TITLE: Non-surgical instrumentation associated with povidone-iodine in the
treatment of interproximal furcation involvements

  ABSTRACT.OBJECTIVE:
The aim of this controlled clinical trial was to evaluate the effect of topically
applied povidone-iodine (PVP-I) used as an adjunct to non-surgical treatment of
interproximal class II furcation involvements. 

ABSTRACT.MATERIAL AND METHODS:
Thirty-two patients presenting at least one interproximal class II furcation
involvement that bled on probing with probing pocket depth (PPD) ≥5 mm were
recruited. Patients were randomly chosen to receive either subgingival
instrumentation with an ultrasonic device using PVP-I (10%) as the cooling liquid
(test group) or identical treatment using distilled water as the cooling liquid
(control group). The following clinical outcomes were evaluated: visible plaque
index, bleeding on probing (BOP), position of the gingival margin, relative
attachment level (RAL), PPD and relative horizontal attachment level (RHAL). BAPNA
(N-benzoyl-Larginine-p-nitroanilide) testing was used to analyze trypsin-like
activity in dental biofilm. All parameters were evaluated at baseline and 1, 3 and
6 months after non-surgical subgingival instrumentation. 

ABSTRACT.RESULTS:
Six months after treatment, both groups had similar means of PPD reduction, RAL
and RHAL gain (p>0.05). These variables were, respectively, 2.20±1.10 mm,
1.27±1.02 mm and 1.33±0.85 mm in the control group and 2.67±1.21 mm, 1.50±1.09 mm
and 1.56±0.93 mm in the test group. No difference was observed between groups at
none of the posttreatment periods, regarding the number of sites showing clinical
attachment gain ≥2 mm. However, at 6 months posttreatment, the test group
presented fewer sites with PPD ≥5 mm than the control group. Also at 6 months
the test group had lower BAPNA values than control group. 

ABSTRACT.CONCLUSION:
The use of PVP-I as an adjunct in the non-surgical treatment of interproximal
class II furcation involvements provided limited additional clinical benefits.

BODY.INTRODUCTION:
Furcation involvements represent a great challenge to the success of periodontal
therapy12. The reduced rate of
success experienced in the treatment of furcation involvements seems to result from the
incomplete removal of subgingival plaque and calculus in the interadicular area owing to
the peculiar anatomy of the furcation space24,25. In addition, the
distal location and the specific root configuration of molars limit adequate plaque
control by the patient3.  Regarding the therapeutic approach, although furcation involvement treated with a
conservative approach does not yield the same satisfactory results as single-rooted
teeth or molar flat surfaces, it has been shown that teeth with furcation involvement
have a remarkable survival rate following conservative treatment21. These findings demonstrate that the
conservative approach for furcation involvement can be performed with the expectation of
a high long-term survival rate for the patients demonstrating a satisfactory plaque
control3.  Del Peloso Ribeiro, et al.7 (2006)
showed in a randomized controlled clinical trial that non-surgical therapy can
effectively treat buccal and lingual class II furcation involvements. However, Del
Peloso Ribeiro, et al.8 (2007) also
showed that buccal and lingual class II furcation involvements respond better to
non-surgical therapy than interproximal class II furcation involvements.  In an attempt to improve the biological response of interproximal furcation involvement
to nonsurgical periodontal therapy chemotherapeutic agents could be used.
Povidone-iodine (PVP-I) is one of the most potent and widely used broad-spectrum
antiseptics available. It has a very rapidly bactericidal effect, being effective
against periodontal pathogens in vitro in as little as 15 s of contact
and in vivo within 5 min of contact4,11. PVP-I also fails to
allow the development of bacterial resistance; has low systemic toxicity and low
financial cost2,15. In addition, allergic sensitization to PVP-I is
rare28.  PVP-I has been used as an adjunct in the treatment of chronic periodontitis with
promising results27.Rosling,et
al.26 (2001) showed that PVP-I,
used as the cooling liquid of an ultrasonic device, in conjunction with subgingival root
debridement improved the outcome of non-surgical therapy in non-molar teeth. Hoang, et
al.13 (2003) also demonstrated
in non-molar teeth that the addition of subgingival PVP-I irrigation to conventional
mechanical therapy caused a greater reduction in total pathogen counts.  The aim of the present study was to evaluate the effect of PVP-I, used as the cooling
liquid of an ultrasonic device in the non-surgical treatment of interproximal class II
furcation involvements.

