Intraclass correlations of periodontal measurements

Adjunctive systemic antimicrobials for the non-surgical treatment of periodontitis

BACKGROUND

Systemic antimicrobials can be used as an adjunct to mechanical debridement (scaling and root planing (SRP)) as a non-surgical treatment approach to manage periodontitis. A range of antibiotics with different dosage and combinations are documented in the literature. The review follows the previous classification of periodontitis as all included studies used this classification.

OBJECTIVES

To assess the effects of systemic antimicrobials as an adjunct to SRP for the non-surgical treatment of patients with periodontitis.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases to 9 March 2020: Cochrane Oral Health's Trials Register, CENTRAL, MEDLINE, and Embase. The US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) which involved individuals with clinically diagnosed untreated periodontitis. Trials compared SRP with systemic antibiotics versus SRP alone/placebo, or with other systemic antibiotics.

DATA COLLECTION AND ANALYSIS

We selected trials, extracted data, and assessed risk of bias in duplicate. We estimated mean differences (MDs) for continuous data, with 95% confidence intervals (CIs). We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included 45 trials conducted worldwide involving 2664 adult participants. 14 studies were at low, 8 at high, and the remaining 23 at unclear overall risk of bias. Seven trials did not contribute data to the analysis. We assessed the certainty of the evidence for the 10 comparisons which reported long-term follow-up (≥ 1 year). None of the studies reported data on antimicrobial resistance and patient-reported quality of life changes. Amoxicillin + metronidazole + SRP versus SRP in chronic/aggressive periodontitis: the evidence for percentage of closed pockets (MD -16.20%, 95% CI -25.87 to -6.53; 1 study, 44 participants); clinical attachment level (CAL) (MD -0.47 mm, 95% CI -0.90 to -0.05; 2 studies, 389 participants); probing pocket depth (PD) (MD -0.30 mm, 95% CI -0.42 to -0.18; 2 studies, 389 participants); and percentage of bleeding on probing (BOP) (MD -8.06%, 95% CI -14.26 to -1.85; 2 studies, 389 participants) was of very low certainty. Only the results for closed pockets and BOP showed a minimally important clinical difference (MICD) favouring amoxicillin + metronidazole + SRP. Metronidazole + SRP versus SRP in chronic/aggressive periodontitis: the evidence for percentage of closed pockets (MD -12.20%, 95% CI -29.23 to 4.83; 1 study, 22 participants); CAL (MD -1.12 mm, 95% CI -2.24 to 0; 3 studies, 71 participants); PD (MD -1.11 mm, 95% CI -2.84 to 0.61; 2 studies, 47 participants); and percentage of BOP (MD -6.90%, 95% CI -22.10 to 8.30; 1 study, 22 participants) was of very low certainty. Only the results for CAL and PD showed an MICD favouring the MTZ + SRP group. Azithromycin + SRP versus SRP for chronic/aggressive periodontitis: we found no evidence of a difference in percentage of closed pockets (MD 2.50%, 95% CI -10.19 to 15.19; 1 study, 40 participants); CAL (MD -0.59 mm, 95% CI -1.27 to 0.08; 2 studies, 110 participants); PD (MD -0.77 mm, 95% CI -2.33 to 0.79; 2 studies, 110 participants); and percentage of BOP (MD -1.28%, 95% CI -4.32 to 1.76; 2 studies, 110 participants) (very low-certainty evidence for all outcomes). Amoxicillin + clavulanate + SRP versus SRP for chronic periodontitis: the evidence from 1 study, 21 participants for CAL (MD 0.10 mm, 95% CI -0.51 to 0.71); PD (MD 0.10 mm, 95% CI -0.17 to 0.37); and BOP (MD 0%, 95% CI -0.09 to 0.09) was of very low certainty and did not show a difference between the groups. Doxycycline + SRP versus SRP in aggressive periodontitis: the evidence from 1 study, 22 participants for CAL (MD -0.80 mm, 95% CI -1.49 to -0.11); and PD (MD -1.00 mm, 95% CI -1.78 to -0.22) was of very low certainty, with the doxycycline + SRP group showing an MICD in PD only. Tetracycline + SRP versus SRP for aggressive periodontitis: we found very low-certainty evidence of a difference in long-term improvement in CAL for the tetracycline group (MD -2.30 mm, 95% CI -2.50 to -2.10; 1 study, 26 participants). Clindamycin + SRP versus SRP in aggressive periodontitis: we found very low-certainty evidence from 1 study, 21 participants of a difference in long-term improvement in CAL (MD -1.70 mm, 95% CI -2.40 to -1.00); and PD (MD -1.80 mm, 95% CI -2.47 to -1.13) favouring clindamycin + SRP. Doxycycline + SRP versus metronidazole + SRP for aggressive periodontitis: there was very low-certainty evidence from 1 study, 27 participants of a difference in long-term CAL (MD 1.10 mm, 95% CI 0.36 to 1.84); and PD (MD 1.00 mm, 95% CI 0.30 to 1.70) favouring metronidazole + SRP. Clindamycin + SRP versus metronidazole + SRP for aggressive periodontitis: the evidence from 1 study, 26 participants for CAL (MD 0.20 mm, 95% CI -0.55 to 0.95); and PD (MD 0.20 mm, 95% CI -0.38 to 0.78) was of very low certainty and did not show a difference between the groups. Clindamycin + SRP versus doxycycline + SRP for aggressive periodontitis: the evidence from 1 study, 23 participants for CAL (MD -0.90 mm, 95% CI -1.62 to -0.18); and PD (MD -0.80 mm, 95% CI -1.58 to -0.02) was of very low certainty and did not show a difference between the groups. Most trials testing amoxicillin, metronidazole, and azithromycin reported adverse events such as nausea, vomiting, diarrhoea, mild gastrointestinal disturbances, and metallic taste. No serious adverse events were reported.

