Oral hygiene reinforcement in the simplified periodontal treatment of 1 hour

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1 J Clin Periodontol 2014; 41: doi: /jcpe Oral hygiene reinforcement in the simplified periodontal treatment of 1 hour Danae A. Apatzidou, Penelope Zygogianni, Dimitra Sakellari and Antonis Konstantinidis Department of Preventive Dentistry, Periodontology and Implant Biology, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece Apatzidou DA, Zygogianni P, Sakellari D, Konstantinidis A. Oral hygiene reinforcement in the simplified periodontal treatment of 1-hour. J Clin Periodontol 2014; 41: doi: /jcpe Abstract Aim: To compare the clinical and microbiological outcome of the 1-h ultrasonic debridement of chronic periodontitis patients (CPP) with and without frequent sessions of oral hygiene reinforcement. Methods: Clinical measurements and subgingival plaque were collected from 44 CPP at baseline, 3- and 6-months. The control group received a single session of 1-h full-mouth ultrasonic debridement, while oral hygiene instructions (OHI) were reiterated over four visits. In the test group, OHI were limited in the 1-h treatment session. At 3-months, both groups received additional debridement and OHI. The Checkerboard DNA-DNA hybridization technique quantified Porphyromonas gingivalis, Tannerella forsythia and Treponema denticola in plaque. Results: At three months, smaller reductions in plaque and bleeding indices, and in P. gingivalis numbers were noted in the test group, while these differences disappeared at six months. After the 3-month re-treatment visit, the test group presented with a greater probing pocket depth (PPD) reduction. Plaque negatively affected PPD in a similar manner after both treatment approaches. Conclusions: Lack of oral hygiene reinforcement in the 1-h full-mouth debridement resulted in higher plaque and bleeding scores and numbers of P. gingivalis at three months; professional removal of dental biofilm every three months is beneficial in subjects with compromised plaque control. Key words: oral hygiene reinforcement; periodontal treatment; plaque control; ultrasonic debridement Accepted for publication 17 November 2013 Conflict of interest and source of funding statement The authors declare that they have no conflict of interests. No external funding, apart from the support of the authors Institution, was available for this study. In recent years, non-surgical periodontal treatment has been criticized for its time length which is comparable to, or even exceeds that required for a major medical operation (Kinane 2005). A review of the literature regarding the time frame of non-surgical periodontal treatment demonstrates a wide range across studies in the time required for fullmouth instrumentation as well as in the time intervals between treatment sessions. In general, we allow 1 h to scale and root plane each quadrant using hand and power driven instruments under local anaesthesia. This treatment approach can be usually performed over four sessions at weekly or bi-weekly intervals, the socalled traditional non-surgical periodontal treatment. It has been shown that full-mouth scaling and root planing (SRP) can be completed in considerably smaller time intervals, that is, over two consecutive sessions within 24 h with and without the extensive use of antiseptics (Quirynen et al. 2000) and more recently on a single visit in the sameday that is less than 12 h with no adjunctive use of antiseptics (Apatzidou & Kinane 2004). Time length of full-mouth treatment can be dramatically reduced to less than 2½ hona single visit, when ultrasonics are exclusively used for the debridement 149