BODY.MATERIAL AND METHODS.STUDY POPULATION:
Thirty-two subjects were recruited from those referred for treatment to the
Department of Periodontology of Piracicaba Dental School, State University of
Campinas, Brazil. Subjects were enrolled from October 2005 to June 2006. All patients
were individually informed about the nature of the proposed treatment and informed
consent forms were signed. The study protocol was approved by the local Research
Ethics Committee.  Power analysis indicated that 13 subjects would have 88% power to detect a 1-mm
difference in clinical attachment level between the two groups. Subjects who were
invited to participate met the following inclusion criteria: 1) diagnosis of severe
chronic periodontitis by the presence of periodontal pockets with clinical attachment
loss ≥5 mm, bleeding on probing and radiographic bone loss9; 2) at least one molar
with class II interproximal furcation involvement10 that bled on probing, with probing pocket depth ≥5 mm.
Exclusion criteria were: 1) furcation involvement in molars with periapical disease;
2) medical disorders that could influence the response to treatment; 3) scaling and
root planing in the preceding 6 months; 4) consumption of drugs known to affect
periodontal status within the past 6 months; 5) pregnancy; 6) allergy to iodine; 7)
thyroid dysfunction and 8) smoking habits.

BODY.MATERIAL AND METHODS.STUDY DESIGN:
This was a randomized parallel arm clinical trial with six months of duration.
Patients initially received detailed information on the etiology of periodontal
disease and instructions in proper self-performed plaque control measures,
interdental cleaning with dental floss and interdental toothbrushes. In the initial
sessions, patients also had plaque retentive factors (caries, excess of restorations
and supragingival calculus) removed. The baseline measurements were performed 21 days
after this initial phase.  All teeth with periodontal pocket ≥5 mm that bled on probing were treated with
scaling and root planing (basic therapy). The non-surgical therapy on molars with
furcation involvement was performed under local anesthesia by the use of an
ultrasonic device (Profi III, Dabi Atlante, Ribeirão Preto, SP, Brazil). Specific
furcation tips were used (33R and 33L; Amdent, Stockholm, Sweden). The
instrumentation of furcation involvements in the test group was combined with the
administration of 10% PVP-I. In this group, the traditional cooling liquid of the
ultrasonic device was replaced by PVP-I for the treatment of the interproximal
furcation. Thus, not all the pathological sites of the test group received PVP-I. The
furcation involvements of the control group received an identical treatment, but
distilled water was used as the cooling liquid. The randomization was done by coin
toss right after the patient was included in the study. The allocation concealment
was secured by having a person not involved in the study performing the
randomization. This person was different from the one responsible for the treatment
(S. B.) and different from the examiner (E. D. P. R.). The person responsible for the
treatment was a specialist in periodontics. The randomization code was not broken
until all data had been collected. Thus, the treatment group was not revealed to the
clinical examiner or to the statistician.  Only one clinician was responsible for administering the treatment throughout the
course of the study. This clinician was different from the calibrated examiner
performing the clinical measurements. The furcation involvements were instrumented
until a smooth, hard surface was achieved.  After the active treatment, all subjects were included in a maintenance program
composed of professional supragingival plaque control and reinforcement of oral
hygiene instructions every 15 days for the first month and every month until the
sixth month. At the 3-month recall visit, sites that exhibited probing pocket depth
≥5 mm and bled on probing received subgingival therapy identical to that provided
during the phase of basic therapy. The maintenance program also included an update of
the medical and dental histories, extraoral and intraoral soft tissue examination,
dental examination and periodontal evaluation.