AUTHORS' CONCLUSIONS

There is very low-certainty evidence (for long-term follow-up) to inform clinicians and patients if adjunctive systemic antimicrobials are of any help for the non-surgical treatment of periodontitis. There is insufficient evidence to decide whether some antibiotics are better than others when used alongside SRP. None of the trials reported serious adverse events but patients should be made aware of the common adverse events related to these drugs. Well-planned RCTs need to be conducted clearly defining the minimally important clinical difference for the outcomes closed pockets, CAL, PD, and BOP.

Relationship Between Periodontal Screening and Recording Index Scores and Need for Periodontal Access Surgery

BACKGROUND

The validity of using pretreatment Periodontal Screening and Recording (PSR) index sextant scores to estimate periodontal access surgery needs is evaluated in patients with chronic periodontitis before and after completion of non-surgical periodontal therapy.

METHODS

In 110 adults, pretreatment probing data identified 486 sextants with PSR scores of 4 and 125 sextants with PSR scores of 3. Periodontal access surgery needs for all sextants were determined prior to treatment and after completion of non-surgical periodontal therapy for 213 sextants in 38 patients by two experienced periodontist examiners.

RESULTS

PSR scores of 4 identified untreated sextants with periodontal access surgery needs significantly better than PSR scores of 3 (odds ratio = 27.8; P <0.001) in multilevel, mixed-effects, logistic regression modeling analysis. However, only 37.6% of sextants with both pretreatment PSR scores of 4 and a pretreatment periodontal access surgery need continued to have surgical access needs after completion of non-surgical periodontal therapy. A higher percentage of sextants with PSR scores of 4 or 3 revealed periodontal access surgical needs when Class II or III furcation involvements and/or Grade II or III tooth mobility were also detected in the sextant than when these parameters were not detected.

CONCLUSIONS

Pretreatment PSR index scores of 4 were a strong indicator of periodontal access surgery needs in untreated dentition sextants but markedly overestimated surgical access needs remaining after completion of non-surgical periodontal therapy. These findings raise questions about the usefulness of pretreatment PSR evaluations for estimating potential periodontal access surgery needs in patients to be initially treated with non-surgical periodontal therapy.

Reliability of partial-mouth recording systems to determine periodontal status: a pilot study in an adult Portuguese population

BACKGROUND

The efficacy of various partial-mouth recording (PMR) systems is analyzed in the evaluation of periodontal status, using index teeth and different combinations of quadrants.

METHODS

The study group was formed of 108 adults aged 25 to 65 years old. A full-mouth examination (FME) was performed in all participants to determine the periodontal probing depth (PD) and clinical attachment level (CAL) at six sites per tooth. The results of PMR using the Ramfjord teeth, the Community Periodontal Index of Treatment Needs teeth, and the four quadrants individually and combined in pairs were compared to the results obtained with FME.

RESULTS

Concordance with FME in terms of the prevalence of patients with PD ≥4 mm, CAL ≥2 mm, and CAL ≥4 mm was lowest with examination of single quadrants and highest with combinations that included one superior and one inferior quadrant.

CONCLUSIONS

PMR systems, particularly with combinations of a superior plus an inferior quadrant, could be useful to evaluate periodontal status based on PD and CAL. This tool could be useful for epidemiologic surveys on periodontal status.

Periodontal disease progression and glycaemic control among Gullah African Americans with type-2 diabetes

AIM

To evaluate associations between glycaemic control and periodontitis progression among Gullah African Americans with type-2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

From an ongoing clinical trial among T2DM Gullah, we extracted a cohort previously in a cross-sectional study (N=88). Time from baseline (previous study) to follow-up (trial enrollment, before treatment interventions) ranged 1.93-4.08 years [mean=2.99, standard deviation (SD)=0.36]. We evaluated tooth site-level periodontitis progression [clinical attachment loss (CAL) worsening of > or =2 mm, periodontal probing depth (PPD) increases of > or =2 mm and bleeding on probing (BOP) from none to present] by glycaemic control status (well-controlled=HbA(1c)<7%, poorly-controlled=HbA(1c)> or =7%) using multivariable generalized estimating equations logistic regression, nesting tooth sites/person.

