Masticatory satisfaction , ability , and performance in partially dentate patients after periodontal therapy

Introduction: Understanding the effects of periodontal therapy is essential in performance and satisfaction of partially dentate patients. Objective: To assess the effect of subgingival periodontal treatment in performance and masticatory satisfaction and ability as reported by partially dentate patients with untreated chronic periodontitis. Materials and method: Patients were given nonsurgical periodontal treatment and masticatory satisfaction, ability, and performance were evaluated before and after treatment. Performance was assessed based on sieving chewed standardized chewable material, while satisfaction and ability were analyzed using a questionnaire based on OHIP-EDENT. Result: Mean numbers of functional tooth units were 10.36 ± 1.43 anterior and 6.73 ± 0.79 posterior teeth. Masticatory performance did not vary significantly (p = 0.075), and mean particle sizes before and after treatment were 4.23 ± 1.84 mm and 3.90 ± 0.75 mm, respectively. Overall satisfaction and ability scores after treatment were higher (p > 0.05) compared with scores prior to the periodontal intervention. Conclusion: Periodontal treatment improves masticatory satisfaction and ability with no effect on performance. Descriptors: Clinical study; mastication; periodontitis; periodontal disease.


INTRODUCTION
Controlled by reflex arcs from the nervous system, mastication in humans is a complex process influenced by a balanced relationship between teeth, muscles, and joints 1 .Reduction in the number of functional tooth units (FTUs), also called tooth loss, negatively affects mastication and trituration patterns, and periodontitis is one of the main causes behind the decrease in the number of teeth 2,3 .Characterized by tooth mobility, the main manifestation of periodontitis is its chronic form, which evolves to loss of the 361/364 tooth involved.This process starts with the destruction of the periodontium and loss of insertion, which is often asymptomatic 4,5 .
In view of the specific characteristics of periodontitis, research has looked into the relationship between periodontal diseases and the masticatory process, and found that these conditions may be responsible for dysfunctional mastication.This relationship has been investigated from different research perspectives.While some studies have focused on the correlation between periodontal status and masticatory capacity in the effort to establish a direct link between clinical parameters and mastication [6][7][8][9][10][11][12] , others have examined the association of tooth loss 13,14 and/or loss of insertion 15 with masticatory efficiency and bite force.As a rule these studies show that tooth loss and periodontal disease negatively affect overall satisfaction and masticatory ability of individuals.
However, despite the large number of studies published on this subject, there is a knowledge gap concerning the way periodontitis patients assess their own masticatory satisfaction and the effect of periodontal disease on masticatory behavior.In this scenario, the present study evaluated the effect of subgingival periodontal treatment on masticatory performance and self-reported ability and satisfaction in partially dentate patients.

MATERIAL AND METHOD
This clinical study included chronic periodontitis patients who had lost FTUs and spontaneously looked for dental treatment in the Odontology Service Units of Universidade Luterana do Brasil (ULBRA) in the greater Porto Alegre region, state of Rio Grande do Sul, Brazil.Inclusion criteria were (i) untreated chronic periodontitis, (ii) presence of at least 16 teeth with maximum loss of insertion of 5 mm, (iii) presence of dental occlusion between four and six pairs of posterior teeth, (iv) absence of systemic or neurological temporomandibular disorder, and (v) cognitive skills that enabled the patient to answer the questionnaire used.These criteria were defined based on previous research that assessed the factors associated with mastication in patients with periodontal disease who had lost teeth 10 .
A periodontist examined the patients and selected a sample of 11 individuals based on convenience.The participants were informed of the objectives and ethical issues of the study, and all signed an informed consent form.This study was approved by the Ethics Committee of ULBRA (number 1007-434H).
All patients were treated by a periodontist based on a non-surgical periodontal approach.The following variables were assessed before the beginning of periodontal treatment and 30 days after the last session: (i) number of teeth (clinical examination), (ii) satisfaction and masticatory ability (using a questionnaire), and (iii) masticatory performance (based on the sifting of standardized chewable material morsels).The methods of evaluation are described in detail below.

Number of FTUs
The number of pairs of homonymous posterior occlusal teeth was evaluated counting posterior FTUs, when one pair of premolars is considered one FTU and one pair of molars represents two FTUs [16][17][18] .
Anterior teeth were classified using the same criterion, when one FTU was defined as a pair of homonymous occlusal anterior teeth.
Participants were instructed to chew 12 previously weighed Optocal cylindrical morsels carrying out 40 mastication cycles, with special care not to swallow any portion of the material.After mastication, the chewed material was collected in a beaker of known weight.Excess water was removed and the material was then dried in a stove at 80ºC for 1 h.The chewed material was weighed repeatedly upon constant weight (variation below 0.01 g).After, the material was transferred to a desiccator containing silica, which ensured complete humidity removal.
The chewed material was sifted in a shaker with five sieves of decreasing mesh size (4.75 mm, 4.00 mm, 2.80 mm, 2.00 mm, and 1.00 mm) 19 .The fractions retained in each sieve were weighed and expressed as percent fraction of the total material collected and dried.Based on these percent values, mean particle size was calculated as described in a previous study 19 .The sieving procedure was carried out twice for each sample, and mastication ability was calculated as the mean value of the two measurements.