2 150 Apatzidou et al. of the four quadrants under local anaesthesia, if requested by the patient (Koshy et al. 2005). More impressively, Wennstr om et al. (2005) reduced the time frame of full-mouth periodontal therapy in moderately advanced CPP into 1 h using ultrasonics solely under local anaesthesia, when necessary. Although the 1-h full-mouth ultrasonic debridement resulted in a smaller percentage of closed pockets (PPD < 5 mm), compared with the traditional treatment of SRP per quadrant on a weekly basis, the efficiency of the initial treatment phase (baseline to 3 months), defined as the time spent for instrumentation divided by the number of closed pockets, was significantly higher for the full-mouth ultrasonic debridement (3.3 versus 8.8 min. per closed pocket) (Wennstr om et al. 2005). Of great importance was the fact that oral hygiene instructions (OHI) were given on four occasions throughout the study in a similar manner for both treatment groups. The authors suggested that this simplified compact treatment of 1-h in combination with careful oral hygiene measures is a justifiable initial treatment approach of chronic periodontitis. On this basis, this study aimed to compare the clinical and microbiological outcome of the simplified 1-h full-mouth ultrasonic debridement of CPP with and without frequent follow-up sessions for oral hygiene reinforcement. Materials and Methods This study was designed as a 6-month prospective, randomized controlled clinical trial (Altman et al. 2001) and was conducted at the Postgraduate Clinic of the Department of Preventive Dentistry, Periodontology and Implant Biology, Dental School, Aristotle University of Thessaloniki, Greece (AUTh). The study was approved by the Ethical Committee of the School, and all participants signed an informed consent. The flowchart of the study is presented in Fig. 1. Study population Forty-four systemically healthy CPP, all of Caucasian origin were recruited from new referrals to the Department Control group (n = 23) Baseline - Oral hygiene instructions - 1-hr full-mouth ultrasonic debridement Exclusion of 1 subject due to antibiotics for implant therapy 2nd week (n = 23) 4th week (n = 22) 6th week (n = 22) 3-month reassessment (R1) (n = 22) - Supragingival plaque control - Subgingival debridement of 5 mm sites 6-month reassessment (R2) (n = 22) Fig 1. Flow chart of the study of Periodontology, AUTh. Table 1 depicts the demographic details of the participants. Recruitment was made on the basis that each subject had at least two non-adjacent sites per quadrant with PPD 5 mm, clinical attachment levels (CAL) 5 mm and Table 1. Screening examination (n = 49) Consent form Stratification for smoking Random allocation (n = 47) Exclusion of 2 subjects (No of teeth <18) Exclusion of 2 subjects (Failed to attend twice) Test group (n = 22) Baseline - Oral hygiene instructions - 1-hr full-mouth ultrasonic debridement 3-month reassessment (R1) (n = 22) - Supragingival plaque control - Subgingival debridement of 5 mm sites 6-month reassessment (R2) (n = 22) radiographic evidence of bone loss, and bleeding on probing (BOP). Exclusion criteria included less than 18 teeth excluding third molars, periodontal treatment/scaling within 12 months prior to baseline assessment, history of systemic disease, Demographic details and baseline data of the participants Gender Age No of teeth* Smokers Pack year Control group 15F/7M 57.4 (11.4) 22.5 (3.0) (6418.7) Test group 14F/8M 54.6 (10.4) 23.0 (2.6) (5538.2) Mean (SD). All participants were of Caucasian origin. F, females; M, males. *Excluding third molars; cigarette smoking status was self-reported and was quantified as pack year; packs of cigarettes smoked per day multiplied by the number of years as a smoker (National Cancer Institute, N.I.H.

