Depth-force patterns of periodontal probing. Attachment-gain in relation to probing force

Artificial intelligence and personalized diagnostics in periodontology: A narrative review

Periodontal diseases pose a significant global health burden, requiring early detection and personalized treatment approaches. Traditional diagnostic approaches in periodontology often rely on a "one size fits all" approach, which may overlook the unique variations in disease progression and response to treatment among individuals. This narrative review explores the role of artificial intelligence (AI) and personalized diagnostics in periodontology, emphasizing the potential for tailored diagnostic strategies to enhance precision medicine in periodontal care. The review begins by elucidating the limitations of conventional diagnostic techniques. Subsequently, it delves into the application of AI models in analyzing diverse data sets, such as clinical records, imaging, and molecular information, and its role in periodontal training. Furthermore, the review also discusses the role of research community and policymakers in integrating personalized diagnostics in periodontal care. Challenges and ethical considerations associated with adopting AI-based personalized diagnostic tools are also explored, emphasizing the need for transparent algorithms, data safety and privacy, ongoing multidisciplinary collaboration, and patient involvement. In conclusion, this narrative review underscores the transformative potential of AI in advancing periodontal diagnostics toward a personalized paradigm, and their integration into clinical practice holds the promise of ushering in a new era of precision medicine for periodontal care.

Influences of race/ethnicity in periodontal treatment response and bacterial distribution, a cohort pilot study

Objectives

Periodontitis disproportionately affects different racial and ethnic populations. We have previously reported the higher levels of Porphyromonas gingivalis and lower ratios of Streptococcus cristatus to P. gingivalis may contribute to periodontal health disparities. This prospective cohort study was designed to investigate if ethnic/racial groups responded differently to non-surgical periodontal treatment and if the treatment outcomes correlated to the bacterial distribution in patients with periodontitis before treatment.

Methods

This prospective cohort pilot study was carried out in an academic setting, at the School of Dentistry, University of Texas Health Science Center at Houston. Dental plaque was collected from a total of 75 African Americans, Caucasians and Hispanics periodontitis patients in a 3-year period. Quantitation of P. gingivalis and S. cristatus was carried out using qPCR. Clinical parameters including probing depths and clinical attachment levels were determined before and after nonsurgical treatment. Data were analyzed using one-way ANOVA, the Kruskal-Wallis test, the paired samples t-test and the chi-square test.

Results

The gains in clinical attachment levels after treatment significantly differed amongst the 3 groups-Caucasians responded most favorably, followed by African-Americans, lastly Hispanics, while numbers of P. gingivalis were highest in Hispanics, followed by African-Americans, and lowest in Caucasians (p = 0.015). However, no statistical differences were found in the numbers of S. cristatus amongst the 3 groups.

Conclusion

Differential response to nonsurgical periodontal treatment and distribution of P. gingivalis are present in different ethnic/racial groups with periodontitis.

Cone-Beam Computed Tomography for Detection of Intrabony and Furcation Defects: A Systematic Review Based on a Hierarchical Model for Diagnostic Efficacy

BACKGROUND

The aim of this review is to assess the diagnostic efficacy of cone-beam computed tomography (CBCT) for the diagnosis of and/or treatment planning for intrabony and furcation defects, using a well-known six-tiered hierarchical model for diagnostic efficacy.

METHODS

The MEDLINE, EMBASE, and Cochrane Library bibliographic databases were searched until August 2015 for studies evaluating CBCT imaging for the diagnosis of and/or treatment planning for intrabony and/or furcation defects. The search strategy was restricted to English language publications using the combination of MeSH terms, free terms, and key words.

RESULTS

The search strategy yielded 16 publications that qualitatively or quantitatively evaluated the use of CBCT for the detection of intrabony and/or furcation defects and how CBCT influenced the diagnosis and/or treatment plan. According to Quality Assessment of Studies of Diagnostic Accuracy-2, all included studies were medium to low risk of bias. The review identified only one study that investigated the societal efficacy, and none evaluated the patient outcome efficacy or therapeutic efficacy. One study investigated the diagnostic thinking efficacy. All other included studies investigated the diagnostic accuracy of CBCT.

