|Year : 2016 | Volume
| Issue : 3 | Page : 135-140
An innovative radiographic technique for the determination of dimensions of dentogingival unit in North Indian population
Namdeo Prabhu1, Rakhi Issrani2, Saurabh Mathur2, Gaurav Mishra3
1 Department of Oral and Maxillofacial Surgery, Saraswati Medical and Dental College, Lucknow, Uttar Pradesh, India
2 Department of Oral Medicine and Radiology, Saraswati Medical and Dental College, Lucknow, Uttar Pradesh, India
3 Department of Public Health Dentistry, Saraswati Medical and Dental College, 233, Tiwariganj, Faizabad road, Lucknow, Uttar Pradesh, India
|Date of Web Publication||7-Mar-2017|
Department of Oral Medicine and Radiology, Saraswati Medical and Dental College, Lucknow, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: The physiologic dentogingival unit (DGU), also known as the biologic width, is considered to be essential for longevity of the teeth as well as of restorations. Although the clinical relevance of determining the dimensions of DGU is obvious, there is no description in the literature of any simple, standardized, and noninvasive technique for the measurement of DGU in humans. Aim: This study was undertaken to evaluate an innovative radiographic exploration technique (parallel profile radiography [PPRx]) for measuring the dimensions of the DGU on the labial surfaces of maxillary anterior teeth and to provide additional information on the dimensions of the DGU in humans. Methodology: In this study, two radiographs were made in fifty periodontally healthy volunteers, one in frontal projection, while the second radiograph was a PPRx obtained from a lateral position. The dimensions of the DGU were measured radiographically over these images. All data analyses were performed using SPSS 14.0. Results: PPRx was a highly reproducible exploratory technique. Mean dentogingival measurements on the labial surface of right maxillary central incisor were 1.76 ± 0.87 mm for cementoenamel junction (CEJ)-bone crest distance, 1.39 ± 0.50 for gingival sulcus depth, 1.56 ± 0.28 mm for thickness of connective tissue attachment at CEJ, 1.09 ± 0.28 mm for thickness of free gingiva at its base, 1.95 ± 0.43 mm for biologic width, 0.47 ± 0.22 mm for thickness of bone plate at crest level, and 1.76 ± 0.67 mm for gingival overlap on enamel surface. A statistically significant relationship was observed between gingival width and gingival sulcus depth (P = 0.06). These results suggest that the dimensions of DGU are highly variable in humans. Conclusions: We conclude that the dimensions of the DGU in humans can be measured with the PPRx technique, and this technique offers a simple, concise, noninvasive, inexpensive, and reproducible method that can be used in the clinical setup to measure both the length and thickness of the DGU with accuracy.
Clinical Relevance to Interdisciplinary Dentistry
The dimensions and relationships of the structures of the DGU are essential aspects in many fields of dentistry, and our study strengthen the view that parallel profile radiography can be used as a noninvasive and reliable procedure for measuring the dimensions of the DGU.
Keywords: Dentogingival unit, gingival thickness, radiographs
|How to cite this article:|
Prabhu N, Issrani R, Mathur S, Mishra G. An innovative radiographic technique for the determination of dimensions of dentogingival unit in North Indian population. J Interdiscip Dentistry 2016;6:135-40
|How to cite this URL:|
Prabhu N, Issrani R, Mathur S, Mishra G. An innovative radiographic technique for the determination of dimensions of dentogingival unit in North Indian population. J Interdiscip Dentistry [serial online] 2016 [cited 2019 Dec 10];6:135-40. Available from: http://www.jidonline.com/text.asp?2016/6/3/135/201650
| Introduction|| |
The physiologic dentogingival unit (DGU) junction has been described as the anatomic complex and functional unit formed by the gingival margin, the sulcus, the junctional epithelium, and the connective tissue attachment. Later, the term “biologic width” was introduced 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. 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 for longevity of the teeth as well as of restorations, and its encroachment may cause breakdown and apical migration of the attachment apparatus. Although the clinical relevance of determining the dimensions of the structures of DGU is obvious, the literature makes little reference to this matter, probably because of the inherent difficulties involved. In published literature, majority of the studies have evaluated the dimensions of DGU by conventional histology on cadaver jaws , while few others used different methods such as injection needle or probe, ultrasonic devices,,,, bitewing radiographs, and soft-tissue cone-beam computed tomography. From these studies, it may be concluded that humans exhibit important inter- as well as intra-individual variations in the dimensions of DGU components.