3 Simplified periodontal treatment 151 compromised medical conditions requiring prophylactic antibiotic coverage, antibiotic therapy within the last three months or during the course of the study, pregnancy, lactation. Clinical recordings Full-mouth periodontal recordings included BOP; plaque index (PI) (presence or absence of plaque) (O Leary et al. 1972); PPD and CAL (distance between the cementoenamel junction of the tooth and the deepest aspect of the pocket) which were determined using a manual periodontal probe (Hu-Friedy XP- 23/QW; Hu-Friedy, Chicago, IL, USA) to the nearest millimetre at six sites per tooth and parallel to the long axis. Clinical interventions The screening visit included initial periodontal assessment, intra-oral radiographic examination and fulfilment of inclusion criteria. Extractions regarding hopeless teeth were performed before the collection of clinical data. In case of suitability a signed consent form was obtained from each subject who was subsequently allocated into one of the two treatment groups. One week later, baseline full-mouth periodontal measurements were recorded and subgingival plaque samples were collected from four pre-selected sites. Subsequently, 1-h single-visit full-mouth ultrasonic debridement was performed under local infiltration anaesthesia if required by the patient. Approximately two cartridges of local anaesthetic (1.8 ml of 2% lidocaine with 1:80,000 epinephrine; Lignospan special; Septodont, Saint-Maur-des-Fosses, France) were infiltrated in the buccal aspects of the upper and lower teeth. Instrumentation was performed using a piezoelectric ultrasonic device (EMS Piezon â EMS, Nyon, Switzerland) with A and P instruments (Swiss Instruments PM EMS) under water irrigation and was restricted to 1 h for both groups. The tips were examined after each session and were not used again if they had been worn out. Teeth were then polished using a rubber cup and moderately abrasive polishing paste containing fluoride (Proxyt RDA 36, medium; Ivoclar Vivadent, Liechtenstein). No antiseptics were used throughout the study period. The OHI included morning and night tooth brushing employing the modified Bass technique with a soft toothbrush (Waerhaug 1981), in addition to nightly inter-dental cleaning. At baseline, patients followed the demonstration of OHI and then applied the brushing technique onto their dentition using the customized oral hygiene aids (Tepe, Sweden) under the therapist s supervision, who made all necessary adjustments. Clinical assessments and collection of plaque samples were repeated at three and six months from baseline. During the initial phase of treatment (baseline to 3 months) OHI and reinforcement were carried out over four sessions at bi-weekly intervals for the control group in a similar manner as the standard non-surgical periodontal treatment, whereas on one occasion (baseline) for the test group. At three months full-mouth supragingival plaque deposits were removed and teeth were polished in both groups. The remaining pockets ( 5 mm, BOP+) received additional ultrasonic scaling with no time limitation. On this occasion, OHI and motivation were given to all participants in a standardised manner. Microbiological analysis Subgingival plaque samples were collected from one site per quadrant with the deepest PPD and not shallower than 5 mm, with no endodontic or furcation involvement. Supragingival plaque deposits were carefully removed using a curette, and then sites were isolated from saliva with cotton rolls and gently airdried in an apico-coronal direction. Subgingival plaque was collected from the most apical part of the pocket using a sterile curette. Samples were stored on ice in sterile micro-centrifuge tubes containing 100 ll of TE buffer (Tris-HCl 10 mm, EDTA 1 mm, ph = 7.5) and 100 ll alkali solution (0.5N NaOH) and finally stored at 20 C until required. The microbiological samples were assessed for P. gingivalis, T. forsythia and T. denticola using the checkerboard DNA DNA hybridization technique (Socransky et al. 1994). Bacterial species were quantified based on a reference curve, which allowed the conversion of the chemiluminescence signals to total bacterial counts (Total Lab TM v2005; Nonlinear Dynamics Ltd., Newcastle upon Tyne, UK). Sample size calculation The primary outcome variable was deemed to be differences in PPD between the two treatment approaches, while the inter-group differences in CAL, PI and BOP were considered as secondary variables. Previous power calculations based on PPD differences between the 1 h and the quadrant-wise treatment approach required 20 subjects in each group (Wennstr om et al. 2005), while more recently a metaanalysis by Eberhard et al. (2008) carried out a power analysis assessing differences in PPD between multiple-session and one-stage treatment protocols and based on these data 22 participants were required in each group (DPPD = 0.53 mm, common standard deviation = 0.6 mm, a error = 0.05, b error = 0.20). Randomization and concealment Patients were screened for eligibility by one examiner (PZ) and were enrolled one at