CONCLUSIONS

From the assessed studies, it can be concluded that there is not sufficient scientific evidence to justify the use of CBCT for the diagnosis of and/or treatment planning for intrabony and furcation defects. Furthermore, the effectiveness of CBCT for such diagnostic tasks has been assessed only at low diagnostic efficacy levels.

In-vitro accuracy and reproducibility evaluation of probing depth measurements of selected periodontal probes

AIM

The purpose of the present in vitro study was to measure the accuracy and reproducibility of three periodontal probes. To eliminate environment- or examiner-related probing errors, two aluminum blocks with predrilled holes of varying depths were examined by participants who had been trained in probing before the study. This methodology improved the likelihood that any probing errors identified were generated by the probes themselves.

MATERIALS AND METHODS

Three probes, Williams 14 W (Hu-Friedy Mfg. Co., LLC, UK), Chapple UB-CF-15 (Implantium, Shrewsbury, UK), and Vivacare TPS (Ivoclar Vivadent, Enderby, UK), were randomly distributed to 23 participants (9 males and 14 females; mean age: 31.35 years). Participants measured 30 holes in two aluminum blocks, average 20 days, SD = 341.05. For each hole, the mean measured depth was calculated for each participant and compared to the true depth. Intra- and inter-examiner accuracy and reproducibility for each of the duplicate measurements were calculated. Data were analyzed by paired-samples t-test with the SPSS 18 software package (IBM Portsmouth, UK). A p-value <0.05 indicated statistical significance. Tables were constructed from the data.

RESULTS

When used by participants, the Williams 14 W probe was reproducible but not necessarily accurate; Vivacare TPS was neither accurate nor reproducible; and Chapple UBCF-15 was both accurate and reproducible.

CONCLUSION

Depth measurements with the Chapple UB-CF-15 probe were more accurate and reproducible compared to measurements with the Vivacare TPS and Williams 14 W probes. This in vitro model may be useful for intra-examiner calibration or clinician training prior to the clinical evaluation of patients or in longitudinal studies involving periodontal evaluation.

Methodological issues in epidemiological studies of periodontitis--how can it be improved?

Background

This position paper was commissioned by the European Association of Dental Public Health, which has established six working groups to investigate the current status of six topics related to oral public health. One of these areas is epidemiology of periodontal diseases.

Methods

Two theses "A systematic review of definitions of periodontitis and the methods that have been used to identify periodontitis" [1] and "Factors affecting community oral health care needs and provision" [2] formed the starting point for this position paper. Additional relevant and more recent publications were retrieved through a MEDLINE search.

Results

The literature reveals a distinct lack of consensus and uniformity in the definition of periodontitis within epidemiological studies. There are also numerous differences in the methods used. The consequence is that data from studies using differing case definitions and differing survey methods are not easily interpretable or comparable. The limitations of the widely used Community Periodontal Index of Treatment Need (CPITN) and its more recent derivatives are widely recognized. Against this background, this position paper reviews the current evidence base, outlines existing problems and suggests how epidemiology of periodontal diseases may be improved.

Conclusions

The remit of this working group was to review and discuss the existing evidence base of epidemiology of periodontal diseases and to identify future areas of work to further enhance it.

Probing pressure, a highly undervalued unit of measure in periodontal probing: a systematic review on its effect on probing pocket depth

AIM

To investigate the influence of probing pressure on the probing pocket depth (PPD) in diseased and healthy periodontal tissue conditions through a systematic review. In addition, to facilitate comparison of the study outcomes, an attempt was made to provide a correction factor that compensates for the different probing pressures used.

MATERIAL AND METHODS

The MEDLINE-PubMed and Cochrane Central Register of controlled trails (Central) were searched up to June 2008 to indentify appropriate studies.