RESULTS

Poorly-controlled T2DM (68.18%) was more prevalent than well-controlled T2DM (31.82%). Proportions of tooth sites/person with CAL progression between baseline and follow-up ranged 0.00-0.59 (mean=0.12, SD=0.12), while PPD and BOP progression ranged 0.00-0.44 (mean=0.09, SD=0.11) and 0.00-0.96 (mean=0.24, SD=0.18), respectively. Site-level PPD at baseline was a significant effect modifier of associations between poorly-controlled T2DM and site-level CAL and PPD progression [adjusted odds ratios (OR) according to poorly-controlled T2DM among PPD at baseline=3, 5 and 7 mm, respectively: CAL progression=1.93, 2.64, and 3.62, PPD progression=1.98, 2.76, and 3.84; p<0.05 for all]. Odds of site-level BOP progression were increased (OR=1.24) for poorly-controlled T2DM, yet the results were not significant (p=0.32).

CONCLUSIONS

These findings from a distinct, homogenous population further support the clinical relevance of identifying patients with poor glycaemic control and periodontitis, particularly among those with disparities for both diseases.

Methods for the statistical analysis of binary data in split-mouth designs with baseline measurements

Many split-mouth trials are characterized by the pairing of site-specific outcome and baseline data within each segment of a subject's mouth. However when the response variable of interest is binary, methods of statistical analysis for this design are not well developed. In this paper we present several analytic approaches that may be taken to the resulting data, showing how the efficiency of statistical inferences can be improved by appropriately incorporating the baseline information. The advantages and disadvantages of the different approaches are discussed in the context of an example from the published literature. The results from a limited simulation study are also presented.

Case definitions for use in population-based surveillance of periodontitis

Many definitions of periodontitis have been used in the literature for population-based studies, but there is no accepted standard. In early epidemiologic studies, the two major periodontal diseases, gingivitis and periodontitis, were combined and considered to be a continuum. National United States surveys were conducted in 1960 to 1962, 1971 to 1974, 1981, 1985 to 1986, 1988 to 1994, and 1999 to 2000. The case definitions and protocols used in the six national surveys reflect a continuing evolution and improvement over time. Generally, the clinical diagnosis of periodontitis is based on measures of probing depth (PD), clinical attachment level (CAL), the radiographic pattern and extent of alveolar bone loss, gingival inflammation measured as bleeding on probing, or a combination of these measures. Several other patient characteristics are considered, and several factors, such as age, can affect measurements of PD and CAL. Accuracy and reproducibility of measurements of PD and CAL are important because case definitions for periodontitis are based largely on either or both measurements, and relatively small changes in these values can result in large changes in disease prevalence. The classification currently accepted by the American Academy of Periodontology (AAP) was devised by the 1999 International Workshop for a Classification of Periodontal Diseases and Conditions. However, in 2003 the Centers for Disease Control and Prevention and the AAP appointed a working group to develop further standardized clinical case definitions for population-based studies of periodontitis. This classification defines severe periodontitis and moderate periodontitis in terms of PD and CAL to enhance case definitions and further demonstrates the importance of thresholds of PD and CAL and the number of affected sites when determining prevalence.

Validity and reliability of partial examination to assess severe periodontitis

OBJECTIVES

To compare the extent and severity index (ESI) with a gold standard represented by actual readings of loss of attachment on six sites around all teeth present (excluding third molars).

METHODS

Five standardized dentists (kappa=0.6) examined 712 subjects > or =20 years of age at a dental school (1993-1995). Sensitivity, specificity, positive and negative predictive values, and true and apparent prevalence were established.

RESULTS

True severe periodontitis prevalence was 95.8%. ESI underestimated the severity (0.1 mm), extent (4%), and prevalence (16%) of periodontitis. The severity, as established by ESI, coincided 23.4% with the gold standard. ESI failed to identify 16.7% of subjects with severe periodontal disease, but specificity and positive predictive value were very high.

CONCLUSIONS

The underestimation of severe periodontitis through ESI may lead to inadequate recommendations for further treatment. Accurately identifying subjects with severe periodontitis requires a full-mouth examination. Because the ESI relies on measurements taken on only 28 periodontal sites to estimate the periodontitis status of the entire mouth, the validity and reliability of ESI may be modified by the prevalence of severe periodontal disease and the distribution of disease according to age and operational definitions.

Patient-based assessments of clinical periodontal conditions in relation to alveolar bone loss

BACKGROUND

Limited subject-based information exists on the relationship between clinical and radiographic periodontal data.