BODY.MATERIAL AND METHODS.CLINICAL MEASUREMENTS:
The following clinical parameters were taken at baseline and at 1, 3 and 6 months
after therapy. Visible plaque index (VPI)1 evaluated supragingival plaque accumulation dichotomously at
six sites on all teeth in the mouth. Bleeding on probing (BOP)18 was also measured dichotomously at
six sites per tooth. Thus, VPI and BOP were calculated as full mouth percentage of
presence of plaque and BOP.  An individual stent was fabricated of clear self-curing resin, with a vertical groove
at the place where the furcation involvement could be probed to create fixed
landmarks and to standardize the location of periodontal probes at the furcation
sites. The position of the gingival margin (PGM) was measured from the stent to the
gingival margin and the relative attachment level (RAL) from the stent to the bottom
of the periodontal pocket. The probing pocket depth (PPD) was calculated based on RAL
and PMG. The relative horizontal attachment level (RHAL) was measured, using a curved
periodontal probe (Neumar, São Paulo, SP, Brazil) with grooves at 1 mm
intervals29 from the stent to
the deepest horizontal point of the periodontal pocket. The clinical parameters VPI,
BOP, PGM, RAL and PPD were measured using a standardized periodontal probe with 1 mm
markings (PCPUNC 15®; Hu-Friedy, Chicago, IL, USA).

BODY.MATERIAL AND METHODS.EXAMINER CALIBRATION:
The investigator charged with clinical assessments was calibrated for intraexaminer
repeatability prior to the start of the trial. Three patients with chronic
periodontitis were enrolled for this purpose. Duplicate measurements (N=414) for PPD,
RAL and RHAL were collected with an interval of 24 h between the first and the second
recording. The intraclass correlation coefficients as a measure of intraexaminer
reproducibility were 0.81, 0.88 and 0.89 for mean PPD, RAL and RHAL,
respectively.

BODY.MATERIAL AND METHODS.BIOCHEMICAL EVALUATION - BAPNA ASSAY:
The biochemical evaluation was done with the BAPNA test that permits the detection of
microorganisms possessing trypsin-like enzymes such as Tannerella
forsythensis, Treponema denticola and Porphyromonas
gingivalis. Subgingival dental plaque was collected from furcation
involvements with sterile Gracey curettes. Before the collection, the area was dried,
isolated and had the supragingival plaque removed.  The plaque collected was placed in preweighed coded microcentrifuge tubes. To the
tubes was added 1 mL of a solution containing the enzyme substrate
N-benzoyl-L-arginine-p-nitroanilide (BAPNA; Sigma, St. Louis, MO, USA) with a final
concentration of 1.0 nmol/L in the assay buffer (0.05 nmol/L Tris-HCl, 5 mM
CaCl2, pH 7.5) that had 5% DMSO. This suspension was vortexed and then
placed in an ultrasound bath on ice for 10 min with 2-s cycles and 2-s intervals at
17 W using a 100 W ultrasonic processor. After 17 h of incubation at 37oC, the
reaction was stopped with ice and by the addition of 100 mL of glacial acetic acid.
The absorbance was read at 405 nm. The results were given in nanomoles of product per
minute per milligram of dental plaque wet weight20.

BODY.MATERIAL AND METHODS.STATISTICAL ANALYSIS:
Repeated measures analysis of variance (ANOVA) was used to detect intra and
intergroup differences in clinical parameters (VPI, BOP, PPD, RAL and RHAL). When
statistical significance was found, analysis of the difference was determined using
the method of Tukey. The proportion of sites presenting PPD ≥5 mm, RAL gain ≥2
mm, plaque and bleeding on probing at the furcation sites and number of lesions
retreated at 3 and 6 months were compared between groups with chi-square analysis or
Fischer's exact test. The Friedman test was used to detect intragroup differences in
biochemical parameter among all periods and the Mann-Whitney test to detect
intergroup differences in this parameter at each time interval. All evaluations used
the subject as the unit of measurement; averages were used if more than one site per
subject existed. Individual furcation involvements were compared regarding the RAL
gain ≥2 mm, the occurrence of BOP, and the number of sites referred for treatment
and PPD ≥5 mm. All analysis was done with SAS Software 2001-Release 8.2 (SAS
Institute Inc., Cary, North Carolina, USA). An experimental level of significance
(alpha) was set at 0.05. RAL was considered as the primary outcome variable. All
other parameters were considered secondary outcomes.