a time on a continuous basis. Stratification was performed based on smoking status and within each of the two subgroups of current smokers and non-smokers, patients were randomly allocated into either treatment group using computer-generated lists. A trial contributor not otherwise clinically involved (DAA) performed the randomisation and announced the treatment modality of each participant to PZ using telephone communication in order to secure allocation concealment. The subjects were assessed clinically by a single calibrated examiner, who also provided treatment (PZ). Intra-examiner reproducibility was assessed by duplicate probing measurements on three subjects with advanced periodontitis; limits of agreement ranged from 0.08 to 0.24 for PPD and from 0.26 to 0.28 for CAL (Bland & Altman 1986). In this study, 100% of the differences between duplicate measurements were within the limits of agree-

4 152 Apatzidou et al. ment. In order to ensure unbiased data collection, the examiner had no access to previous recordings throughout the study. Plaque samples and clinical data were coded, so that the statistical and laboratory analyses were performed in a blind manner. Statistical analysis The patient was used as the experimental unit for analysis. The primary analysis was per protocol (Altman et al. 2001) and included all patients who were examined at baseline and also attended the final assessment (n = 44 subjects). Analysis of clinical data was based on full-mouth measurements excluding third molars. A further analysis was performed based on initial PPD, for moderately deep sites (5 6 mm) and deep sites ( 7 mm). The assumption of normality for scale variables was tested by the Shapiro Wilk test and was rejected. Comparisons over the three time points within each group were performed using the Wilcoxon signed-rank test and were adjusted with the Bonferroni test for Type-I error (each p-value was multiplied by three). At baseline the homogeneity between groups for all clinical and microbiological parameters was checked using the Mann Whitney U-test. Similarly, post-treatment comparisons between groups were conducted using the Mann Whitney U-test. This test was also used to compare the changes with treatment between the two groups (3- and 6- months from baseline; 3- to 6- months). Averaged bacterial scores from each subject were used for the microbiological analysis. A Linear Mixed Model with visit (1st level), site (2nd level), tooth (3rd level) and patient (4th level) as random factors and visit (baseline, 3 months, 6 months), treatment group (control, test) and PI (presence, absence) as fixed factors was used to estimate the effect of microbial plaque onto the log-transformed values of PPD (West et al. 2007). Statistical significance was set at p < 0.05 for hypothesis testing. Statistical analysis was carried out using SPSS statistical software (SPSS version 18.0; SPSS Inc., Chicago, IL, USA). Results No significant inter-group differences were found at baseline (p > 0.05). Clinical parameters The longitudinal analysis of data revealed significant improvements in all clinical parameters for both treatments at 3- and 6-months from baseline (p < 0.001) (Table 2). The control group demonstrated further improvements in PPD and percentage of 7 mm sites between 3- and 6- months (p < 0.05), while in this time interval, the test group exhibited marked improvements in all clinical indices except for PI. The inter-group comparisons revealed that the control group demonstrated significantly lower PI and BOP at 3-months (p < 0.05), together with a greater reduction in plaque and bleeding scores at 3-months from baseline compared with the test group (p < 0.01) (Table 2). When the changes in PPD were compared between the two treatments, a significantly greater PPD reduction was noted in the test group between 3- and 6-months (p < 0.01). No differences in the percentage of moderately deep (5 6 mm) and deep ( 7 mm) sites were found between groups post-treatment (p > 0.05) (Table 2). Clinical data were analysed based on initial PPD and the inter-group Table 2. Full-mouth clinical parameters (mean SD) N control group = 22 N test group = 22 BAS 3 months 6 months Change (BAS 3 months) Change (BAS 6 months) Change (3 6 months) PI (%) Control group Test group BOP (%) Control group Test group * PPD (mm) Control group *, Test group * CAL (mm) Control group Test group * Sites 5 mm (%) Control group * Test group * Sites 5 6 mm (%) Control group Test group * Sites 7 mm (%) Control group * Test group * Wilcoxon s signed-rank test: significant longitudinal changes were noted at 3- and 6-months from baseline within each group (p < 0.001); *p < 0.05 represents significant longitudinal changes between 3- and 6-months within each group; Mann Whitney U-test: p < 0.05, p < 0.01 represent significant differences between treatment groups. BAS, baseline; control group, 1-h debridement with regular checkups; test group, 1-h debridement with limited oral hygiene reinforcement; PI, plaque index; BOP, bleeding on probing; PPD, probing pocket depth; CAL, clinical attachment levels.