Hence, the present study was aimed to evaluate an innovative radiographic technique, i.e., parallel profile radiography (PPRx), for measuring the dimensions of the DGU without resorting to invasive procedures on the labial surfaces of anterior teeth in North Indian population, and to provide additional information on the dimensions of the DGU in humans.
| Methodology|| |
The research protocol for this study was reviewed and approved by the Institutional Review Board of Saraswati Dental College and Hospital, Lucknow. Fifty periodontally healthy volunteers were enrolled in the study from among the students of Saraswati Dental College and Hospital, Lucknow. The age range was 19–30 years with 18 males and 32 females. The study was done from October to November 2013. The purpose of the study and the type of exploration were clearly explained, and written consent was obtained from all volunteers. The inclusion criteria considered were the presence of all anterior teeth and healthy periodontal tissues, and the exclusion criteria considered were the presence of any systemic pathology with repercussions on the periodontium, use of any medication possibly affecting the periodontal tissues such as cyclosporine A, calcium channel blockers, and phenytoin, pregnancy and lactation, orthodontic or restorative treatment, and smokers.
Labial surface of the right maxillary central incisor was explored clinically with probing of the gingival sulcus and measurement of the gingival bandwidth. The mucogingival line was located by means of the Coppes technique  while the gingival width was determined using a graded periodontal probe, measuring from the mucogingival line to the gingival margin in the medial zone, and expressing the results in millimeters.
To highlight the soft-tissue structures on the radiograph, the auxiliary elements used were gutta-percha and lead foil owing to their opaque nature. The lead foil had fixed dimensions of 5.0 mm × 1.0 mm, and the gutta-percha points used were No. 25. Kodak Ultra Speed No. 2 films developed in an automatic developer were used on all patients.
To study the dimensions of the soft and hard structures of the most coronal area of the periodontium, two radiographs were made using the long-cone parallel technique. The first radiograph was made in the frontal projection in a standard manner ,, while the second was a PPRx that was obtained from a lateral view.
Parallel profile radiography technique
The most apical point of the gingival sulcus of right maxillary central incisor was assessed using a William's standardized probe. After probing, the gutta-percha was cut to the sulcus depth, 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. The lead plate was then positioned over the gingival surface, aligned with the long axis of the tooth [Figure 1], and delimiting the profile of the gingiva from the lateral perspective. The XCP Paralleling System (Dentsply, City of York, Pennsylvania) was then used [Figure 2]. The first radiograph was made in a frontal projection with the standard paralleling technique to confirm correct positioning of the lead plate and to evaluate any anatomic or pathologic alteration of the dental root [Figure 3]. The second radiograph was obtained from a lateral 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. It is necessary in all cases to confirm that the film lies exactly parallel to the long axis of the tooth.