RESULTS

The search yielded 3032 titles and abstracts. In total, five papers fulfilled the eligibility criteria. These studies provided data with probing pressures ranging from 51 to 995 N/cm(2). For the evaluation of the results a distribution was made between diseased and healthy/treated sites. The incremental change in PPD in healthy/treated sites decreased as the pressure increased above 398 N/cm(2). In diseased sites, this phenomenon was already present at pressures above 100 N/cm(2). At healthy/treated sites, a mean increase of PPD of 0.002 mm per increase of 1 N/cm(2) in probing pressure could be calculated whereas at diseased sites this value amounted to 0.004 mm.

CONCLUSION

The results show that with increasing probing pressure, the PPD increases. The dimensions of the increase are dependent on the periodontal tissue conditions.

A thin or thick probe handle: does it make a difference?

OBJECTIVES

The aim of the present study was to assess the probing force exerted when using two manual periodontal probes with different handle diameters in hands of different dental professionals.

METHODS

For this study two periodontal probes with handle diameters of 54 and 92 mm were used. The 11 subjects responsible for the measurements were periodontists, postgraduate periodontal students and dental hygienists. Per measurement session, 20 measurements were performed by each subject. Each probe was used 10 times. After the first baseline measurement session, a second session was performed 1 week later and a last third session another 3 weeks later. Orders for using each probe were randomized for each subject and each session.

RESULTS

The mean overall force with the thin probe was 55.2 g and with the thick probe 59.4 g. The difference of 4.2 g between the two probe types was found to be statistically significant (P = 0.041).

CONCLUSION

The present study showed that the diameter of the probe handle also had an effect on the force exerted with a periodontal probe. However, the clinical relevance of this difference may be minor, when considering the interindividual variance of forces exerted when probing.

Comparison of two automated periodontal probes and two probes with a conventional readout in periodontal maintenance patients

AIM

The aim of the present study was to test in periodontal maintenance patients whether the systems for pressure control that have been commercially developed contribute to more reproducible probing depth measurements as compared with a manual probe.

MATERIAL AND METHODS

In 12 patients duplicate measurements were made at day 0 and 1 week later. In each patient four teeth with the deepest pockets were measured at six sites. In total 288 sites were available for comparisons. The Florida Probe (FP) (159 N/cm(2)), the Jonker Probe (JP) (153 N/cm(2)), the Brodontic probe (BP) (255 N/cm(2)) and the manual probe (MP) were used in a randomized scheme.

RESULTS

Mean probing measurements showed for the FP and the JP lower recordings than for the BP and manual probe. The FP, the BP and the MP showed no differences between the duplicate measurements, except for the JP where the second measurement was deeper. Correlation coefficients between measurements at day 0 and 1 week show for the BP and the MP are 0.90 and 0.89, respectively, while for the FP and the JP they are 0.76 and 0.75, respectively.

CONCLUSION

The BP and the MP appear to be reliable tools for reproducible pocket depth measurements in periodontal maintenance patients.

Evaluation of a new periodontal probe tip design. A clinical and in vitro study

AIMS

In the search for an accurate periodontal probe which does not frequently penetrate the pocket base, a new tip has been designed which is flattened, and of 1 mm width and 0.45 mm thickness. This study aimed to evaluate the physico-mechanical and clinical properties of this probe (test) in comparison to a conventional 0.5 mm circular probe (control).

METHODS

Photoelastic stress analysis was undertaken for test and control probe tips at 3.15 and 5 N loads. To assess probing validity, the clinical probing depth with each probe (0.25 N force) at 125 sites on 27 teeth (27 subjects), was compared with the post-extraction connective tissue level measurement. Also evaluated were probing reproducibility (1200 sites in 25 subjects) and patient comfort (30 subjects).

RESULTS

Using photoelastic stress analysis, the test probe demonstrated lower stresses and less local stress concentration than the control. Clinically, the test probe measured close to the post-extraction gold standard in greater frequency than the control - 26 versus 11 readings (21% versus 9%) exactly matched, and 90 versus 67 (72% versus 54%) were within +/-0.5 mm of the laboratory measurement. The test probe was, on average, 0.13 mm coronal to the connective tissue attachment level, whereas the control penetrated 0.27 mm past this level. The intraclass correlation between clinical and laboratory readings was greater for the test than the control (r=0.81 and 0.74, respectively). Although the control probe overestimated probing depth more markedly at bleeding (0.41 mm) than at non-bleeding (0.15 mm) sites, the relative position of the test probe hardly differed with inflammatory status (-0.11 and -0.14 mm, respectively). Each probe demonstrated good clinical reproducibility. However, the test probe examination was more comfortable for the patient.