5 Simplified periodontal treatment 153 comparisons of moderately deep sites demonstrated a greater reduction in PI and BOP for the control group at 3-months from baseline (p < 0.05) (Table 3). In contrast, a greater decrease in PPD was found in the test group over the control group between 3- and 6-months (p < 0.01). The longitudinal analysis of data at moderately deep sites revealed significant post-treatment decreases in all clinical indices for both groups (p < 0.001) with the test group presenting a marked clinical improvement between 3- and 6-months (Table 3). The analysis of deep sites demonstrated a greater reduction in BOP for the control group over the test group at baseline to 3-months (p < 0.05), while this inter-group difference was reversed in favour of the test group between 3- and 6- months (p < 0.05) (Table 4). At deep sites, both groups demonstrated significant clinical improvements at 3- and 6-months from baseline (p < 0.001), while a further improvement between 3- and 6- months was noted for some of the clinical indices (p < 0.05). The multilevel analysis (LMM) revealed that PI had a negative effect on PPD in each group and each visit (p < 0.002); plaque presence in the control group resulted in no significant differences in mean PPD values between 3- and 6-months (p = 0.603); the two treatments resulted in similar PPD at each visit, in presence or absence of plaque (p > 0.276). These findings were derived from the pair-wise comparisons with Bonferroni adjustment, which were based on the statistically significant 3 way interaction depicted in Table 5. Table 3. Changes in clinical parameters (mean SD) for moderately deep pockets (5 6 mm) on a subject level BAS BAS 3 months BAS 6 months 3 6 months PI (%) Control group Test group BOP (%) Control group Test group * PPD (mm) Control group *, Test group * CAL (mm) Control group Test group * Wilcoxon s signed-rank test: significant longitudinal changes were noted at 3-and 6 months from baseline within each group (p < 0.001); *p < 0.05 represents significant longitudinal changes between 3- and 6 months within each group; Mann Whitney U-test: p < 0.05, p < 0.01 represent significant differences between treatment groups. BAS, baseline; control group, 1-h debridement with regular checkups; test group, 1-h debridement with limited oral hygiene reinforcement; PI, plaque index; BOP, bleeding on probing; PPD, probing pocket depth; CAL, clinical attachment levels. Table 4. Changes in clinical parameters (mean SD) for deep pockets ( 7 mm) on a subject level BAS BAS 3 months BAS 6 months 3 6 months PI (%) Control group Test group BOP (%) Control group Test group * PPD (mm) Control group * Test group * CAL (mm) Control group * Test group * Wilcoxon s signed-rank test: significant longitudinal changes were noted at 3-and 6 months from baseline within each group (p < 0.001); *p < 0.05 represents significant longitudinal changes between 3- and 6 months within each group; Mann Whitney U-test: p < 0.05 represents significant differences between treatment groups. BAS, baseline; control group, 1-h debridement with regular checkups; test group, 1-h debridement with limited oral hygiene reinforcement; PI, plaque index; BOP, bleeding on probing; PPD, probing pocket depth; CAL, clinical attachment levels. Microbiological parameters At 3- and 6-months from baseline, the numbers of P. gingivalis, T. forsythia and T. denticola were significantly reduced after both treatment approaches (p < 0.001) (Table 6), whereas no significant improvements were noted between 3- and 6- months. At 3-months the reduction of P. gingivalis was significantly greater in the control group compared to the test group (p < 0.05), while this finding just failed to reach statistical significance at 6-months (p = 0.05). Similar numbers of T. forsythia and T. denticola were found between groups at all time points. Discussion Current data demonstrated that the simplified treatment protocol of moderately advanced CPP, which comprises 1-h full-mouth ultrasonic debridement with no use of antiseptics under local anaesthesia when necessary and careful oral hygiene measures (control group) resulted in significant clinical and microbiological improvements at three and six months. Despite the fact that overall improvements reported in this study were of a smaller magnitude than those presented by Wennstr om et al. (2005), both studies suggest that this single visit compact periodontal treatment is a justified initial treatment approach. Interestingly, reassessment of moderately deep sites after three and six months revealed that changes in PPD and CAL were comparable with those reported by Wennstr om et al. (2005). However, a greater clinical improvement was noted at deep sites in this study, which was evident in the control group. It should be noted that

