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Table of Contents   
ORIGINAL RESEARCH  
Year : 2019  |  Volume : 30  |  Issue : 4  |  Page : 527-530
Salivary flow rate, pH and buffering capacity in patients undergoing fixed orthodontic treatment – A prospective study


1 Department of Public Health Dentistry, Sathyabama Dental College and Hospital, Chennai, Tamil Nadu, India
2 Department of Public Health Dentistry, Ragas Dental College and Hospital, Chennai, Tamil Nadu, India
3 Department of Public Health Dentistry, Rajarajeswari Dental College, Bengaluru, Karnataka, India

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Date of Submission04-Feb-2016
Date of Decision02-Oct-2018
Date of Acceptance31-Oct-2018
Date of Web Publication18-Nov-2019
 

   Abstract 

Background: Human saliva has got many important functions like lubrication of the oral tissues, making oral functions like speech, mastication and deglutition possible and also protecting teeth and oral mucosal surfaces in different ways. Dental Caries is one of the common complications in patients undergoing orthodontic treatment. Subjects with impaired saliva flow rate often show high caries incidence. A low flow rate combined with a low or moderate buffer effect clearly indicates poor salivary resistance against microbial attack. Aim: To investigate the changes in stimulated and unstimulated salivary flow rate, pH and buffer capacity in patients undergoing therapy with fixed orthodontic appliances. Materials and Methods: Salivary flow rate, pH and buffering capacity of 20 patients who underwent fixed orthodontic treatment at Department of Orthodontics, Ragas Dental College and Hospital, Chennai were examined using GC saliva check buffer kit. The procedure was carried out during the initiation of orthodontic treatment and subsequently, one month and six months after the placement of appliance. Results: Results showed there was a significant increase in the salivary flow rate one month and six months after placement of fixed appliance while pH and buffering capacity showed no significant changes. Conclusion: Salivary flow rate increases significantly during fixed orthodontic treatment. Salivary pH and buffering capacity showed no significant changes suggesting that they are not sole factors for demineralization in orthodontic patients.

Keywords: Buffer capacity, fixed orthodontic appliance, flow rate, pH, saliva

How to cite this article:
Anu V, Madan Kumar P D, Shivakumar M. Salivary flow rate, pH and buffering capacity in patients undergoing fixed orthodontic treatment – A prospective study. Indian J Dent Res 2019;30:527-30

How to cite this URL:
Anu V, Madan Kumar P D, Shivakumar M. Salivary flow rate, pH and buffering capacity in patients undergoing fixed orthodontic treatment – A prospective study. Indian J Dent Res [serial online] 2019 [cited 2019 Dec 15];30:527-30. Available from: http://www.ijdr.in/text.asp?2019/30/4/527/271160

   Introduction Top


Saliva promotes good oral health. Human saliva has got many important functions like lubrication of the oral tissues, making oral functions like speech, mastication and deglutition possible and also protecting teeth and oral mucosal surfaces in different ways. The lubricating and antimicrobial functions of saliva are maintained mainly by resting saliva. Stimulation of salivary flow results in a flushing effect and the clearance of oral debris and noxious agents.

The quality and the quantity of saliva plays an important role in the oral equilibrium.[1] Specific changes, such as increased pH, buffer capacity and flow rate, may contribute to decreased susceptibility to dental caries.[2],[3] Reduced salivary flow rate and the associated reduction of oral defense systems may cause severe caries and mucosal inflammations. Patients undergoing treatment with fixed orthodontic appliances are suspected to be risk for dental diseases.[4],[5] Salivary properties is extremely important during treatment with fixed orthodontic treatment, when an increased chance of plaque retention and a greater difficulty in optimal oral hygiene maintenance are thought to predispose to enamel demineralization and white spot formation.[5],[6] There is still no agreement on the way the quality and the quantity of saliva change during orthodontic treatment.[7]

Orthodontic brackets presence makes teeth cleaning more difficult, and predisposes to plaque accumulation on the tooth surface and the gingival margin. In addition, fixed appliances may restrict the ability of the tongue to remove food particles from the mouth. Insertion of fixed orthodontic appliances creates stagnation areas. An increase in flow rate promotes the physical cleansing action of saliva, increases its buffering capacity and anti-bacterial activities, and accelerates clearance of substrates. For this reason, assessment of flow rate and other salivary parameters are recognized as important elements for the diagnosis and management of severe demineralization and acute caries. The irregular surface of brackets and bands reduces access by saliva, encouraging a lowering of plaque pH in the presence of carbohydrates. Studies have shown an increased rate of demineralization among patients undergoing fixed orthodontic therapy.[8],[9] Very few studies have been carried out to find out salivary flow rate, pH and buffering capacity of saliva among the patients undergoing fixed orthodontic therapy in India. The aim of this study is to investigate the changes in stimulated and unstimulated salivary flow rate, pH and buffer capacity in patients undergoing therapy with fixed orthodontic appliances.