CONCLUSION

This new periodontal probe tip appears to have greater validity, good reproducibility and produces less patient discomfort.

Periimplant probing: positives and negatives

Periodontium in normal dentition is not as it is surrounding an implant area. Thus, periodontal probing with normal dentition is not similar to periimplant probing. The periimplant probing protocol should be different from periodontal probing because of inherent anatomical differences. The aim of this paper is to review the topics related to periimplant probing and to draw inferences to develop a periimplant probing protocol.

Healing after standardized clinical probing of the perlimplant soft tissue seal: a histomorphometric study in dogs

BACKGROUND/AIMS

Clinical probing of the soft tissues around oral implants has become a frequently used parameter for clinical monitoring. However, the healing of the disruption of the soft tissue seal as a result of probing has not yet been studied. The purpose of this study was to evaluate the healing events in the periimplant mucosal tissues following standardized clinical probing.

MATERIALS AND METHODS

In three foxhounds the mandibular premolars were extracted and, after 3 months of healing, TPS screw-shaped implants (ITO Dental Implant System) were installed. A plaque control regimen was performed throughout the duration of the experiment. After 3 months of healing of the transmucosal implants, clinical implant stability and healthy periimplant mucosal tissues with mostly absence of bleeding on probing were obtained. Clinical probing of the mesial and distal implant sites was performed immediately before 1, 2, 3, 5 and 7 days prior to the sacrifice of the animals. A specially manufactured titanium cylinder with a mesial and distal groove was fixed to the implants to standardize the insertion geometry of a pressure-sensitive probe (0.2-0.25 N, tip diameter 0.45 mm). The distances from the alveolar crest to the coronal border of the connective tissue adaptation to the implant and the length of the epithelial attachment were measured histomorphometrically in nondecalcified ground sections. The buccal and lingual aspects of the implants were used to determine the components of the biological width in unprobed control sites.

RESULTS

The probe caused a separation between the surface of the implant and the junctional epithelium, but not within the connective tissue adaptation. In general, the probe tip was located at the most coronal level of the supracrestal connective tissue as determined histologically. By 1 day after separation of the periimplant mucosal tissue by probing, an epithelial attachment of approximately 0.5 mm in the apico-coronal direction was observed. The length of the epithelial adaptation showed a tendency to increase over time (day 2: 1.15 mm, day 3: 1.52 mm), and was complete at day 5 (1.92 mm). At the unprobed sites the epithelial attachment showed a mean length of 1.69 mm. Inflammatory infiltrates were practically nonexistent, indicating the absence of tissue trauma or infection as a result of probing.

CONCLUSIONS

Clinical probing around osseointegrated implants does not appear to have detrimental effects on the soft tissue seal and, hence, does not seem to jeopardize the longevity of oral implants. The 'healing of the epithelial attachment' seems to be complete 5 days after clinical probing.

Periodontal probing in comparison to diagnosis by CT-scan

AIM

To compare clinical periodontal probing and the corresponding CT-evaluation of the loss of bone.

METHOD

639 measurement sites were studied on 95 periodontal sites. The measured length was the distance between the cemento-enamel junction (CEJ) and the pocket base on probing and the bone base of the pocket on the CT-analysis. Additionally, a comparison of the diagnostic potential of both methods regarding the furcation involvement was made.

RESULTS

Clinical probing depths showed a mean value of 2.6+/-2.0 mm, while the CT-measurements exhibited a figure of 4.2+/-2.3 mm. In 49.5% of the measured sites, the difference between clinical and CT-measurement was 2mm or higher. The greatest differences between the measured values were found on the buccal and lingual sites (P=0.0004). The narrower the vertical bone defects in the CT (angle in coronal direction), the greater were the differences between the clinical probing depths and the measurements carried out on the CT (P=0.02). Clinically, in 31% of the cases the furcation involvement was underestimated or not identified at all.