6 154 Apatzidou et al. Table 5. Linear Mixed Model to log-ppd data of 6006 sites in 44 subjects over three time-points Type III tests of fixed effects Estimated anti-log mean values with 95% CI Source Numerator df Denominator df F p-value Group Visit PI Mean LB UB Intercept <0.001 Control Group Visit < PI < Group 9 Visit Group 9 PI Visit 9 PI <0.001 Test Group 9 Visit 9 PI Estimates of covariance parameters (SE) Residual: 1.56 (0.01) Visit 1 (time + visit (patient)): (0.04) Intercept (patient 9 tooth 9 site): 1.71 (0.02) Visit 2 (time + visit (patient)): (0.21) Intercept (time + visit (patient)): 1.32 (1.32) Visit 3 (time + visit (patient)): 1.12 (0.02) Group: control group, 1-h debridement with regular checkups; test group, 1-h debridement with limited oral hygiene reinforcement; Visit: visit 1 = baseline, visit 2 = three months, visit 3 = six months; PI (plaque index): PI = 1 in presence of plaque, PI = 0 in absence of plaque; PPD = probing pocket depth at 1001 teeth in total. Table 6. Mean (SD) numbers (910 5 ) of the three species tested N control group = 22 N test group = 22 BAS 3 months 6 months Change (BAS 3 months) Change (BAS 6 months) Change (3 6 months) Porphyromonas gingivalis Control group * Test group Tannerella forsythia Control group Test group Treponema denticola Control group Test group BAS, baseline; control group, 1-h debridement with regular checkups; test group, 1-h debridement with limited oral hygiene reinforcement. Wilcoxon s signed-rank test: significant longitudinal changes were noted at 3- and 6-months from baseline within each group (p < 0.001); no significant longitudinal changes were noted between 3- and 6-months (p > 0.05); Mann Whitney U-test: *p < 0.05 represents significant differences between treatment groups. although the control group was regularly followed, it appeared to be less compliant with OHI during the initial phase of treatment, compared with the full-mouth ultrasonic debridement group in the previous report. In the quoted study patients received thorough instructions in plaque control at the screening visit prior to treatment and this resulted in lower plaque scores at baseline compared with the present study (23% versus 83%), which might have contributed to an easier management of the whole-mouth condition in 1 h. The 6-month data of this study revealed that the degree of improvement in PPD and CAL seen in both groups was within the range of clinical improvement reported in early studies that had mean initial PPD of mm (Cobb 2002). Interestingly, in the time interval between baseline and three months a lower decrease in the numbers of P. gingivalis, in addition to smaller fullmouth improvements in PI and BOP were noted in the test group over the control group, while this inter-group discrepancy disappeared between three and six months resulting in greater PPD reductions for the test group. This pattern was also followed by moderately deep sites in the test group, which showed a significantly greater reduction in PPD after receiving additional treatment at three months. Deep sites improved in a similar manner after both treatment approaches with regard to PPD and CAL, but after the 3-month re-treatment visit they demonstrated a greater decrease in BOP in the test group. Presence of plaque in the control group resulted in no significant differences in PPD levels between 3- and 6-months, in contrast to the test group in which PPD improved at this time interval in presence of plaque, indicating that subjects in the latter group benefited the most from the 3-month re-treatment visit. However, in absence of plaque both groups showed significant PPD improvements over time. By including the test group, the current study simulated the situation where in a dental practice a periodontitis patient can afford mini-

