Observation and determination of periodontal tissue profile using optical coherence tomography.

BACKGROUND AND OBJECTIVE: Diagnosis is a crucial step in periodontal treatment. The aim of this study was to evaluate the effectiveness of optical coherence tomography (OCT) for observation and determination of periodontal tissue profiles in vivo. MATERIAL AND METHODS: In experiment 1, refractive indices of purified water, porcine gingiva and human gingiva at 1330 nm were determined for the analysis of OCT images of periodontal tissues. In experiment 2, OCT examination was performed in the midlabial apico-coronal plane of mandibular anteriors in 30 Asian volunteers with healthy gingiva. Sulcus depth was measured on intra-oral photographs taken during probing. In the OCT images, the gingival, epithelial and connective tissue thickness, and the position of alveolar bone crest were determined and finally, the biologic width was measured. RESULTS: Refractive indices of purified water, porcine gingiva and human gingiva were 1.335, 1.393 and 1.397, respectively. Cross-sectional images of gingival epithelium, connective tissue and alveolar bone were depicted in real-time. The sulcular and junctional epithelium could be visualized occasionally. Laser penetration and reflection were limited to a certain depth with an approximate maximal imaging depth capability of 1.5 mm and OCT images of the periodontal structure were not clear in some cases. The average maximal thickness of gingiva and epithelium and biologic width at the mandibular anteriors were 1.06 ± 0.21, 0.49 ± 0.15 and 2.09 ± 0.60 mm, respectively. CONCLUSION: OCT has promise for non-invasive observation of the periodontal tissue profile in detail and measurement of internal periodontal structures including biologic width in the anterior region.

Non-Invasive Periodontal Probing Through Fourier-Domain Optical Coherence Tomography.

BACKGROUND: Periodontitis is a multifactorial and infectious disease that may result in significant debilitation. The aim of this study is to exploit two optical coherence tomography (OCT) systems operating in the Fourier domain at different wavelengths, 930 and 1,325 nm, for structural analysis of periodontal tissue in porcine jaws. METHODS: Five fresh porcine jaws were sectioned and stored in formalin before OCT analysis. Two- and three-dimensional OCT images of the tooth/gingiva interface were performed, and measurements of the gingival structures were obtained. The 930-nm OCT system operates in the spectral domain, whereas the 1,325-nm system is a swept-source model. Stereomicroscope images, the gold standard, were used for direct comparison. RESULTS: Through image analysis, it is possible to identify the free gingiva and the attached gingiva, the calculus deposition over tooth surfaces, and the subgingival calculus that enables the enlargement of the gingival sulcus. In addition, the gingival thickness and the gingival sulcus depth can be non-invasively measured, varying from 0.8 to 4 mm. CONCLUSIONS: Regarding the ability of the two OCT systems to visualize periodontal structures, the system operating at 1,325 nm shows a better performance, owing to a longer central wavelength that allows deeper tissue penetration. The results with the system at 930 nm can also be used, but some features could not be observed due to its lower penetration depth in the tissue.

Intraoral ultrasonography: development of a specific high-frequency probe and clinical pilot study.

Although ultrasonography is a non-invasive, inexpensive and painless diagnostic tool for soft tissue imaging, this technique is not currently used for oral exploration. Therefore, we developed a 25-MHz high-frequency ultrasound probe, specially designed for intraoral applications. This paper aims to present clinical intraoral ultrasound images actually interpretable, in order to identify the relevant applications of this novel tool and to design future oral studies. Two independent radiologists performed ultrasound examinations on three healthy volunteers. All the teeth were explored on the lingual and buccal sides (162 samples) to evaluate the ergonomics of the system and the visualisation of anatomic structures. Osseointegrated dental implants and a mucocele were also scanned. At the gingivodental junction of the maxillary and mandibular teeth, the device clearly identifies the tooth surfaces, the alveolar bone reflection with its surrounding subepithelial connective tissue of the gingiva and the gingival epithelia. The bone level and the thickness of soft tissue around the implant are measurable on the buccal and lingual sides. Therefore, intraoral ultrasonography provides additional morphological information that is not accessible by conventional dental x-rays. We propose a novel diagnostic tool that explores the biological width and is able to define the thin or thick nature of the gums. Moreover, intraoral ultrasonography may help to monitor precancerous lesions. This promising device requires large-scale clinical studies to determine whether it should remain a research tool or be used as a diagnostic tool for daily dental practice.