BODY.RESULTS:
Four patients did not show up for all the appointments, for reasons not related to the
study; and thus, a total of 28 patients completed the study: 15 of the control group and
13 of the test group. A total of 37 furcation involvements were evaluated: 18 in the
control group and 19 in the test group. The baseline data indicated that control and
test groups were similar according to age, gender, clinical and biochemical parameters
(Table 1).   Table 1 Baseline means (± standard deviation) of age, gender, clinical and biochemical
parameters * CARACTERISTIC CONTROL GROUP TEST GROUP       Age (range/ mean) 26-57/ 42.96 years 27-59/ 43.74 years % Males 47.37% 46.15% VPI (%)† 45.30 (±13.08) 43.96 (±16.02) BOP (%) 34.60 (±11.05) 31.83 (±13.91) PGM (mm) 2.35 (±0.68) 2.31 (±1.03) PPD (mm) 6.98 (±1.53) 7.00 (±1.00) RAL (mm) 9.33 (±1.64) 9.31 (±1.07) RHAL (mm) 10.22 (±3.07) 10.97 (±1.72) BAPNA (nmol/mg x min) 37.45 (±26.18) 45.97 (±22.22) * At baseline, no significant differences were noted in demographic, clinical or
biochemical parameters between groups (analysis by non-paired t test for age,
by repeated measures ANOVA for clinical parameters and by Mann-Whitney test for
biochemical parameter † Note: Values of VPI and BOP refer to means of the whole mouth while values of
PPD, CAL, RHAL and BAPNA refer to means of the furcation site  VPI= visible plaque index; BOP= bleeding on probing; PGM= position of the
gengival margin; PPD= probing pocket depth; RAL= relative attachment level;
RHAL= relative horizontal attachment level; BAPNA=
N-benzoyl-L-arginine-p-nitroanilide 

BODY.RESULTS.VISIBLE PLAQUE INDEX (VPI) AND BLEEDING ON PROBING (BOP):
VPI and BOP were reduced during the study in both groups, but no statistically
significant difference was found between them (Table
2). BOP were measured for the whole mouth and also exclusively at the
furcation involvements. In this case, no difference was observed between groups
(Figure 1).   Table 2 Mean ± SD of visible plaque index (VPI) and bleeding on probing (BOP) values
(%) at different time intervals for control and test groups * TIME INTERVAL CONTROL GROUP TEST GROUP   VPI baseline 45.29±13.08 43.95±16.02 1 month 39.74±16.39 46.21±13.19 3 months 35.24±13.98 ** 32.52±10.34 ** 6 months 34.57±12.09 ** 30.51±13.96 ** BOP baseline 34.60±11.04 31.83±13.91 1 month 25.01±9.44 *** 21.03±11.08 *** 3 months 21.47±10.13 *** 19.23±8.47 *** 6 months 19.98±6.07 *** 18.37±8.07 *** * No significant differences were noted in VPI and BOP, of all teeth, between
groups (analysis by repeated measures ANOVA) ** Significant reduction (p<0.05) from baseline and 1 month values (analysis
by repeated measures ANOVA and Tukey test) *** Significant reduction (p<0.05) from baseline (analysis by repeated
measures ANOVA and Tukey test)   Figure 1Bleeding on probing (BOP) of furcation involvements at different time intervals
for control and test groups