7 Simplified periodontal treatment 155 mum time and fees for treatment and therefore, professional biofilm and calculus removal in addition to OHI and motivation should be careful, concise and carried out in a single visit. Short treatment regimes may constitute a paradigm shift in periodontal practice in modern years where there are serious practical considerations (Kinane 2005), but it remained to determine what the treatment outcome of this compact scheme would be when no follow-up visits are incorporated into the treatment plan during the initial phase of treatment, and whether this treatment outcome could be maintained in the longer term. Interestingly, Wennstr om et al. (2005) demonstrated that at six months approximately 50% of the initially deep pockets still remained as non-successful sites (>4 mm) for both the simplified and the traditional treatment schemes and this finding poses a clinical dilemma as to whether repeated instrumentation or other treatment such as surgical or antibiotic should be employed in order to achieve high percentages of closed pockets. These data emphasize that the simplified treatment of 1 h is evaluated as an efficacious initial treatment approach and additional treatment and long-term monitoring of these periodontitis cases should be incorporated into the treatment plan to maintain a successful treatment outcome. However, the subjects from the previous study were followed up for 1 year and no significant differences in the incidence of disease recurrences were noted between the traditional and the simplified treatment schemes, indicating that ultrasonic instrumentation successfully removes subgingival deposits and biofilms (Tomasi et al. 2006). In this study, despite the prophylaxis given at three months, the 6- month re-assessment revealed that the patients who had a single session of oral hygiene reinforcement during the initial phase of treatment had still high scores of plaque and BOP (31% and 34%, respectively), which is not very promising for the long-term periodontal stability. It has been shown that periodontal health was not maintained and further breakdown occurred in patients with an infrequent recall programme and a poor plaque control (Nyman et al. 1975, 1977, Axelsson & Lindhe 1981b). The greater overall PPD reduction and especially in moderately deep sites which was noted in the test group after the 3-month re-treatment visit highlights the necessity of a regular recall system in these subjects in order to maintain the treatment outcome and compensate for the relatively low levels of oral hygiene and high bleeding indices. It has been shown that effective supragingival plaque control is essential to succeed long-term control of inflammatory periodontal disease (Lindhe & Nyman 1975, 1984, Axelsson & Lindhe 1981a,b), and this is in line with current data which showed the negative effect that plaque had on PPD for both treatments over the three time-points. Early reports have pointed out that OHI given once as in the test group will not result in a permanent improvement of the oral hygiene status (Massler et al. 1957, Ash et al. 1964), suggesting that in general, the long-lasting maintenance of plaque control seems to be dependent on regularly reiterated tooth cleaning instructions (Nyman et al. 1977). A classical paper by Pihlstrom et al. (1981) demonstrated that it may be possible to arrest the progress of destructive periodontal disease even in presence of relatively poor plaque control, without implying that plaque control should be of little concern to the patient or the therapist. The authors concluded that appropriate periodontal therapy coupled with frequent recall prophylaxis is a necessity for successful therapy. In line with these findings, this study demonstrated additional treatment effects including the primary outcome variable for the test group after receiving professional care at three months. It may well be that a longer period than three months is required to evidence the effects of undisturbed plaque accumulation on pocket depth levels, as no treatment effect on PPD measurements was found in presence of plaque and this evidence emerged from both the multilevel and the non-parametric analyses. Current findings highlight the great importance of the 3-month recall visit, which resulted in the equalisation of the interim differences in bleeding and plaque scores and in numbers of P. gingivalis and also in greater improvements in PPD between the least and the most closely followed study groups. In conclusion, despite the practical values and the efficacy of the 1-h full-mouth debridement coupled with a single session of OHI