|Figure 1: Gutta-percha point and lead plate aligned with the long axis of tooth|
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|Figure 2: XCP Paralleling System instruments in position, and correct position of all components is verified|
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|Figure 3: Frontal projection periapical radiograph shows lead foil positioned on the labial surface of right maxillary central incisor|
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The radiographs thus obtained were digitized using a scanner Epson perfection V700 Photo scanner, and the images were imported to X-ray vision assistant (XV3) software. 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. The following eight measurements were made on each radiograph:
- Length and thickness of lead plate: These measurements allowed evaluation of the dimensional distortion of the radiographic image in relation to the real size of the plate [Figure 4]
|Figure 4: Measurement of lead foil thickness, distance between cementoenamel junction and bone crest, and gingival sulcus depth|
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- Distance between cementoenamel junction (CEJ) and bone crest: To determine the location of the latter, the recommendations of Björn et al. were followed. Those authors identified the bone crest in radiographic images as the most coronal point of the bone plate where the width of the periodontal ligament is still visible [Figure 4]
- Depth of gingival sulcus: It was measured from gingival margin to the apical end of gutta-percha point [Figure 4]
- Thickness of connective attachment measured from the palatal face of the lead plate to the root surface: Measurement was made at three points: Bone crest level, middle third, and CEJ [Figure 5]
|Figure 5: Measurement of thickness of connective tissue attachment and free gingival thickness|
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- Thickness of free gingiva: It was measured at its base and at the middle third, from the buccal side of the gutta-percha point to the palatal face of the lead plate [Figure 5]
- Distance between bottom of gingival sulcus (apical end of gutta-percha point) and the bone crest: This dimension is equivalent to the biological width [Figure 6]
|Figure 6: Measurement of biologic width, bone plate thickness, and gingiva overlap on the enamel surface|
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- Thickness of bone plate: Measurement was done at bone crest level, middle third of the root, and apical third of the root [Figure 6]
- Distance from CEJ to marginal limit of gingiva: This measurement allowed evaluation of the amount of gingiva overlapping the enamel surface [Figure 6].
SPSS for Windows, Version 14.0. Chicago, SPSS Inc. was used to evaluate the gathered data. Mean, standard deviation (SD), and range were calculated for all clinical parameters. Spearman's rank correlation coefficient statistics were used.
| Results|| |
The gingival width measured in the region of the right maxillary central incisor is shown in [Table 1]. The dimensions of DGU obtained by PPRx technique are shown in [Table 2]. The mean distance between the CEJ and bone crest was 1.76 mm. However, both the range of values and the SD were scattered around the mean value, suggesting important variation of this dimension in the studied sample. The depth of the gingival sulcus measured from the radiograph was 1.39 mm on average. The mean thickness of the connective tissue attachment at the CEJ (1.56 mm) as well as at the middle third (1.54 mm) and bone crest level (1.48 mm) was similar although the SD was small. This seems to indicate less interindividual variability for this parameter. The mean thickness of the free gingiva at its middle third (0.93 mm) was less than at its base (1.09 mm), with small SDs in both cases. A mean biologic width of 1.95 mm was recorded although as above considerable scattering around the mean was observed.
The mean thickness of the buccal bone plate at the crest level, middle, and apical thirds showed little variation (0.47 mm, 0.77 mm, and 0.98 mm, respectively), with large ranges and SDs. The most extreme measurements were obtained at the apical third. The amount of gingiva overlapping the enamel surface was 1.76 mm on average, with highly variable and scattered results. Finally, an evaluation was also made of the possible relationship between the gingival width and the variables thickness of the connective attachment, biologic width, and depth of gingival sulcus. The results revealed a statistically significant relationship between gingival width and gingival sulcus depth (P = 0.06).
| Discussion|| |
The DGU has been described as a functional unit composed of the epithelial attachment and connective tissue attachment of the gingiva, both of which afford biological protection and invasion of this space may trigger inflammation that can lead to destruction of the attaching tissues of the tooth., It is important to establish an ideal dimension of the DGU during:,
- Placement of intrasulcular restorative margins,
- Clinical crown lengthening surgery,
- Surgical techniques for pocket elimination as well as for predicting the outcome of various mucogingival procedures,
- Placement of implants, and
- Treatment of delayed eruption process.
Although the clinical relevance of determining the dimensions of the structures of DGU is obvious, the literature makes little reference to this matter, probably because of the inherent difficulties involved. In published literature, majority of the studies have evaluated the dimensions of DGU by conventional histology on cadaver jaws , while few others used different methods such as injection needle or probe, ultrasonic devices,,,, bitewing radiographs, and soft-tissue cone-beam computed tomography.
Hence, the present study was aimed to evaluate an innovative radiographic technique, i.e., PPRx, for measuring the dimensions of the DGU without resorting to invasive procedures on the labial surfaces of anterior teeth in North Indian population, and to provide additional information on the dimensions of the DGU in humans.