BODY.RESULTS.CLINICAL PARAMETERS - PGM, PPD, RAL AND RHAL:
Both groups showed, without significant difference between them, an increase in PGM,
a reduction in PPD and a gain in RAL and RHAL (Table
3). At 6 months, the mean decrease in PPD was 2.20±1.10 mm in control group
and 2.67±1.21 mm in test group. The mean gain in RAL and RHAL was 1.27±1.02 mm and
1.33±0.85 mm in the control group and 1.50±1.09 mm and 1.56±0.93 mm in the test
group, respectively. The results of PMG, PPD, RAL and RHAL refer strictly to the
furcation sites.   Table 3 Mean ± standard deviation of position of the gengival margin (PGM), probing
pocket depth (PPD), relative attachment level (RAL) and relative horizontal
attachment level (RHAL) (mm) at different time intervals for control and test
groups TIME INTERVAL CONTROL
GROUP TEST
GROUP   PGM Baseline 2.40±1.06 2.00±0.97 1 month 3.00±1.11 * 2.89 ±1.13 * 3 months 3.13±0.94 * 3.22±1.00 * 6 months 3.33±0.99 * 3.17±1.20 * PPD Baseline 7.10±1.71 7.11±1.67 1 month 5.13±1.2 * 5.05±1.16 * 3 months 5.00±1.26 * 4.83±1.29 * 6 months 4.90±0.96 * 4.44±1.19 * RAL Baseline 9.50±2.05 9.11±1.81 1 month 8.13±1.57 * 7.94±1.62 * 3 months 8.13±1.63 * 8.05±1.39 * 6 months 8.23±1.30 * 7.61±1.46 * RHAL Baseline 11.20±2.34 10.61±2.20 1 month 10.00±1.89 * 10.17±2.55 * 3 months 9.73±1.64 * 9.72±2.05 * 6 months 8.87±1.65 * 9.05±1.70 * * Significant difference from baseline value (analysis by ANOVA and Tukey
test)   There was no difference between groups regarding the proportions of furcation
presenting RAL gain ≥2 mm. At the first month after treatment, the control group
had 36.67% of sites showing a RAL gain ≥2 mm and the test group had 42.10%. At 3
months, these values were 30.00% and 26.31% and at 6 months, 33.33% and 42.10%,
respectively.  Difference between groups was found regarding the proportion of sites with PPD ≥5
mm at 6 months after treatment (Figure 2). All
furcations presented PPD ≥5 mm at baseline. At the first month after therapy,
70.00% of the furcation involvements still had PPD ≥5 mm in the control group and
52.63% had this PPD in the test group. At 3 months, the values were 66.67% and
52.63%, respectively. At 6 months, 70.00% of the evaluated sites had PPD ≥5 mm in
the control group and 36.84% in the test group (p=0.04).  Figure 2Percentage of furcation involvements with probing pocket depth (PPD) ≥5 mm
atdifferent time intervals for control and test groups.* Difference (p<0.05) between groups by chi-square test.  The percentage of furcation sites that needed retreatment at 3 months was 43.33% in
the control group and 36.84% in the test group. At 6 months, the values were 33.33%
and 15.79%, respectively. These differences were not statistically different (Figure 3).  Figure 3Percentage of furcation involvements that needed re-treatment at different time
intervals for control and test groups

BODY.RESULTS.BIOCHEMICAL PARAMETER - BAPNA TEST:
Table 4 presents the results of BAPNA at
different time intervals. Both groups, at one and three months after treatment,
showed a statistically significant reduction of the trypsin-like enzyme activity in
subgingival biofilm, without difference between groups. At 6 months, only the test
group presented BAPNA value significantly different from baseline. There was also a
significant difference between groups on BAPNA values at 6 months.   Table 4 N-benzoyl-L-arginine-p-nitroanilide (BAPNA) results (nmol product/mg dental
biofilm/minute) at different time intervals for control and test groups (mean ±
standard deviation) TIME INTERVAL BAPNA CONTROL GROUP TEST GROUP       Baseline 37.45±26.18 45.97±22.22 1 month 21.58±24.87 * 17.95±8.76 * 3 months 17.59±15.71 * 23.38±20.88 * 6 months 39.98±38.14† 18.10±14.61 * † * Significant difference from baseline value (analysis by Friedman test) † Significant difference between groups (analysis by Mann-Whitney test) 