AIMS

To use subject-based data to assess the extent of concurrence between clinical and radiographic information, and to study what clinical information best predicts alveolar bone loss (ABL).

MATERIAL AND METHODS

Subject-based data on smoking habits, bleeding on probing, plaque scores, pocket probing depth (PD), and evidence of alveolar BL were obtained, and functional periodontal pentagon risk diagrams (PPRDs) were studied from 168 consecutive subjects attending a medical clinic.

RESULTS

The mean age of the subjects was 62.7 years (SD+/-9.0). The average number of teeth was 21.3 (SD+/-8.0) with on average 5.6 molars remaining (SD+/- 3.9). In this subject cohort, 33.1% had never smoked, 44.2% had quit smoking, and 22.7% were currently smokers. Mean plaque and bleeding scores were high or 60.2% (SD+/-24.0) and 53.1% (SD+/-23.6), respectively. PDs >or=6.0 mm were found in 55.9% of the subjects. Binary logistic regression analysis demonstrated that tooth loss and proportional plaque scores were the predominant factors included in the equations associated with ABL. Wald coefficients varied between 3.99 and 9.15, and with p-values between 0.05 and 0.01. When included, the PPRD score became the exclusive factor at several cut-off levels (Wald's coefficients between 19.8 and 15.6, p<0.001). Consequently, the best receiver operator curve was identified for the PPRD at the >40% cut-off ABL level (area under the curve: 0.81; 95% CI: 0.74-0.89; p<0.001).

CONCLUSIONS

The number of teeth lost and the proportion of plaque scores provided significant predictive factors for ABL. The functional PPRD demonstrated an exclusive and highly predictable association with ABL. Subject-based proportional data for PDs >4.0 mm provided poor substitute measures for the extent of ABL.

Partial-Mouth Assessment of Periodontal Disease in an Adult Population of the United States

BACKGROUND

It has been previously demonstrated, using periodontal data from an untreated population, that half-mouth assessment of six sites/tooth provides an appropriate alternative to whole-mouth assessment of periodontal disease status. Since periodontal destruction exhibits left-right symmetry, it was hypothesized that this would be equally applicable to a population with access to routine dental care.

METHODS

Adult subjects (N = 92) with a range of disease levels participated in the study. Probing depths (PDs) and recession (REC) were measured directly on six sites/tooth, on all teeth (excluding third molars), and clinical attachment levels (CALs) were derived. Partial-mouth assessments, i.e., assessment of limited sites and/or teeth, were compared with whole-mouth assessment as follows. Intraclass correlation coefficients (ICCs) were calculated for mean PD, CAL, and REC, and for percentage of sites with disease above a specified threshold, to determine the agreement between the whole- and partial-mouth assessment. The sensitivity of partial-mouth assessment of disease prevalence also was determined.

RESULTS

For assessment of six sites per tooth in one upper and one lower quadrant, ICCs were consistently >0.80. Assessment of two sites per tooth or only Ramfjord teeth generally underestimated disease extent and severity, and prevalence, compared to half-mouth assessment.

CONCLUSIONS

These results support the use of a half-mouth examination of six sites/tooth, to conserve time, limit cost, and reduce patient and examiner fatigue, while providing maximal clinical information. Assessment of only two sites per tooth or the Ramfjord teeth was not suitable for evaluation of either disease extent and severity or prevalence.

The Applicability of Half-Mouth Examination to Periodontal Disease Assessment in Untreated Adult Populations

BACKGROUND

Data from whole-mouth examinations are the gold standard for accurate assessment of periodontal disease. Since periodontal destruction exhibits left-right symmetry, however, it is hypothesized that a half-mouth exam provides an appropriate alternative to whole-mouth assessment, with considerable advantage over a more limited partial-mouth assessment of index teeth.

METHODS

Data from 2 untreated populations were utilized in the analyses. Half-mouth (random diagonal quadrants) and Ramfjord teeth assessment was compared with whole-mouth assessment as follows. Intraclass correlation coefficients (ICCs) were calculated for mean plaque index (PI), gingival index (GI), probing depth (PD), and clinical attachment level (CAL) and for percentage of sites with PD > or = 4, 5, or 6 mm; CAL > or = 3, 4, 5, or 6 mm; and recession > or = 3 mm to determine the agreement between the whole- and partial-mouth assessment. Disease prevalence was also determined for both whole- and partial-mouth assessments.

RESULTS

For mean PI, GI, PD, and CAL, both half-mouth and Ramfjord teeth assessment provided an acceptable alternative to whole-mouth assessment (ICCs > 0.92). For percentage of sites above a specified threshold, ICCs were generally greater than 0.90 in all age cohorts for half-mouth assessment, but consistently lower for Ramfjord teeth assessment. Ramfjord teeth assessment also considerably underestimated disease prevalence compared with half-mouth assessment.