   Materials and Methods Top


The present pilot study was carried out after obtaining clearance from the Institutional Review Board/Ethical Committee of Ragas Dental College and Hospital, Chennai. 20 patients who underwent fixed orthodontic treatment in the Department of Orthodontics, Ragas Dental College and Hospital, Chennai were randomly selected and examined after obtaining informed consent from the patient/parent/guardian. Patient who are healthy and who had no dental diseases were included. Patients with chronic systemic illness, on any long term oral medication, who are undergoing chemotherapy or radiotherapy for cancer treatment, with recent use of antibiotics and who are not interested to participate in the study were excluded.

The procedure was carried out before starting orthodontic treatment and subsequently, one month and six months after the placement of appliance. Salivary samples were taken between 9 am and 12 pm, at least 2 hours after meals and oral hygiene procedures in order to minimize the effects of diurnal variability in salivary composition.[4]

Before placement of the orthodontic appliance the patients underwent oral Prophylaxis in the Department of Periodontia. The appliance was placed by the orthodontic professionals from the Department of Orthodontia, Ragas Dental College and Hospital, Chennai. All patients selected were treated with a straight wire technique using MBT 0.022-inch-slot brackets (American Orthodontics, India Pvt Ltd) on both the maxillary and the mandibular arches. Oral hygiene instructions were given after placement of the fixed orthodontic appliance, followed by proper reinforcement at regular intervals when patient visits for appliance adjustments.

The saliva sample was collected and analysed for stimulated and unstimulated salivary flow rate, pH and buffer capacity of saliva using GC saliva check buffer kit (GC Corp., Tokyo, Japan).[4],[8]

Measuring the salivary flow rate

The unstimulated saliva was collected 2 hours after having the breakfast with instructions not to have anything in between. The patients were first asked to wash their mouth thoroughly with plain water. The patients were asked to sit up relaxed with their mouth open and head bent down and then asked to expectorate all resting saliva from their mouth into a small disposable cup every minute for 5 minutes and then the flow was calculated in terms of ml/min using a graduated test tube.

The next step is testing the pH of the sample of resting saliva in the disposable cup

This was done by dipping pH paper directly into the sample of oral fluid to wet it and then removing it immediately. The paper was not allowed to dry before scoring it as this can affect the visual interpretation of the colour. The colour change on the pH paper was matched with the standard colour scale on the chart and then assigned the exact pH value.

Test to estimate buffer capacity

A small 2 ml disposable pipette was used to withdraw a small quantity of saliva from the disposable cup which is then dispensed as one drop onto each of the three test pads of the buffer strip. Sufficient saliva was placed in order to wet the test pad fully. Excess saliva was blotted away by turning the strip 90 degree on the absorbant tissue. The test pads changed colour immediately and after 5 minutes the final results was matched with the standard colour scale on the chart. Each pad that scored green was given four points, a partial green/blue result 3 points, blue 2 points, blue/red partial transitions 1 point and red pad 0 point. In this way a 12 point scale is created from which later changes in buffer capacity was estimated.

The procedure was carried out before starting orthodontic treatment and subsequently, one month and six months after the placement of appliance.

Statistical analysis

The data was entered in Windows Excel 2007 and the statistics was analysed using SPSS version 16. Friedman test was used to investigate the presence of variance in the stimulated and unstimulated salivary flow rate, pH and buffer capacity during the orthodontic appliance treatment period (Baseline/Initial Stage, first month and sixth months after the placement of appliance).

After the existence of variance among the group was confirmed in the Friedman test, Wilcoxon signed-rank test was applied to understand how significantly each group (Baseline/Initial Stage, first month and sixth month after the placement of appliance) differs from other. The level of significance was set as 0.05.


   Results Top


[Figure 1] shows that there is a statistically significant change in the unstimulated salivary flow rate during the orthodontic treatment period. This is evidenced by the Friedman test statistic χ2 (2) = 30.632, P = 0.003. From the Wilcoxon signed rank test, we can confirm that unstimulated salivary flow rate has changed significantly from the first month of the Orthodontic treatment.
Figure 1: Distribution of study population based on unstimulated salivary flow rate. Friedman test statistic χ2 (2) = 30.632, P = 0.003. Wilcoxon signed rank test (baseline to 1st month) Z = −3.557, P = 0.000. Wilcoxon signed rank test (1st month to 6th month) Z = −2.236, P = 0.025

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[Figure 2] shows statistical significant change in the stimulated salivary flow rate during orthodontic period. This is evidenced by the Friedman test statistic χ2 (2) = 12.000, P = 0.002. From the Wilcoxon signed rank test, it is evidenced that stimulated salivary flow rate has not changed significantly in the first month of the Orthodontic treatment (Z = -1.941. P = 0.052). However, the stimulated salivary flow rate has significantly changed in the sixth month of the treatment (Z = -2.972, P = 0.003).
Figure 2: Distribution of study population based on stimulated flow rate. Friedman test statistic χ2 (2) = 12.000, P = 0.002. Wilcoxon signed rank test (baseline to 1st month) Z= −1.941. P =0.052. Wilcoxon signed rank test (1st month to 6th month) Z = −2.972, P = 0.003

