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Table of Contents   
ORIGINAL RESEARCH  
Year : 2011  |  Volume : 22  |  Issue : 2  |  Page : 237-241
Evaluation of an innovative radiographic technique - parallel profile radiography - to determine the dimensions of dentogingival unit


1 Department of Periodontics, VS Dental College and Hospital, Bangalore, Karnataka, India
2 Department of Periodontics, Jodhpur Dental College General Hospital, Jodhpur, India

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Date of Submission07-Feb-2010
Date of Decision21-Apr-2010
Date of Acceptance28-Sep-2010
Date of Web Publication27-Aug-2011
 

   Abstract 

Background: Maintenance of gingival health is a key factor for longevity of the teeth as well as of restorations. The physiologic dentogingival unit (DGU), which is composed of the epithelial and connective tissue attachments of the gingiva, functions as a barrier against microbial entry into the periodontium. Invasion of this space triggers inflammation and causes periodontal destruction. Despite the clinical relevance of the determination of the length and width of the DGU, there is no standardized technique. The length of the DGU can be either determined by histologic preparations or by transgingival probing. Although width can also be assessed by transgingival probing or with an ultrasound device, they are either invasive
or expensive
Aims: This study sought to evaluate an innovative radiographic exploration technique - parallel profile radiography - for measuring the dimensions of the DGU on the labial surfaces of anterior teeth.
Materials and Methods: Two radiographs were made using the long-cone parallel technique in ten individuals, one in frontal projection, while the second radiograph was a parallel profile radiograph obtained from a lateral position. The length and width of the DGU was measured using computer software. Transgingival probing (trans-sulcular) was done for these same patients and length of the DGU was measured. The values obtained by the two methods were compared. Pearson product correlation coefficient was calculated to examine the agreement between the values obtained by PPRx and transgingival probing.
Results: The mean biologic width by the parallel profile radiography (PPRx) technique was 1.72 mm (range 0.94-2.11 mm), while the mean thickness of the gingiva was 1.38 mm (range 0.92-1.77 mm). The mean biologic width by trans-gingival probing was 1.6 mm (range 0.8-2.2mm). Pearson product correlation coefficient (r) for the above values was 0.914; thus, a high degree of agreement exists between the PPRx and TGP techniques.
Conclusions: We conclude that the biologic width of the DGU in humans can be measured with the PPRx technique. The values obtained agree with the values obtained by transgingival probing, a technique considered standard so far. Thus, the PPRx technique offers a simple, concise, noninvasive, and reproducible method that can be used in the clinical setup to measure both the length and thickness of the DGU with accuracy.

Keywords: Dentogingival unit, gingival thickness, transgingival probing, radiographs

How to cite this article:
Galgali SR, Gontiya G. Evaluation of an innovative radiographic technique - parallel profile radiography - to determine the dimensions of dentogingival unit. Indian J Dent Res 2011;22:237-41

How to cite this URL:
Galgali SR, Gontiya G. Evaluation of an innovative radiographic technique - parallel profile radiography - to determine the dimensions of dentogingival unit. Indian J Dent Res [serial online] 2011 [cited 2019 Aug 23];22:237-41. Available from: http://www.ijdr.in/text.asp?2011/22/2/237/84294
The dentogingival junction has been described as a functional unit composed of the connective tissue attachment of the gingiva as well as the epithelial attachment. Gargiulo et al. defined the term physiologic dentogingival unit (DGU) as the anatomic complex formed by the gingival margin, the sulcus, the junctional epithelium, and the connective tissue attachment. They stressed that the epithelial and connective tissue attachments are the main components of this functional unit. [1] Later, the term 'biologic width' was introduced by Cohen to describe the space over the tooth surface that is occupied by the connective tissue and epithelial attachments, this parameter being equivalent to the distance between the bottom of the gingival sulcus and the alveolar bone crest. [2] In humans this distance is 2.04 mm on average [0.97 mm (epithelial attachment) +1.07 mm (connective tissue attachment)].

The DGU is important for gingival health, and encroachment on it may cause breakdown and apical migration of the attachment apparatus. The biological width is considered to be essential for maintaining gingival health, especially in the case of teeth in need of restoration. [3] It is also important to establish an ideal dimension of the DGU during

crown-lengthening procedures. Ingber et al. emphasized the importance of maintenance of biologic width when restoring teeth. They concluded that a space of 3 mm coronal to the alveolar crest is necessary to permit healing and proper restoration of the tooth and that violation of the biologic width would lead to periodontal reactions. [4]

Although the clinical relevance of determining the length and thickness of biological width is obvious, there is no description in the literature of any standardized, noninvasive, simple technique for measurement of the biological width BW in living subjects.

This study was done to evaluate an innovative radiographic technique, i.e., parallel profile radiography (PPRx), for measuring the dimensions of the DGU on the labial surfaces of anterior teeth. We compared the values obtained with this technique with that by the transgingival probing technique.