CONCLUSIONS

These results support the use of a half-mouth examination procedure, to conserve time, limit cost, and reduce patient and examiner fatigue while providing maximal clinical information. Ramfjord teeth assessment was not as suitable for evaluation of either disease extent or prevalence.

Subgingival microbiota of indigenous Indians of Central America

OBJECTIVE

To define the subgingival microbial profiles of adult subjects from a previously identified rural community of indigenous Indians in Guatemala, Central America.

MATERIALS AND METHODS

A full-mouth periodontal examination was performed in 114 adult subjects from 45 families. Plaque samples were collected from both deep and shallow periodontal pockets and checkerboard DNA-DNA hybridization was employed to identify 17 species previously associated with periodontitis or health.

RESULTS

Plaque deposits and gingivitis were universal and widespread, and periodontal pocketing > or =5 mm was highly prevalent (84% of subjects). Streptococcus sanguis, Actinomyces naeslundii genospecies 2 and Fusobacterium nucleatum were significantly more prevalent in shallow sites. At the subject level, Actinomyces naeslundii and Peptostreptococcus micros were significantly more prevalent in periodontally-healthy subjects. Actinobacillus actinomycetemcomitans was not detected in any sample.

CONCLUSION

There was no association between periodontal disease status and presence of suspected periodontal pathogens. These latter results conflict somewhat with those from treated populations. However, in this population where extensive plaque deposits and gingivitis are universal, the presence of putative pathogens may be more reflective of the local environment.

Microflora in adult periodontitis

The subgingival microflora of adult periodontitis was studied in 8 adults (36-47 years) and compared with that of 10 periodontally healthy individuals (36-43 years). A total of 64 periodontal lesions were examined, and classified according to the attachment level in three categories: attachment loss > 6 mm, attachment loss 4-6 mm and attachment loss < 4 mm. Also for comparative purposes 20 gingival sulci were evaluated. Samples were taken using three standardized paper points and were incubated anaerobically in selective and non-selective media. The results showed a statistically significant association of Capnocytophaga gingivalis and Capnocytophaga sputigena with moderate periodontal lesions, while Haemophilus segnis has been correlated to severe periodontal lesions. We concluded that C. gingivalis, C. sputigena and H. segnis might be potentially conductive to periodontal deterioration in adult periodontitis.

Variance component modeling of attachment level measurements

The purpose of this study was to investigate the influence of within subject and within tooth variability of attachment-level measurements on hypothesis testing. Full-mouth attachment-level measurements were obtained at 4 sites per tooth in early onset periodontitis subjects (both localized N = 89 and generalized N = 139) and adult periodontitis subjects (N = 309). Variance component models utilizing iterative generalized least squares were employed to estimate the % of variance distributed at the level of the site, tooth and subject in the 3 subject populations. The data indicate that a significant % of the variance is distributed within the tooth and the subject. Ignoring the variance attributable to teeth or subjects can result in inappropriately low type I error rates for hypothesis testing. Thus, both the subjects and the tooth must be considered in the modeling of attachment level measurements. Also in studies in which a limited number of samples are taken, data analysis would be simplified if these samples were taken from different teeth.

Toward strategies for the analysis of periodontal disease clinical trials

We consider design, analysis and regulatory issues relating to clinical trials in periodontal disease and identify complications commonly associated with such studies. Alternative statistical procedures that can be used for the analyses of data from periodontal research are reviewed and a case study of the analysis of a Phase II periodontal disease clinical trial is provided to illustrate the use of one of these procedures.

Multicenter evaluation of tetracycline fiber therapy: I. Experimental design, methods, and baseline data

The study design and baseline characteristics of a multicenter trial to test the effectiveness and safety of locally delivered tetracycline for treatment of adult periodontitis are described. Local delivery was provided by 0.5 mm diameter ethylene vinyl acetate copolymer fibers loaded 25% with tetracycline hydrochloride which were placed into periodontal pockets and maintained by an adhesive for 10 (+/- 2) days. A total of 113 subjects (56 male and 57 female; mean age 49.3 yr) at five centers participated in the study. Subjects were selected who had 4 nonadjacent teeth with 6-10 mm pockets that bled on probing. The selected sites in each subject were randomly assigned to 4 test groups: tetracycline fiber, control fiber, scaling with root planing, or untreated. A balanced experimental design was thereby established in which each subject contributed equally by providing 4 clinically comparable sites for evaluation. To provide a more specific model for testing periodontitis therapy, gingivitis was treated prior to the initiation of the study by prophylaxis with supragingival calculus removal and home care instruction. Clinical response variables measured were pocket depth reduction, attachment level gain and bleeding on controlled-force probing measured at baseline, 30 d, and 60 d. Levels of 6 bacterial species selected as probable periodontal pathogens were measured by DNA probe analysis of plaque samples. The design of this study provided several unique analytical opportunities. Controls included a comparison with conventional treatment, analysis of vehicle effects, and effects at untreated sites. Comparison of the test group with controls permitted evaluation of the principal variables that could effect interpretation of results.(ABSTRACT TRUNCATED AT 250 WORDS)

Periodontal disease activity: a critical assessment

Review of investigations using longitudinal probing and radiographic assessments indicate that the prevalence, magnitude, rate, and temporal patterns of periodontal destruction as well as the ability of clinical and laboratory tests to detect and predict loss of clinical attachment need further investigation. These unresolved issues are discussed and their impact on the practice of periodontics is examined.