Evaluation of an innovative radiographic technique--parallel profile radiography--to determine the dimensions of dentogingival unit.

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 0.8-2.2 mm). 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.

Redefining the biologic width in severe, generalized, chronic periodontitis: implications for therapy.

BACKGROUND: Previous studies demonstrated significant variability in the histologic biologic width in periodontal health and mild periodontitis. The purpose of this study was to determine whether the previously established dimensions of the biologic width applied to subjects with severe, generalized, chronic periodontitis. METHODS: Twenty-eight subjects, aged 29 to 45 years, with severe, generalized, chronic periodontitis were included in the study. There were 18 males and 10 females, and 19 (68%) of the patients were smokers. Clinical and radiographic measures were taken by calibrated examiners. The clinical biologic width was determined from the most coronal level of clinical attachment to the crest of the alveolar bone for proximal surfaces only and compared to the histologic biologic width previously reported. RESULTS: The clinical biologic width in subjects with severe, generalized periodontitis was significantly greater than previously reported (P <0.001). For all evaluable proximal sites, the mean clinical biologic width was 3.95 mm versus the mean histologic biologic width of 2.04 mm. The greatest clinical biologic widths were seen with pockets <2 mm (5.02 +/- 2.48 mm; range: 1.60 to 9.00 mm) and 2 to 4 mm (4.16 +/- 1.32 mm; range: 0.20 to 6.40 mm). CONCLUSIONS: The mean clinical biologic width in subjects with severe, generalized, chronic periodontitis seemed to be significantly greater than the histologic biologic width previously reported for subjects not demonstrating significant periodontal pathology. In addition, sites with shallow probing depths demonstrated the greatest biologic width, suggesting that these sites may be at increased risk for losing clinically significant attachment during surgical procedures.

Dimensions of the dentogingival unit in maxillary anterior teeth: a new exploration technique (parallel profile radiograph).

This study sought to develop and evaluate a radiographic exploration technique (parallel profile radiograph [PPRx]) for measuring the dentogingival unit on the buccal surfaces of anterior teeth, and to provide additional information on the dimensions of the dentogingival unit in humans. In 88 periodontally healthy individuals, a PPRx was made of the maxillary left central incisor. Over these images, the components of the dentogingival unit were measured. PPRx was a highly reproducible exploratory technique. Mean dentogingival measurements on the buccal surfaces of the teeth were 2.05 +/- 0.87 mm for distance between the CEJ and bone crest; 2.00 +/- 0.72 mm for biologic width; 1.75 +/- 0.24 mm for thickness of connective tissue attachment; 1.12 +/- 0.24 mm for thickness of free gingiva at its base; 0.45 +/- 0.20 mm for thickness of bone plate at crest level; and 1.41 +/- 0.62 mm for gingival overlap on enamel surface. A statistically significant relationship was observed between free gingival width and thickness of connective attachment, and the depth of the gingival sulcus. These results corroborate the notion that the dimensions of the dentogingival unit are highly variable in humans. The thicknesses of both the connective tissue attachment and free gingiva, however, showed less variability than did the thickness of the bone crest, distance between CEJ and bone crest, and biologic width. The results suggest that gingival dimensions are correlated to dentogingival unit dimensions.

Quantification of periodontal attachment at single-rooted teeth.