   Materials and Methods Top


Ten volunteers were enrolled in the study from among the patients reporting to the Department of Periodontics, VS Dental College and Hospital, Bangalore. This study was approved by the institutional review board. The purpose of the study and the type of exploration were clearly explained and written consent was obtained from all participants. The inclusion criteria were as follows: age between 20-40 years, absence of restorations in the area between the maxillary canines, absence of periodontal pathology, absence of systemic pathology that could have repercussions on the periodontium, and absence of previous orthodontic movement.

To study the dimensions of the soft and hard structures of the most coronal area of the periodontium, one of the two central incisors was selected. In each individual, two radiographs were made using the long-cone parallel technique. The first radiograph was made in the frontal projection in a standard manner; the second was a parallel profile radiograph that was obtained from a lateral view.

To highlight the soft tissue structures on the radiograph, the auxiliary elements used were gutta percha and lead foil because of their opaque nature. The most apical point of the gingival sulcus was assessed by probing [Figure 1]. After probing, gutta percha was cut to the sulcus depth [Figure 2], inserted up to the base of the sulcus, and aligned with the long axis of the tooth; its coronal end remained visible slightly above the gingival margin [Figure 3]. The lead foil was cut appropriately [Figure 4] and then positioned over the gingival surface, aligned with the long axis of the tooth. This would serve to delimit the profile of the gingiva from the lateral perspective. The XCP paralleling system (Dentsply) was then used. The first radiograph was taken in the frontal projection. The paralleling device was placed in such a way that the film was positioned on the lateral vestibule When the patient fixes teeth on the bite block [Figure 5].
Figure 1: Assessment of sulcus depth

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Figure 2: Gutta-percha cut appropriately

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Figure 3: Gutta-percha aligned into the sulcus

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Figure 4: Lead foil cut appropriately

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Figure 5: Paralleling device in position

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The radiographs thus obtained were digitized using a scanner. The images were imported to Adobe Photoshop CS2. This software allows the operator to draw straight lines between two points, and the program measures the distance between those points with a precision of 0.1 mm [Figure 6]a and b. The following measurements were made:
Figure 6: (a,b)Parallel profile radiograph obtained and adobe photoshop applied

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  • Distance between the bottom of the gingival sulcus (apical end of gutta percha) and the bone crest - thus, the length of the DGU
  • Thickness of labial soft tissue measured from the palatal face of the lead plate to the root surface - thus, the width of the DGU


Transgingival probing was done for the same patients according to the method described by Laster and Listgarten. [5] Measurements were carried out with a calibrated UNC-15 (In-Sci® )-type of periodontal probe. Each probe was fitted tightly with a silicon rubber sliding 'stop.' Under local anesthesia the probe was placed in the corono-apical direction, held against the tooth, and advanced apically so that the rubber stop would stay at the incisal edge with the probe tip at the base of sulcus [Figure 7]. This distance was assessed with Vernier calipers [Figure 8]. The probe was then advanced further apically until osseous tissue was felt and this distance was also recorded. The difference of the two recorded measurements indicated the distance (in millimeters) from the base of the sulcus to the alveolar crest, i.e., the biological width. [2] However, transgingival probing could not be used to assess the thickness of the gingiva as it was difficult to select and standardize the site of assessment.
Figure 7: Transgingival probing with rubber stop

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Figure 8: Biologic width measured with vernier caliper

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   Results Top


The mean length of biologic width by the PPRx technique was 1.72 mm (range 0.94-2.11 mm) [Table 1], while the mean thickness of the gingiva was 1.38 mm (range 0.92-1.77 mm) [Table 2]. The length of biologic width, as measured by transgingival probing, was 1.6 mm (range 0.8-2.2 mm) [Table 1]. Pearson product correlation coefficient was calculated to assess the correlation between the values obtained by the two methods; the r value was 0.914, showing that there is a high degree of agreement between the PPRx and transgingival probing techniques.
Table 1: Dimensions of DGU obtained by PPRx technique and transgingival probing


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Table 2: Thickness of gingival obtained by PPRx technique


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   Discussion Top


In 1961, Gargulio et al. in their classical study established the dimensions of the DGU in 30 human jaws obtained from autopsies. The age range of their subjects was 19-50 years. In all, 287 teeth were measured during the four phases of eruption and the authors reported that the mean dimension of biologic width was 2.04mm. The most constant part of the DGU was the connective tissue attachment and the most variable part was the epithelial attachment. [1] In 1994, Vacek et al. studied the dimensions of the DGU on 10 human cadavers with age ranging from 54-78 years and reported that the mean biologic width was 1.91 mm [6] and that the connective tissue attachment had variable width.

Rasheed et al. did a study to find the average biological width in the teeth of 50 Saudi patients with age ranging from 20-50 years. [7] Clinical biological width was calculated by subtracting probing depth from the distance between the gingival margin and the crest of bone. The average biological width in this study was 1.24 mm, with the highest value (1.4 mm) being seen at the mesiobuccal area.