Statistical models for data from periodontal research

Many factors have been hypothesised either to characterise groups and individuals at risk for periodontal disease or to be markers of periodontal breakdown. In order to identify these as associated either with disease status or progression, a statistical association between the factor and a measure of disease will have to be demonstrated. The statistical modelling of data arising from periodontal research presents special problems. These include the large number of measurements made in each subject, the large magnitude of measurement error compared to the changes in attachment level, the analysis of longitudinal studies, the lack of a measure of instantaneous rate of attachment loss and controversies over the nature of the progression of the disease. We consider statistical methods currently available in the light of these difficulties and identify areas in which further research is necessary.

Evaluation of gingival bleeding following 4 types of periodontal therapy

This study evaluated the effects of 4 types of periodontal therapy (coronal scaling (CS), root planning (RP), modified Widman surgery (MW), and flap with osseous resectional surgery (FO] and subsequent maintenance care upon bleeding on probing (BOP). 75 individuals completed split mouth therapy and 2 years of maintenance followup. Data were obtained by 1 calibrated examiner prior to the initiation of therapy, following the hygienic phase and surgical phase of active therapy and yearly during maintenance care. All types of therapy reduced the prevalence of BOP. At the end of 2 years of maintenance therapy, regions greater than 5 mm treated by CS demonstrated a significantly (p less than 0.05) greater prevalence of BOP sites than regions treated by the other modalities. Generally, sites associated with deeper probing depths exhibited a greater tendency to bleed and sites with associated plaque accumulation bled more frequently. RP resulted in a significantly (p less than 0.05) higher % of bleeding sites that stopped following active therapy than did CS. Throughout the study, BOP was extremely dynamic, with 15-88% of sites converting to a new status between any 2 examination periods. This dynamic nature may explain the inability of previous investigations to establish BOP as a reliable predictor of periodontal breakdown.

Gingival resistance to probing forces. II. The effect of inflammation and pressure on probe displacement in beagle dog gingivitis

This study was undertaken to determine the effect of gingival inflammation and probing pressure on probe tip placement in relation to the base of the gingival crevice and the most coronal connective tissue attachment fibers. Nine young male beagle dogs were divided into three groups as determined by clinical status of the gingiva following implementation of a protocol designed to produce gingival health and disease. An electromechanical device was used to advance 0.6 mm diameter probes into the facial gingival crevices of selected teeth and to obtain force-displacement curves. The instrument stopped the probe at pressure of either 80, 160, 320, 640, 1280, or 2560 kPa which were randomly allocated to 12 test teeth in each dog. After the probe came to rest, it was attached to the tooth. When all 12 probes were attached, the animal was sacrificed. Blocks consisting of gingiva, probe, and tooth were processed to obtain two buccolingual sections, one containing the probe and the other immediately adjacent to it. Clinical and histometric measurements were performed and the data evaluated. Although three groups of animals were discernable by clinical criteria, only two groups, health and disease, could be formulated based on the degree of histologic inflammation. The histologic grouping was used in data analysis. Histometric distances from the cemento-enamel junction to the base of the crevice (cJ), to most coronal connective tissue attachment (cC) and to the probe tip (cP) all increased with change from health to disease. However, changes in health/disease did not influence difference between distances (cP-cJ,cP-cC).(ABSTRACT TRUNCATED AT 250 WORDS)

The detection of in vitro produced periodontal bone lesions by conventional radiography and photographic subtraction radiography using observers and quantitative digital subtraction radiography

Changes in the periodontium produced by removal of bone cylinders at one interdental site of a dry human mandible, were recorded radiographically. These artificial lesions had diameters of 0.3 mm increasing to 1.4 mm in steps of 0.1 mm. Radiographs were obtained using 3 different X-ray tube potentials and 3 different amounts of radiation. These 9 exposure variables resulted in 9 series of radiographs from the artificial lesions. Observers were asked to determine the presence or absence of these periodontal bone lesions on conventional radiographs and on photographically subtracted images. The images were also evaluated by a quantitative digital subtraction technique. This study showed that the smallest periodontal bone changes were detected with the quantitative digital subtraction technique compared to the other methods using observers. On photographically subtracted images, smaller bone changes were detected by the observers than on conventional radiographs. Only the detection threshold of the quantitative digital subtraction technique was influenced by the 2 exposure factors: kVp and mAs.