CONCLUSION

Computed tomography imaging techniques could be beneficial in the field of periodontal diagnosis. The results underscore the higher accuracy of the CT-technique, compared with clinical probing, while assessing periodontal breakdown and its marked superiority in the diagnosis of furcation areas, compared to the clinical examinations performed.

Periodontal probing: probe tip diameter

BACKGROUND

Periodontal probing is one of the most common methods used in diagnosing periodontal disease. The purpose of this study was to determine the importance of the diameter of periodontal probing tips in diagnosing and evaluating periodontal disease.

METHODS

The literature discussing periodontal probe diameters in human, dog, and monkey studies was reviewed and compared. Tip diameters varied from 0.4 to over 1.0 mm in these studies. Probe advancement between the gingiva and the tooth is determined by the pressure exerted on the gingival tissues and resistance from the healthy or inflamed tissue. The pressure is directly proportionate to the force on the probe and inversely proportionate to the probe tip diameter. The larger probing diameters reduced probe advancement into inflamed connective tissue. This effect of change in probe diameter reduced the pressure in a greater manner than an increase of similar change in probe force.

RESULTS

In the studies reviewed, the pressure used to place the probe tip at the base of the periodontal sulcus/pocket was approximately 50 N/cm2 and at the base of the junctional epithelium, 200 N/cm2. A tip diameter of 0.6 mm was needed to reach the base of the pocket. Clinical inflammation did not necessarily reflect the severity of histological inflammation, and the recordings may not illustrate probing depth. Furthermore, probing depth did not identify anatomical locations at the base of the pocket.

CONCLUSIONS

Probe tips need to have a diameter of 0.6 mm and a 0.20 gram force (50 N/cm2) to obtain a pressure which demonstrates approximate probing depth. This pressure was needed to measure the reduction of clinical probing depth, which included formation of a long junctional epithelium as a result of therapy. In addition, different forces or diameter tips are needed to measure healthy or inflamed histological periodontal probing depths.

Pain threshold values during periodontal probing: assessment of maxillary incisor and molar sites

Probing pain threshold (PPT) assessments were conducted in the facial and oral sulci of maxillary central incisors and first molars of 10 periodontally healthy adults. All subjects were systemically healthy, free of pain, and reported no current medication usage. A computer-linked electronic probe, modified to deliver steadily increasing forces up to 200 grams, was used to collect the data. The system contained a subject operated "off-switch" which, upon activation, signaled the computer to record the subject's PPT. Assessments of each subject's PPTs were conducted on 3 separate occasions at 7-day intervals. Results indicated that the facial sulci of the incisors were the most pain sensitive. They displayed a mean PPT of 50.9 +/- 26.6 grams. The oral sulci of the incisors exhibited a mean PPT of 76.5 +/- 45.2 grams. Facial and oral sulci of the molars evidenced mean PPT values of 102.6 +/- 52.1 grams and 113.5 +/- 51.3 grams, respectively. These data suggest that sulci associated with incisor teeth are nearly twice as pain sensitive as sulci associated with molar teeth. In addition, facial sulci are significantly more pain sensitive than oral sulci. Data did not indicate a visit effect nor a side-of-mouth effect on PPT values.