The measurement process of attachment loss has been criticized in recent years. Problems with clinical interpretation, precision of the measurement, and statistical manipulation of the obtained data, are some of the problems associated with the present methodology. The purpose of the present study was to propose an alternative measurement process which addresses some of the existing problems by estimating the lost attachment surface area (LAS) and the remaining attachment surface area (RAS) from a combination of clinical measurements. The results show that a linear combination of several sources of clinical information can be used to predict RAS and LAS. A diagnostic model for LAS (R2 = 81.5%) predicts the square root of LAS with information obtained from bucco-lingual attachment level measurements, the radiographic lost attachment area, the gingivitis index and the radiographic tooth length. This model increases the precision of the estimate of LAS by a factor of 1.86 when compared to the estimate of LAS using only attachment level measurements. A diagnostic model for RAS (R2 = 75.5%) predicts the square root of RAS with the information obtained from the remaining radiographic attachment area, the gingivitis index and the mobility index. Both linear inference models are constructed with measurements of anatomical landmarks to avoid the discrepancy between anatomical and clinical measurements in the produced estimates. It is concluded that modeling of periodontal data provides a simple, inexpensive, and precise diagnostic tool for predicting the lost and the remaining periodontal attachment of single-rooted teeth. Measurement processes of this type could provide a convincing basis for the evaluation of clinical decisions and research questions.

Effect of nonsurgical periodontal therapy (VIII). Probing attachment changes related to clinical characteristics.

Individual sites with gain and loss of probing attachment were identified amongst 1688 proximal sites in non-molar teeth from 49 patients monitored for 24 months following oral hygiene instruction and root debridement. The distribution of sites with gain and loss of probing attachment was studied within each of the 49 subjects, for each of the 10 different tooth types treated, for teeth with and without root canal fillings, for mesial and distal surfaces, and for surfaces with and without the presence of root concavity/furcation involvement. Similarly, sites with gain and loss were related to the following measurements of the severity of the initial lesion: initial probing depth, radiographic bone score, depth of radiographic intraosseous defect, and radiographically widened periodontal ligament. The analyses indicated that subjects with a higher proportion of sites with probing attachment gain tended to have a lower proportion of sites with probing attachment loss. Sites with deep initial probing depth demonstrated a high incidence of gain and a low incidence of loss of probing attachment. All other investigated characteristics showed weak or no association with probing attachment change following therapy. This report indicates that the 24-month outcome of plaque control and root debridement in proximal surfaces of non-molar teeth is not compromised by the severity of the initial soft tissue or bony lesion.

Usefulness of subtraction radiography in the evaluation of periodontal therapy.

Subtraction radiography, a sensitive and accurate technique for identifying alveolar crestal change from standardized pairs of radiographs, is useful in monitoring periodontal therapy. One half of the radiographs were found to be appropriate for subtraction analysis using present technology for taking standardized radiographs. The criterion for usability was identical interpretation of subtraction images made in duplicate from a pair of radiographs. A set of radiographs was analyzed by subtraction radiography as well as by measurement of alveolar bone-crest height. Subtraction radiography was found to be more sensitive in detecting change. Whereas 53% pairs of radiographs showed a change on subtraction radiography, only 14% showed a change in crest height. Comparison of change by subtraction radiography and probing attachment level showed an overall correlation. Since these two measures assess different aspects of the periodontium, perfect correlation was not expected.

Radiographs in clinical periodontal trials.

Fifty-eight patients were selected from an ongoing study of periodontal therapy at The University of Michigan. Pre-and post-treatment series of full mouth radiographs obtained by conventional paralleling long cone technique were available. Mesial and distal radiographic bone height was scored using the technique developed by Björn et al. A total of 1416 teeth were scored from the itial radiographs, and subsequently at one, two, three, and four years after the treatment. Radiographic bone height scores were compared with level of attachment and pocket depth scores for the same teeth at the same time. Statistical significance and correlation coefficients were derived using computer analysis of the data. The data were analyzed using three different data groupings: individual teeth, patient means, and half-mouth treatment methods. High positive correlations were found between initial measurements of radiographic bone height and attachment level as well as pocket depth. The correlations between changes in measurements of radiographic bone height and attachment level after treatment were markedly lower but are statistically significant. A highly significant correlation between radiographic bone heights and measurements of attachment level also appeared in follow-up data one to four years after treatment. The method of data grouping resulted in different correlation coefficients. Highest correlations were found if the data were pooled for patients. Lowest correlations were found if the data for individual teeth were analyzed. When the data were combined to produce patient scores, sample variation is reduced and correlations increase in magnitude. The generally high correlations between radiographic bone height and attachment level scores before and after treatment tend to confirm the fact that radiographic assessment of alveolar bone height using the method of Björn et al. can provide fairly accurate assessment of interproximal periodontal support.