Crestal alveolar bone change in patients with periodontitis as observed by subtraction radiography: an overview

Subtraction radiography is a highly sensitive and useful technique for detecting crestal alveolar bone changes in patients. Utilizing this technique, researchers have demonstrated that 9% of crestal sites lose bone over a six-month period in untreated subjects with periodontitis. On the order of 10-13% of crestal sites were found to lose bone three months post-periodontal therapy which included surgery. Non-surgical therapy resulted in 0.5-2% of crestal sites with bone loss. Subtraction requires radiographs which have closely approximating projection geometry. Presently available technology for taking standardized radiographs based on an occlusal stent system is adequate for obtaining interpretable subtraction images.

Accuracy of repeated single versus averages of repeated duplicates of probing depth measurements

The present study aims to determine to which extent averages or deepest recordings of repeated duplicates of probing depth measurements may increase the accuracy as compared to repeated single measurements. In total, 1247 sites were recorded in 8 patients with advanced periodontitis. The patients had received initial treatment. Each site was probed 4 times with time intervals of 100 min. The standard deviation of differences between repeated single measurements of 0.97 mm decreased with a factor square root of 2 to 0.69 mm for differences between averages of repeated duplicates of measurements. Differences between the averages and the deepest recordings of repeated duplicates of measurements showed a non-Gaussian distribution. This implies that the type-I error can not be computed on the basis of the standard deviation of the error with the use of parametric statistical analysis. The best estimate for the type-I error is the observed frequency of differences. The type-I error for differences of 3 mm or more between repeated single measurements decreased from 1.5% to 0.9% and 0.2%, when deepest recordings and averages of repeated duplicates of measurements, respectively, were compared.

A re-examination of within-mouth correlations of attachment level and of change in attachment level

Using a data set from the Forsyth Dental Center consisting of repeated measurements of periodontal attachment level on 22 patients over 1 year, we performed correlation analyses at 4 time points (baseline, 1 month, 6 months and 9 months) for 3 units of measurement (sites, teeth and quadrants). Values of the intraclass correlation coefficient were obtained for the cross-sectional measurements and for changes from baseline. The values were positive and often of appreciable magnitude, indicating that measurements of attachment level and of change in attachment level within the same mouth are positively correlated. Taking sites rather than patients as the units of statistical analysis in comparative clinical trials in periodontology will therefore tend to produce underestimated standard errors and overstated statistical significance.

Short-term effect of Keyes' approach to periodontal therapy compared with modified Widman flap surgery

Keyes' method of non-surgical therapy was compared with modified Widman flap surgery in 9 patients with symmetrical periodontal disease. Following an initial oral hygiene programme, baseline measurements were recorded and paired contralateral areas were subjected randomly to the 2 techniques. 42 teeth receiving surgery were compared with 40 treated by Keyes' method. 6 sites per tooth were scored immediately prior to therapy and 3 months later, using a constant force probe with onlays. Consistent data were recorded for the 6 separate sites, which showed no baseline difference between treatments, slightly greater recession with surgery at 3 months, but no difference between treatments in probing depth and attachment levels. Mean data for individual patients showed similar consistency. Probing depth in deep sites was reduced slightly more with surgery, and there were no differences in bleeding on probing at 3 months. Both techniques gave marked improvements in health. Surprisingly, only 2 subjects preferred Keyes' technique of mechanical therapy, 6 preferred surgery, and 1 had no preference.

Within-mouth correlations and reliabilities for probing depth and attachment level

Replicate measurements of probing depth and attachment level were made by three examiners on the six Ramfjord teeth of 34 patients. Within-mouth correlations were high for single measurements, and yet higher for means across replicate measurements. Inter- and intra-examiner variability were both found to be low relative to between-patient variability. Conclusions are that the low within-mouth correlations reported by others may be the result of poor reliability, and that it is inappropriate to take the individual site as the unit of statistical analysis in clinical studies of periodontitis.

The efficiency of half-mouth examinations in estimating the prevalence of periodontal disease

Several studies, including the NIDR 1985 national survey of working adults, have used periodontal examinations of only two quadrants of the mouth to estimate the prevalence of periodontal conditions. To investigate the efficiency of half-mouth periodontal examinations, I compared the results from the examination of all teeth in a sample of 477 dentate elderly people with scores that would have been obtained if randomly selected pairs of quadrants had been examined instead. In this elderly dentate population, relatively little information would have been lost if diagonal half-mouth or same-side half-mouth scores instead of whole-mouth scores had been used to estimate the number or proportion of teeth with periodontal conditions. However, the proportion of people with the less prevalent conditions, i.e., deep pocketing and mobility, was underestimated slightly. Slightly less efficiency was also noted for the less prevalent conditions. These findings suggest that half-mouth recording may be useful for prevalence surveys, but cannot be recommended for incidence surveys or clinical trials, where incremental changes may be small.