Effect of the NSAID flurbiprofen on remodelling after periodontal surgery

The aim of the present experiment was to assess the effect of the administration of the NSAID flurbiprofen (Froben) on tissue healing after periodontal surgery. Sites from patients with the same treatment modality (modified Widman flap) but receiving a placebo drug and sites within each patient not exposed to surgery served as controls. Nineteen patients suffering from moderate to severe periodontal disease were recruited and they signed informed consent forms. These patients required periodontal surgery as assessed at the periodontal re-evaluation. The sites chosen for the study were all diagnosed with PPD > or = 5 mm and were bleeding on probing. During the healing phase 10 patients received 50 mg Froben 3 times per day for 30 d whereas 9 patients received a placebo drug. Two sites with PPD > or = 5 mm after initial therapy and bleeding on probing served as surgical sites, whereas 2 similar sites were not exposed to surgery. The study design was set up double-blind. The radiographic examination consisted of 2-4 standardized vertical bitewings obtained at the periodontal re-evaluation (BL) at 1, 3 and 6 months post-surgically for digital subtraction and computer assisted densitometric image analysis (CADIA). The regions of interest analysed were mesial or distal crestal sites. Minimal remodelling activity was observed radiographically after periodontal surgery in both patient groups. There were no statistically significant differences between the four groups of sites regarding the mean changes in density when analysing the pairs of radiographs 0-1, 0-3, 0-6 months. A frequency analysis was performed to list the number of sites with different ranges of density change. No differences in the distributions of the numbers of sites were observed when comparing the 4 site groups (Kolmogorov-Smirnov, p > 0.05). A significant reduction of the probing pocket depth and a significant amount of clinical attachment gain was noted at the surgically treated sites irrespective of whether the patients had used flurbiprofen or placebo. Whereas the pathways leading to bone resorption in periodontally diseased sites have been shown, in other studies, to be influenced by NSAID, the results of the present study could not justify general administration of Froben for the purpose of reduction of bone resorption after periodontal surgical procedures in patients with adult periodontitis.

Clinical evaluation of tine shape of 3 periodontal probes using 2 probing forces

The objective of this study was to evaluate the effect of the tine shape of 3 different periodontal probes. One tapered, one parallel-sided and one WHO-probe tine, each with a diameter of 0.5 mm at the tip, were mounted in hinged handles exerting a constant probing force (Brodontic). The handles were adjusted to either 0.25 N (127 N/cm2) or 0.5 N (255 N/cm2). 12 patients with moderate to severe periodontitis were measured after supra- and subgingival debridement, using all 6 possible tine/force combinations in 3 sessions. In each session one tine/force combination was used in the 1st and 3rd quadrants, and another tine/force combination in the 2nd and 4th quadrant. The measurements in the same quadrants could therefore be used for comparisons within the same site. The selection for the 2 quadrants in which a given tine/force combination was to be used, was randomised. Calculations of differences (mean per patient) between probing measurements show that the WHO tine yields deeper recording than the parallel/sided and tapered tines, both at 127 N/cm2 and 255 N/cm2. We conclude that in addition to probing force, the tine shape of a periodontal probe is of significant importance for the recorded probing depth.

Periodontal diagnosis in treated periodontitis. Why, when and how to use clinical parameters

The objective of clinical periodontal diagnosis in maintenance patients is to monitor the risk for periodontal disease progression. Risk for progression should be continuously monitored at the patient, tooth and site level at each recall appointment. At the patient level, the significance of systemic diseases, cigarette smoking, compliance with the recall program, loss of support in relation to the patient's age, full mouth plaque and/or bleeding scores, and prevalence of residual pockets are of key importance. At the tooth and tooth-site levels, residual periodontal support, inflammatory parameters and their persistence, presence of ecological niches with difficult access such as furcations, and presence of iatrogenic factors have to be put into proportion with the patient's overall risk profile. The information gathered by clinical monitoring and continuous multilevel risk assessment facilitates an immediate appreciation of the periodontal health status of an individual and the possible risk for further infection and/or disease progression in the dentition and at a particular tooth or site.

