loss were considered chronic generalized periodontitis. Subjects were excluded from participating in the study if they had received antibiotic therapy 3 months prior to study or nonsurgical periodontal therapy 3 months prior to study or received surgical periodontal therapy 12 months prior to study. Pregnant and lactating females and subjects with systemic diseases and conditions and subjects with crowns or fixed partial dentures were excluded from the study.

Each subject received a clinical examination by a calibrated examiner consisting of full-mouth recording of PDs and 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. Full-mouth series of periapical radiographs were taken for each subject using the long-cone paralleling technique. All radiographs were exposed with settings at 70 kilovolt and 8 mA. The radiographs were scanned to obtain digitalized images to measure the crestal bone level (CBL - that is the distance from cementoenamel junction (CEJ) to the alveolar crest) on proximal surfaces using computerized software [Figure 1]. Clinical BW is defined as the distance from the most coronal level of the CAL to the CBL. As CEJ is used to calculate CAL and CBL, clinical BW was calculated by subtracting the CAL from CBL.

Figure 1

Measuring crestal bone level using computerized software

Statistical analysis

Results are expressed as mean ± standard deviation (SD) and range values. Pearson's correlation coefficient was used to measure the degree of relationship between different parameters. Intergroup comparisons were done using t-test for independent samples. A P value of 0.05 or less was considered for statistical significance. The statistical analysis was conducted by the mean of SPSS Version 16 (Chicago, IL, USA) package.

RESULTS

The demographic data of the study population is shown in Table 1. Each group consisted of 20 patients. The healthy group consisted of 10 males and 10 females with a mean age of 38.5 ± 7.7 and range of 30-50 years. The chronic generalized periodontitis group consisted of 9 males and 11 females with a mean age of 41.7 ± 8.0 and a range of 30-56 years [Table 1].

Table 1

Demographic data of the study groups

The relationship of PD with clinical BW in a healthy group is shown in Table 2. The PD measurements were divided into two groups, <2 mm, 2-4 mm. At sites with PD <2 mm, mean BW was 4.87 ± 0.63 mm with a median of 5.1 mm (range: 3.6-5.5). For PD 2-4 mm, mean BW was 4.57 ± 0.76 mm with a median of 4.8 mm (range: 3-6.3). As PD increased, the associated mean BW tended to decrease. However, the clinical BW was significantly greater than that previously reported for the histologic BW [Figure 2].

Table 2

Relationship of PD with clinical BW in a healthy group

Figure 2

Relationship of probing depth with clinical biologic width

Table 3 shows the relationship of PD with clinical BW in the periodontitis group. The PD measurements were divided into two groups 5-7 mm and ≥7 mm. At sites with PD 5-7 mm, mean BW was 3.64 ± 0.49 mm with a median of 3.6 mm (range: 2.1-5.3). For sites with PD ≥7 mm, mean BW was 3.40 ± 0.48 mm with a median of 3.3 mm (range: 2.6-5.3) and at all sites, mean BW was 3.98 ± 0.78 mm with a median of 3.7 mm (range: 2.1-6.3). 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 [Figure 2].

Table 3

Relationship of PD with clinical BW in the periodontitis group

The relationship of CAL with clinical BW in a healthy group is shown in Table 4. Mean BW was 5.08 ± 0.39 mm, with a median of 5.1 mm (range: 3.1-6.3). As CAL increased, the associated mean BW tended to decrease. However, the clinical BW was significantly greater than that previously reported for the histologic BW [Figure 3].

Table 4

Relationship of CAL with clinical BW

Figure 3

Relationship of clinical attachment level with clinical biologic width

Table 5 shows relationship of CAL with clinical BW in the periodontitis group. The CAL measurements were divided into two groups: 3-6 mm and ≥6 mm. For CAL 3-6 mm, mean BW was 3.68 ± 0.48 mm with a median of 3.6 mm (range: 2.1-5.6). At sites with CAL ≥6 mm, mean BW was 3.44 ± 0.50 mm with a median of 3.3 mm (range: 2.6-5.3) and at all sites, mean BW was 3.98 ± 0.78 mm with a median of 3.7 mm (range: 2.1-6.3). As CAL increased, the associated mean BW tended to decrease. However, for all levels of CAL, the clinical BW was significantly greater than that previously reported for the histologic BW [Figure 3].

Table 5

Relationship of CAL with clinical BW

An intercorrelation coefficients using Pearson's correlation coefficient, and their statistical significance was performed for PDs of 2-4, 5-7 and ≥7 mm and for all PDs combined [Table 6]. Comparisons were made between PD and CBL, PD and BW, and CBL and BW for each range of PD. The r values obtained from correlation between PD and CBL for individual ranges of PD that is, for 2-4 mm, 5-7 mm, ≥7 mm and all sites combined were 0.17, 0.53, 0.58, and 0.67, respectively, and PD was significantly correlated with CBL with P = 0.001. The r values obtained from correlation between PD and CBL for individual ranges of PD that is, for 2-4 mm, 5-7 mm, ≥7 mm and all sites combined were-0.31,-0.18,-0.12,-0.62, respectively, indicating an inverse relationship between PD and BW, that is, as PD increased BW decreased. This finding was significant for individual ranges and all sites combined with P = 0.001 except for PD ≥ 7 mm. The r values obtained from correlation between PD and CBL for individual ranges of PD that is, for 2-4 mm, 5-7 mm, ≥7 mm and all sites combined were − 0.35, 0.13, 0.31, and − 0.39, respectively. CBL was significantly correlated with BW for each group of PDs and for all sites combined.