Analysis of data from clinical studies of localized juvenile periodontitis

Data from 27 subjects with localized juvenile periodontitis were used to compute estimates of the intraclass correlation coefficient for initial periodontal pocket depth measurements and total subgingival Actinobacillus actinomycetemcomitans counts, and for changes from pre- to post-treatment in periodontal pocket depth, probing attachment level and Actinobacillus actinomycetemcomitans counts. The estimates for the clinical parameters were considerably higher than those found in a similar study of adult periodontitis. On the average, the estimates for the intraclass correlation coefficients for Actinobacillus actinomycetemcomitans counts did not differ markedly from the corresponding estimates for the clinical parameters. Although the results of this study indicate that the major component of variability in parameters commonly used in studies of periodontal disease can be attributed to site-specific factors, sites within subjects cannot be considered statistically independent. For the analysis of data arising from studies of periodontal disease, it is recommended that statistical techniques, like the nested mixed effects analysis of variance model be employed, which account for this dependence. These techniques will allow meaningful biological questions concerning site-specific phenomenon to be answered. However, changes in clinical and microbiological parameters, when therapeutic measures are employed on localized juvenile periodontitis patients, are often dramatic enough to allow informal data presentation.

Considerations in the statistical analysis of clinical trials in periodontitis

Adult periodontitis has been described as a chronic infectious process exhibiting sporadic, acute exacerbations which cause quantal, localized losses of dental attachment. Many analytic problems of periodontal trials are similar to those of other chronic diseases. However, the episodic, localized, infrequent, and relatively unpredictable behavior of exacerbations, coupled with measurement error difficulties, cause some specific problems. Considerable controversy exists as to the proper selection and treatment of multiple site data from the same patient for group comparisons for epidemiologic or therapeutic evaluative purposes. This paper comments, with varying degrees of emphasis, on several issues pertinent to the analysis of periodontal trials. Considerable attention is given to the ways in which measurement variability may distort analytic results. Statistical treatments of multiple site data for descriptive summaries are distinguished from treatments for formal statistical inference to validate therapeutic effects. Evidence suggesting that sites behave independently is contested. For inferential analyses directed at therapeutic or preventive effects, analytic models based on site independence are deemed unsatisfactory. Methods of summarization that may yield more powerful analyses than all-site mean scores, while retaining appropriate treatment of inter-site associations, are suggested. Brief comments and opinions on an assortment of other issues in clinical trial analysis are preferred.

Clinical measurements of periodontitis

Clinical measurement of periodontitis has historically focused on the concept of periodontitis as a slow, continuous process which has emphasized measurements of the static condition of periodontal pockets. Observations based on longitudinal measurement of attachment loss in untreated subjects have indicated that periodontal destruction occurs in discrete episodes of short duration. Based on these studies, it has been suggested that chronic periodontal disease proceeds through a series of random episodic attacks. Periodontal sites are considered as existing in 2 states, either disease active or inactive. During periods of disease activity, sites increase in their probable depth, whereas during the inactive state, no significant change in probing depth can be detected. The detection of changes at periodontal sites from time series data has been addressed by 3 analytical procedures: regression, running medians, and tolerance. The standard deviation of differences between replicate measurements of 48,064 sites for 56 subjects was 0.7727 mm. From this estimate, the computed standard deviation for a single measurement was 0.5464 mm and for the mean of 2 measurements was 0.386 mm. The expected error rates of each method have been estimated by computer simulation. The type-I error for the regression (p = 0.028), running median (p = 0.000025), and tolerance (p = 0.00012) methods were all sufficiently low to consider it unlikely that reported observations could be accounted for by methodologic error. The estimated type-II error for the regression (p = 0.446), running median (p = 0.152), and tolerance (p = 0.068) methods suggests that a substantial fraction of disease active sites was not detected by these methods. Several data set properties have been investigated. Intraclass correlation coefficients were computed from attachment level changes on 8,130 sites in 105 patients. By this analysis, 7% of the variation was associated with the subject and 93.3% with the individual sites, indicating that attachment level changes at periodontal sites exhibit a high degree of statistical independence. Autocorrelation within sequential attachment level measurements was computed and found low (0.081 in 22 subjects and 0.099 in 45 subjects), indicating that computed variance is not systematically underestimated due to autocorrelation within the data set. Clinical measurements which have failed to exhibit association with episodic attachment loss include gingival redness, bleeding on probing, suppuration, supragingival plaque, and darkfield microscopic bacterial counts.(ABSTRACT TRUNCATED AT 400 WORDS)

On the choice of computational unit in statistical analysis

It is stated that in trials where experimental units on different levels (sites, patients, etc.) are employed, the highest level unit should be used as computational unit when computing standard errors and in statistical inference. Using a lower level unit will underestimate the standard error and the level of significance (P-value). A numerical illustration is presented.