Effect of gingival wall on resistance to probing forces

This study was conducted to determine whether the gingival tissue lateral to the periodontal sulcus contributes resistance to the advancement of a periodontal probe tip into the sulcus under different applied pressures. An electromechanical device was used to advance a probe tip 0.6 mm in diameter into the facial sulcus at a constant speed until resisting forces of 0.70 N were encountered. The device registered the resisting force and probe advancement simultaneously. The gingiva of all 2nd incisors, 2nd premolars, and 1st molars of 4 young adult male beagle dogs were tested. After the first measurement, the buccal gingiva of experimental sites were incised mesiodistally from the gingival margin to the alveolar crest and the sulcus was reprobed. 2 experimental and control quadrants were selected randomly resulting in 6 sets of both experimental and control data from each animal. The data were analyzed with analysis of variance. The analysis demonstrated significant variation from site to site, and dog to dog; therefore, only changes between the 1st and 2nd probings at the same sites could be compared. Less variability of probing distance in different animals occurred at higher forces; however, the incision had a significant effect on probing distance at these forces. The pressure at which probing distance had less variability among animals and least affected when the gingival sulcular wall was incised was estimated to be 106 N/cm2. This corresponds to 30 g force on the 0.6 mm diameter probe.

Histological location of a standardized periodontal probe in man

The purpose of this study was to locate the position of the periodontal probe tip using a pressure of 126 N/cm2 (force of 0.30N using a round periodontal probe tip with a diameter of 0.55 mm). The influence of gingival inflammation on this position was also studied. Subjects with three levels of periodontal health and disease were entered into the study and each contributed one experimental tooth. At each site a standardized probing system was used to place a probe into a clinical pocket. The probe tip was luted to the test tooth surface. The tooth with its gingival tissue and probe tip was extracted, fixed, and processed for histological measurements. Distances in mm were obtained from the cemento-enamel junction (CEJ) to the probe tip, to the base of the crevice/pocket, and to the most coronal connective tissue attachment. Analysis of the data indicated that clinical inflammation was not a factor in the placement of the probe tip at crevice/pocket's landmarks relative to the CEJ; however variability of probing may have caused the non-significance. The probing system placed the probe tip 0.66 mm apical to the base of the crevice/pocket and 0.06 mm coronal to the most coronal connective tissue attachment. These conclusions corroborated the results of the previous study in dogs which predicted probe placement of 0.44 mm apical to the base of the crevice using the standardized pressure of this probing system.

Remodelling of periodontal tissues adjacent to sites treated according to the principles of guided tissue regeneration (GTR)

The aim of the present study was to assess the remodelling of alveolar bone adjacent to periodontal sites following therapy according to the principles of guided tissue regeneration (GTR) using computer-assisted densitometric image analysis (CADIA), and to compare the radiographic results to traditional clinical parameters. As required for digital subtraction analyses, periodically reproducible radiographs were obtained using a modification of the Rinn System and individual acrylic bite blocks for periodical identical radiographs. Ideally, a digital subtraction image from a site where absolutely no change in density had occurred would show a perfect cancellation of the structures. An average grey level value of 128 (the middle of the digitizer grey level range set by software) would show up at each pixel. Areas with grey levels < 128 in the subtraction image would indicate loss in density and grey levels > 128 would indicate increase in density. Within the subtraction images, areas were defined using the cursor to draw "regions of interest" (ROI) projected on the bony defect exposed to GTR covering the crestal bone as well as the region of potential "bonefill". The mean, median, the standard deviation and range of the grey levels of pixels within a particular ROI were calculated. Similarly sized ROI were drawn in bone areas not exposed to the GTR procedure serving as controls. The differences in the mean grey levels of all pixels within a particular ROI between the baseline, 3 and 12 months images were calculated for documentation of gain or loss in density. From 14 patients, standardized radiographs were available from baseline, 3 months and 12 months postsurgically, depicting one infraosseous defect before and after treatment according to the principles of GTR. The densitometric changes observed in these defects were compared to the clinically assessed changes measured at the site with the deepest baseline pocket depth. A mean clinical attachment gain of 2.36 mm after 3 and 3.22 mm after 12 months was measured. This was associated with a mean reduction in the PPD amounting to 3.36 mm and 3.79 mm, respectively. The changes in the level of the FGM were rather small considering the deep original mean PPD of 7.07 mm. Over the first months, a mean recession of 1.14 mm was observed which was followed by a coronal displacement of 0.43 mm. With respect to the remodelling of the alveolar bone adjacent to the defects assessed by means of CADIA, the most pronounced changes occurred when comparing the baseline to the 12 months radiographs.(ABSTRACT TRUNCATED AT 400 WORDS)