BODY.DISCUSSION:
The conservative approach of furcation involvements is effective in the treatment of
buccal and lingual class II furcation lesions in patients demonstrating a satisfactory
plaque control7. However,
interproximal furcation involvements do not show the same biological response to
non-surgical treatment probably because of the irregular anatomy of the area that
impairs professional plaque control procedures and because of the difficulties faced by
the patient to maintain plaque control3,8. In an attempt to
overcome these difficulties antimicrobials agents could be used. Because PVP-I is a
potent antiseptic and its use in the treatment of non-molar teeth with chronic
periodontitis has shown promising results13,26, the present study has
been designed to evaluate the use of locally applied PVP-I as an adjunct to nonsurgical
therapy of interproximal class II furcation involvements.  However, in the present study, both groups presented similar means of PPD reduction and
RAL and HRAL gain. No benefit on the use of antimicrobials in the treatment of class II
mandibular furcation was also shown by Tonetti, et al.30 (1998).  In the present study, difference between groups was observed, at 6 months, in BAPNA
values. Test group had lower levels of trypsin-like activity than the control group.
Trypsin-like enzyme is produced by important periodontal pathogens such as
Tannerella forsythia, Treponema denticola and Porphyromonas
gingivalis and is associated with signs of periodontitis32. These microorganisms are increased in
diseased sites, when compared to stable ones22. Strong evidence also supports the report of T. forsythia
and P. gingivalis as risk indicators of periodontal
disease33. This information
raises the doubt if the lower values of BAPNA in the group where PVP-I was used will be
followed by a lower average of disease recurrence.  The BAPNA results could be related to the higher percentage of sites presenting, at 6
months, PPD ≥5 mm in the control group than in the test group. This is an important
result since according to Claffey and Egelberg6 (1995) patients demonstrating a high proportion of deep pockets
following initial cause related therapy are more likely to experience further clinical
attachment loss.  However, no difference was observed in the number of sites referred for re-treatment.
This parameter is an important indicator of the clinical significance of treatment
because it relates to the percentage of sites that returned to health and to the
percentage of sites still requiring therapy14. Sites with PPD ≥5 mm and BOP were re-treated. BOP is an
important outcome measurement as the absence of bleeding on probing in recall patients
has been associated with clinical stability over time16. BOP and PPD are the accepted indicators of the response
to root debridement31. At 3 and 6
months after therapy the percentage of sites re-treated was 30.00% and 33.33% in the
control group and 26.31% and 42.10% in the test group, respectively. This means that at
6 months only 66.67% of control group and 58.90% of test group had PPD ≤5 mm without
BOP.  Interproximal furcation involvements are difficult to treat not only with non-surgical
therapy, but also with guided tissue regeneration. In a regeneration furcation study,
the largest clinical improvement was found in class II furcation defects of mandibular
molars, followed by buccal class II furcations of maxillary molars and, interproximal
furcation lesions exhibiting the least or no improvement23.  The difficulties in the treatment of interproximal furcation involvement could not be
overcome by the use of PVP-I as adjunct to non-surgical therapy even with the use of
ultrasonic tips specifically design to access the furcation area. These tips were used
since it is known that areas inaccessible to instruments are also inaccessible to the
cooling liquid. Also it has been shown that furcation entrances have in general smaller
dimensions than the width of a Gracey curette, but they are larger than the average
dimension of a new standard ultrasonic tip5. This is in accordance with the finding that ultrasonic instruments
are more effective than hand scaling in reducing gingival fluid flow and bacterial
proportions of spirochetes and other motile organisms in class II and III furcation
involvements17.  The decision to employ a 10% solution of PVP-I was based on findings by Nakagawa, et
al.19 (1990). They determined
that only the in vivo undiluted PVP-I solution significantly reduced
the total colony forming units of subgingival pockets. Other in vitro
studies showed bactericidal effect with lower concentration of PVP-I27. However, in vitro data
may not reflect in vivo results because intraoral findings can be
affected by salivary dilution, protein deactivation, and the inability of drugs to
penetrate bacterial biofilms. Hoang, et al.13 (2003) also used 10% PVP-I subgingival irrigation in
periodontitis lesions showing radiographic evidence of subgingival calculus.

BODY.CONCLUSION:
It may be concluded, based on the design of the study, that the use of PVP-I, as the
cooling liquid of an ultrasonic device in the non-surgical treatment of interproximal
class II furcation involvements provided limited additional clinical benefits.

Question: Compared to identical treatment using distilled water as the cooling liquid (control group). what was the result of subgingival instrumentation with an ultrasonic device using PVP-I (10%) as the cooling liquid (test group) on relative attachment level (RAL)?
Evidence: Six months after treatment, both groups had similar means of PPD reduction, RAL
and RHAL gain (p>0.05). 
Answer: no significant difference