Comparison of the results of the present study with the studies done by other authors has been shown in [Table 3]. Alpiste-Illueca  conducted a study on 88 periodontally healthy individuals to develop and evaluate a radiographic exploration technique, i.e., PPRx for measuring the dimensions of the DGU on the buccal surfaces of anterior teeth. Galgali and Gontiya  conducted a comparative study to evaluate an innovative radiographic exploration technique for measuring biological width and gingival thickness and compared the values obtained by the two methods were compared.
|Table 3: Comparison of values of dimensions of DGU (mean±SD in mm) with previous studies|
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The present study revealed that the mean distance between the CEJ and bone crest was 1.76 mm. The study done by Alpiste-Illueca  found its value to be 2.05 mm. In both studies, both the range of values and the SD were scattered around the mean value, suggesting important variation of this dimension. The depth of gingival sulcus was 1.39 mm in the present study, and this value coincides with the study conducted by Alpiste-Illueca, in which the gingival sulcus depth was found to be 1.30 mm.
The values for mean thickness of the connective tissue attachment at the CEJ, middle third, and bone crest level were almost similar with small SD. This seems to indicate less interindividual variability for this parameter, and similar results were found in studies conducted by Alpiste-Illueca, Eger et al., and Olsson et al. making this parameter the DGU component with the least interindividual variability. The thickness of gingiva measured at middle third and base by the PPRx technique in this study also falls into the range obtained by earlier studies.,
A mean biologic width of 1.95 mm was recorded in the present study. Various authors have found different values of biologic width as shown in [Table 4]. These results suggest that a value of 2.00 mm for biologic width should only be used as a theoretic reference. The mean thickness of the buccal plate at the crest level, middle, and apical thirds showed large ranges and SDs indicating wide interindividual variability. Finally, an evaluation was also made of the possible relationship between the gingival width and the variables thickness of the connective attachment, biologic width, and depth of gingival sulcus. The results revealed a statistically significant relationship between gingival width and gingival sulcus depth (P = 0.06) such as the findings of the study conducted by Alpiste-Illueca, in which statistically significant relationship was observed between the gingival width and gingival sulcus depth. In the same study, a statistically significant relationship was also observed between the gingival width and thickness of connective attachment, but in the same present, no correlation was found.
Therefore, it is clear that the PPRx technique affords a sufficient precision in the determination of the dimensions of the DGU. This study shows the PPRx technique to be a simple, concise, noninvasive, inexpensive, and reproducible technique that can be performed in the office without the need for special equipment and without any patient discomfort. The most important features of PPRx is that it can be used for research in vivo, in areas where serious difficulties have been encountered to date. It would be interesting to study the problems related to invasion of the biologic width and to intrasulcular restorative margins. Another potential research area would be the healing process and DGU stability following crown lengthening procedures to precisely locate and study the bone crest morphology and its location with respect to the CEJ and to evaluate the need for osteoplasty and osteotomy before surgery and the way in which the DGU organizes and evolves during the dental eruptive process.
The limitation of this technique is that it cannot be used in the posterior teeth and unhealthy periodontal tissues.
Taking into account the limitations of this study, it can be concluded that the dimensions of DGU are highly variable. Nevertheless, the thickness of both the connective tissue attachment and free gingiva showed less variation than the thickness of the bone plate and distance from CEJ to bone crest. The biologic width also exhibited important interindividual variability; although our mean results were similar to those of other authors, in the context of routine clinical practice, these dimensions should be determined on an individual basis. On the other hand, a relationship also appears to exist among gingival width and sulcus depth.
| Conclusions|| |
The dimensions and relationships of the structures of the DGU are essential aspects in many fields of dentistry, and this study describes a simple, novel, noninvasive, and a highly reproducible exploratory technique that may aid clinicians in the execution of procedures as an adjunct to traditional investigatory modalities.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
[Table 1], [Table 2], [Table 3], [Table 4]