Self-Reported Masticatory Ability and Satisfaction
Satisfaction and masticatory ability were measured using two questionnaires containing questions adapted from OHIP-EDENT 20 .Patients answered 10 questions about perception of satisfaction and 14 questions about their mastication ability in connection with their periodontal condition.Answers were recorded on a visual analogue scale (100 mm).One question about the overall evaluation of previous questions was included in each set of questions about satisfaction and ability.The values obtained were measured and converted in percent numbers for subsequent statistical analysis.The evaluations carried out using the questionnaires were supervised by the same observer, who clarified any doubts taking care not to interfere with answers.

Data Analysis
The correlation between the number of FTUs and satisfaction, ability, and performance scores was assessed using the Spearman correlation coefficient.Performance as well as self-reported masticatory ability and satisfaction before and after periodontal treatment were compared using the Wilcoxon and pairwise Student's t tests, respectively, at a 5% significance level.
362/364 RESULT All individuals presented the same number of FTUs before and after periodontal treatment.The mean numbers of anterior and posterior FTUs were 10.36 ± 1.43 and 6.73 ± 0.79, respectively.Mean numbers of FTUs were not correlated with satisfaction, ability, and performance before and after periodontal treatment (p > 0.05).Masticatory performance did not vary (p = 0.075), and mean particle sizes before and after periodontal treatment were 4.23 ± 1.84 mm and 3.90 ± 0.75 mm, in that order.
Table 1 shows the results of self-reported masticatory ability and satisfaction before and after periodontal treatment.In general, scores obtained after periodontal treatment were higher (p > 0.05) compared with those obtained before.Six of the nine questions used to evaluate satisfaction had higher scores after treatment, while the scores obtained for three did not vary.In addition, scores for two of the 13 questions about masticatory ability were better after treatment, while the scores for the other questions did not vary with periodontal intervention.

DISCUSSION
Although periodontal treatment did not influence objectively assessed masticatory performance, the intervention in partially dentate patients resulted in individuals expressing an improvement in self-reported satisfaction and masticatory ability.In addition, despite the fact that mean particle size of chewable material did not differ significantly after treatment, participants expressed higher satisfaction and felt more comfortable, self-assured, and less annoyed during mastication due to periodontal intervention.
The results of the present study confirm previously published findings, which underscored the positive effects of periodontal treatment and follow-up on mastication.A study that looked into the effect of loss of bone support due to periodontal disease on the masticatory apparatus demonstrated that the force produced by anterior teeth is negatively affected 15 .
In a study that evaluated bite force, masticatory pressure, and occlusal surface based on parameters like periodontal probe readings, levels of clinically evaluated insertion, gingival bleeding, and presence of crown caries, no relationship with masticatory ability was observed 9 .However, the number of teeth, gender, and diverse age groups of participants may have been an obstacle to proper assessment, since these variables interfere with the relationship between bite force and occlusal surface, reducing the values observed 9 .
Based on groups paired for age, gender, and number of teeth, Alkan et al. 10 studied the influence of these factors on mastication.The results showed that the decrease in periodontal support in absence of inflammation negatively affected masticatory ability (bite force and occlusal surface).The authors also declared that more studies should be conducted to analyze how severity of periodontitis affects mastication using larger sample populations.Takeuchi, Yamamoto 11 (2008) analyzed the correlation of periodontal status with bite force in patients with chronic periodontitis who had been treated and were at the follow-up stage.The results showed that clinically evaluated mean insertion values were more significant than the percent number of mobile teeth.The inferior bone support observed seemed to be associated with the decrease in bite force and the increase in bite pressure, which was defined by the authors as the force measured per square millimeter on the occlusal surface.
In the present study, despite the fact that masticatory performance measured using standardized chewable material did not improve with periodontal treatment, as a rule the participants expressed improved satisfaction and felt more able to masticate effectively.These results may be explained in view of the improvement in the inflammatory condition of teeth, which possibly exhibited reduced mobility, bleeding, and suppuration after intervention.Despite that, periodontal treatment improves quality of life of periodontal disease patients 21 .Moreover, the conservation of the number of FTUs during treatment added to the stabilization in the ability to masticate the chewable material.CONCLUSION

Table 1 .
Satisfaction and masticatory ability before and after periodontal treatment *Statistically significant difference between groups.