as an initial treatment approach, this simplified treatment resulted in greater plaque and bleeding scores and numbers of P. gingivalis at three months; plaque had a detrimental effect on PPD for either treatment over the three timepoints; professional mechanical removal of dental biofilm on a 3- month basis is important in subjects with compromised plaque control, and resulted in greater PPD reduction and equalisation of the shortterm inter-group differences. Acknowledgements We thank Apostolos Mavidis for his technical assistance and Dr Vassilis Karagiannis, School of Mathematics, AUTh, for his statistical advice. References Altman, D. G., Schulz, K. F., Moher, D., Egger, M., Davidoff, F., Elbourne, D., Gotzsche, P. C. & Lang, T. (2001) The revised CONSORT statement for reporting randomised trials: explanation and elaboration. 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8 156 Apatzidou et al. periodontal therapy? Journal of Clinical Periodontology 32, Koshy, G., Kawashima, Y., Kiji, M., Nitta, H., Umeda, M., Nagasawa, T. & Ishikawa, I. (2005) Effects of single-visit full-mouth ultrasonic debridement versus quadrant-wise ultrasonic debridement. Journal of Clinical Periodontology 32, Lindhe, J. & Nyman, S. (1975) The effect of plaque control and surgical pocket elimination on the establishment and maintenance of periodontal health. A longitudinal study of periodontal therapy in cases of advanced disease. Journal of Clinical Periodontology 2, Lindhe, J. & Nyman, S. (1984) Long-term maintenance of patients treated for advanced periodontal disease. Journal of Clinical Periodontology 11, Massler, M., Rosenberg, H. M., Carter, W. & Schour, I. (1957) Gingivitis in young adult males: lack of effectiveness of a permissive program of toothbrushing. Journal of Periodontology 28, Nyman, S., Lindhe, J. & Rosling, B. (1977) Periodontal surgery in plaque-infected dentitions. Journal of Clinical Periodontology 4, Nyman, S., Rosling, B. & Lindhe, J. (1975) Effect of professional tooth cleaning on healing after periodontal surgery. Journal of Clinical Periodontology 2, O Leary, T. J., Drake, R. B. & Naylor, J. E. (1972) The plaque control record. Journal of Periodontology 43, 38. Pihlstrom, B. L., Ortiz-Campos, C. & McHugh, R. B. (1981) A randomized four-years study of periodontal therapy. Journal of Periodontology 52, Quirynen, M., Mongardini, C., de Soete, M., Pauwels, M., Coucke, W., van Eldere, J. & van Steenberghe, D. (2000) The r^ole of chlorhexidine in the one-stage full-mouth disinfection treatment of patients with advanced adult periodontitis. Long-term clinical and microbiological observations. Journal of Clinical Periodontology 27, Socransky, S. S., Smith, C., Martin, L., Paster, B. J., Dewhirst, F. E. & Levin, A. E. (1994) Checkerboard DNA DNA hybridisation. BioTechniques 17, Tomasi, C., Bertelle, A., Dellasega, E. & Wennstr om, J. L. (2006) Full-mouth ultrasonic debridement and risk of disease recurrence: a 1-year follow-up. Journal of Clinical Periodontology 33, Waerhaug, J. (1981) Effect of toothbrushing on subgingival plaque formation. Journal of Periodontology 52, Wennstr om, J. L., Tomasi, C., Bertelle, A. & Dellasega, E. (2005) Full-mouth ultrasonic debridement versus quadrant scaling and root planing as an initial approach in the treatment of chronic periodontitis. Journal of Clinical Periodontology 32, West, B. T., Welch, K. B. & Galecki, A. T. (2007) Linear mixed models: a practical guide using statistical software. Boca Raton: Chapman & Hall/CRC. Address Danae A. Apatzidou School of Dentistry, Department of Preventive Dentistry, Periodontology and Implant Biology, Aristotle University of Thessaloniki, Thessaloniki Greece perioapatzidou@yahoo.gr Clinical Relevance Scientific rationale for the study: As periodontal treatment schemes tend to become compact in terms of frequency of sessions and duration of each session, it remains to determine whether the overall time frame of non-surgical periodontal therapy has an impact on the treatment outcome. Principal findings: The clinical and microbiological outcome of the simplified periodontal treatment of 1-h ultrasonic debridement and OHI was enhanced following additional treatment, which was given at 3 months. Practical implications: The simplified treatment of 1-h full-mouth debridement with and without frequent sessions of OHI and motivation seems to be efficacious as an initial treatment approach of CPP.