Table 6

Intercorrelation coefficients made between PD and CBL, PD and BW and CBL and BW for each range of PD

An intercorrelation coefficients using Pearson's correlation coefficient and their statistical significance was performed for CAL of 0-2, 3-6 and ≥6 mm and for all CAL combined [Table 7]. Comparisons were made between CAL and CBL, CAL and BW, and CBL and BW for each range of CAL. The r values obtained from correlation between CAL and CBL for individual ranges of CAL i.e. 0-2 mm, 3-6 mm, ≥6 mm and all sites combined were 0.81, 0.47, 0.89, and 0.91, respectively. CAL was significantly correlated with CBL with P value 0.001. The r values obtained from correlation between CAL and CBL for individual ranges of CAL that is, 0-2 mm, 3-6 mm, ≥6 mm and all sites combined were − 0.32, −0.43, −0.04 and − 0.74 respectively. An inverse relationship was seen between CAL and BW, that is, as CAL increased BW decreased. This finding was significant for individual ranges and for all sites combined with P = 0.001 except for PD ≥ 6 mm which was not significant with P = 0.64. The r values obtained from correlation between CAL and CBL for individual ranges of CAL that is, 0-2 mm, 3-6 mm, ≥6 mm and all sites combined were 0.31, 0.21, 0.43, and − 0.39, respectively. CBL was significantly correlated with BW for each group of PDs and for all sites combined with P = 0.001, as would be expected, because bone levels are used in the determination of the BW.

Table 7

Intercorrelation coefficients made between CAL and CBL, CAL and BW, and CBL and BW for each range of CAL

DISCUSSION

A great part of periodontal literature deals with the checking, reconstruction, and maintenance of BW. Gargiulo et al.[1] reported in 1961 a certain uniformity of the dimension of some components of BW:

Mean depth of the histologic sulcus is 0.69 mm

Mean junctional epithelium measures 0.97 mm (0.71-1.35 mm)

Mean supraalveolar connective tissue attachment is 1.07 mm (1.06-1.08 mm).

The total of the attachment is, therefore, 2.04 mm (1.77-2.43 mm) and is called the BW and is essential for preservation of periodontal health and removal of irritation that might damage the periodontium (prosthetic restorations, for example). The millimeter that is needed from the bottom of the junctional epithelium to the tip of the alveolar bone is held responsible for the lack of inflammation and bone resorption and as such a development of periodontitis. The dimension of BW is not constant, it depends on the location of the tooth in the alveola, varies from tooth to tooth, and also from the aspect of the tooth. Its constancy can only be found in healthy dentition.

BW is an important clinical concept in restorative dentistry and periodontics.[34] 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.[13] There are no comprehensive evaluations of BW in more advanced cases of periodontitis where significant changes in connective tissue and bone has occurred. Hence, the aim of this study was to determine clinical BW in healthy subjects and patients with chronic generalized periodontitis and to compare it with previously established histologic dimensions of BW.

In the original study,[1] 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.[8] The phases of passive eruption are based on the location of the dento-epithelial junction (DEJ). In the phase I, the DEJ is located on the enamel and, therefore, is consistent with periodontal health or gingivitis, depending on the presence or absence of inflammation. Inphase 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 the 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 mminphase I (range: 0.75 to1.49 mm), 1.07 mm in phase II (range: 0.81-1.56 mm), 1.06 mm in phase III (range: 0.69-1.53 mm), and 1.06 mm in phase IV (range: 0.89-3.10 mm).[13] Greater variability was seen in the length of the junctional epithelium, averaging 1.35 mmin phase I (range: 1.14-1.56 mm), 1.10 mm in phase II (range: 0.80-1.35 mm), 0.74 mm in phase III (range: 0.44-0.88 mm), and 0.71 mm in phase IV (range: 0.53-0.88 mm).[13]

Other studies,[910] which have histologically determined the BW in adult human cadaver jaws obtained mean measurements of 1.14 ± 0.49 mm for epithelial attachment, 0.77 ± 0.32 mm for connective tissue attachment, 2.17 mm for BW, 1.07 mm for junctional epithelium, and 1.10 mm for the connective tissue. There are no comprehensive evaluations of BW in more advanced cases of periodontitis where significant changes in connective tissue and bone have occurred.

In the present study, the first observation was that the average clinical BW in cases of chronic generalized periodontitis was 3.95 mm, which was twice the histologic BW in cases of health to mild periodontitis, as reported in previous studies. Based on initial PD and CAL, extreme range of values of <1 to >9 mm for BW were obtained, and these findings were similar to the study done by Novak et al.[7]

An examination of intercorrelation coefficients confirmed our initial observation that sites with the shallowest PDs and least CAL had the greatest BW. This observation provides significant implications for the selection of surgical or nonsurgical approaches in the treatment of patients with severe periodontitis. It was demonstrated that surgical intervention in sites with shallow PDs resulted in postsurgical loss of attachment at that site.[1112131415]

CONCLUSIONS

The mean clinical BW in subjects with healthy periodontium and subjects with chronic generalized periodontitis seemed to be significantly greater than the histologic BW previously reported for subjects not demonstrating significant periodontal pathology. In addition, sites with shallow PDs demonstrated the greatest BW, suggesting that these sites may be at increased risk for losing clinically significant attachment during surgical procedures.