The transgingival (trans-sulcular) probing technique is an old one that has been used often in periodontal practice and research. Its reliability is reported to be very good. Isidor et al. in 1984 reported that measurements obtained with transgingival probing were identical to surgical measurements 60% of the time and were within 1 mm of surgical measurements 90% of the time. [8] Ursell et al. in 1989 reported a mean difference of 0.12 mm between the values obtained by transgingival probing and that by surgical measurement. [9]

The thickness of the connective tissue attachment was measured by Francisco et al. in 2004 by a similar radiographic technique, and they found that it ranges between 1.3-2.4 mm. [10] In the present study, the mean biologic width and the thickness of gingiva was 1.72 mm and 1.48 mm, respectively; this is in accordance with the previously done studies.

Therefore, it is clear that the PPRx technique affords sufficient precision in the determination of the dimensions of the DGU. It is a noninvasive and inexpensive technique that can be used to reliably measure the length and width of the DGU. With this method, the width of DGU can be assessed with accuracy throughout its extent unlike with the transgingival probing technique, which measures the length but not the width. The information regarding dimensions of DGU can be used in research related to intrasulcular restorative margins. PPRx can be useful before crown-lengthening procedures to precisely locate and study the bone crest morphology and its location with respect to the cemento-enamel junction (CEJ), and to evaluate the need for osteoplasty and osteotomy prior to surgery. It can also be used to assess DGU stability and tissue maturity following crown lengthening. This would eliminate any uncertainty as to the waiting period required until definitive prosthesis can be given. [10]

Other dimensions that can be measured by this technique are the free gingival thickness, bone plate thickness, gingival overlap, gingival sulcus depth, and CEJ-bone crest distance (which helps determine the gingival biotype). This is of significance when planning surgical techniques for pocket elimination as well as for predicting the outcome of various mucogingival procedures.

The limitation of this technique is that it cannot be used in posterior teeth and unhealthy periodontal tissues. Since this study was on radiographic images, it was not possible to measure the length of either the junctional epithelium or the connective tissue attachment. [10]

Within the limitations of this study, it can be concluded that the dimensions of human biologic width can be adequately measured with the PPRx technique. The values agree well with that obtained by the transgingival probing technique, which has been considered standard so far. The thickness of gingiva(1.48 mm) measured by the PPRx technique in this study also falls into the range obtained by earlier studies.

This technique can be performed in the office without the need for special equipment and without any patient discomfort. Thus, this study shows the PPRx technique to be a simple, concise, noninvasive, and reproducible technique that can measure both the length and thickness of the DGU with adequate accuracy in the clinical setup.


   Acknowledgments Top


Department of Oral Medicine and Radiology, VS Dental College and Hospital, Bangalore.

 
   References Top

1.Gargiulo AW, Wentz FM, Orban B. Dimensions and relations of the dentogingival junction in humans. J Periodontol 1961;32:12-35.   Back to cited text no. 1
    
2.Cohen DW. Pathogenesis of periodontal disease and its treatment. Washington DC: Walter Reed Army Medical Center; 1962.  Back to cited text no. 2
    
3.Carranza's Clinical Periodontology. In: Spear FM, Cooney JP, Editors. 10th ed. St. Louis, Missouri: Elsevier Publications; 2006:chapter 72, 1052.  Back to cited text no. 3
    
4.Ingber JS, Rose LF, Coslet JG. The 'Biologic width' a concept in periodntics and restorative dentistry. Alpha Omegan 1977;70:62-5.  Back to cited text no. 4
[PUBMED]    
5.Greenberg J, Laster L, Listgarten MA. Transgingival probing as a potential estimator of alveolar bone level. J Periodontol 1976;47:514-7.  Back to cited text no. 5
    
6.Vacek JS, Gher ME, Richardson AC. The dimensions of human dentogingival junction. Int. J Periodont Rest Dent 1994;14:155-65.  Back to cited text no. 6
    
7.Rasheed A, Ghabbon W, Zakour A. Clinical biologic width dimension around dentition of a selected Saudi population. Pak Oral Dent J 2005;25:81-6.  Back to cited text no. 7
    
8.Isidor F, Karring T, Attstrom R. Reproducibility of pocket depth and attachment level measurements using a flexible stent. J Clin Periodontol 1984;11:662-8.  Back to cited text no. 8
    
9.Ursell J. Relationships between alveolar bone levels measured at surgery estimated by transgingival probing and clinical attachment level measurements. J Clin Periodontol 1989;16:81-6.  Back to cited text no. 9
    
10.Alpiste-Illueca F. Dimensions of dentogingival unit in maxillary anterior teeth: a New exploration technique. Int J Periodont Rest Dent 2004;24:386-96.  Back to cited text no. 10
    

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Correspondence Address:
Gauri Gontiya
Department of Periodontics, Jodhpur Dental College General Hospital, Jodhpur
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.84294

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
 
 
    Tables

  [Table 1], [Table 2]

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