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[Figure 3] and [Figure 4] shows that there is no significant difference between pH and buffer capacity during orthodontic treatment. Friedman test statistic shows χ2 (2) = 4.429, P = 0.109 and χ2 (2) = 3.818, P = 0.148 for pH and buffering capacity of saliva respectively.
Figure 3: Distribution of study population based on salivary pH. Friedman test statistic χ2 (2) = 4.429, P = 0.109

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Figure 4: Distribution of study population based on salivary buffer capacity. Fried test statistic χ2 (2) = 3.818, P = 0.148

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   Discussion Top


Fixed orthodontic appliances are devices or equipments that are attached to the teeth, cannot be removed by the patient and are capable of causing tooth movement. These appliances are found to induce plaque retention and thereby constituting risk for white spot enamel lesion. Favorable changes in the salivary parameters such as stimulated and unstimulated salivary flowrate, pH and buffering capacity might help in maintaining the oral equilibrium. With this consideration, the present study was undertaken. The salivary parameters were estimated using GC saliva check buffer kit (GC Corp. Tokyo, Japan).[4],[8]

Results from this study showed that there is an increase in the salivary flow rate with no significant changes in salivary pH and salivary buffer after placement of fixed orthodontic appliance. The stimulated and unstimulated salivary flow rate were found to be increased in first and six months after band placement when compared to the baseline. This was in accordance with the study done by Kanaya et al., (2005),[10] Kanaya et al., (2007)[11] Chang et al., (1999).[12] An increase in the stimulated and unstimulated salivary flow rate might be related to the presence of appliance which appears to act as a mechanical stimulus in the salivary reflexes. Increase in salivary flowrate can have a protective effect in preventing dental caries.[10],[11]

The pH and buffer capacity clinically showed no significant statistical change. Increased salivary flow is followed by increased pH [13] and buffer capacity,[9],[14] but some authors have also reported a decrease in buffer capacity.[15] The present study is in accordance with the study done by Ulukapi et al.[16] and Peros et al.,[7] who found a significant increase in salivary flow rate and no significant change in buffer capacity, which suggests that salivary flow rate is more sensitive to the placement of orthodontic appliances than buffer capacity.

Insignificant pH and buffering capacity of saliva after placement of fixed orthodontic appliances suggests that they are not the sole factor increasing the patient's caries risk during orthodontic treatment. There can be other factors like, orthodontic adhesive remaining around the bracket base whose rough adhesive surface provides an ideal site for rapid attachment and growth of oral microorganisms.[17],[18] Lack of oral hygiene and improper brushing technique during orthodontic treatment can also be a contributing factor for demineralization.

Although the study was followed up for 6 months after placing orthodontic appliance, the saliva might show changes over longer treatment periods. Restricting the study for 6 months with smaller sample size is the major limitation of this study. Future studies to assess saliva during entire treatment period might help in understanding the salivary changes induced by the placement of orthodontic appliance. However, from this study it can be recommended that saliva should be considered during orthodontic treatment planning because the composition, pH, and flow rate of saliva might influence bacterial adherence to enamel and orthodontic surfaces.


   Conclusion Top


An increase in caries-promoting bacteria and plaque during orthodontic treatment will promote demineralization. On the other hand, resting salivary flow rate increases during fixed appliance therapy. The clinical significance of this study is that there is a significant increase in the salivary flow rate during orthodontic treatment which is suspected to be due to the mechanosensation of the fixed orthodontic appliance. Insignificant pH and buffering capacity suggests that they are not sole factor for demineralization in orthodontic patients.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

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Leone CW, Oppenheim FG. Physical and chemical aspects of saliva as indicators of risk for dental caries in humans. J Dent Educ 2001;65:1054-62.  Back to cited text no. 1
    
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Bardow A, Nyvad B, Nauntofte B. Relationships between medication intake, complaints of dry mouth, salivary flow rate and composition, and the rate of tooth demineralization in situ. Arch Oral Biol 2001;46:413-23.  Back to cited text no. 3
    
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Varma S, Banerjee A, Bartlett D. An in vivo investigation of associations between saliva properties, caries prevalence and potential lesion activity in an adult UK population. J Dent 2008;36:294-9.  Back to cited text no. 4
    
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Bollen AM, Cunha-Cruz J, Bakko DW, Huang GJ, Hujoel PP. The effects of orthodontic therapy on periodontal health: A systematic review of controlled evidence. J Am Dent Assoc 2008;139:413-22.  Back to cited text no. 5
    
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7.
Peros K, Mestrovic S, Anic-Milosevic S, Slaj M. Salivary microbial and nonmicrobial parameters in children with fixed orthodontic appliances. Angle Orthod 2011;81:901-6.  Back to cited text no. 7
    
8.
Alessandri Bonetti G, Incerti Parenti S, Garulli G, Gatto MR, Checchi L. Effect of fixed orthodontic appliances on salivary properties. Prog Orthod 2013;14:13.  Back to cited text no. 8
    
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Yun-Wah LP, Wing-Kit WR. Risks and complications in orthodontic treatment. Hong Kong Dent J 2006;3:15-22.  Back to cited text no. 9
    
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Kanaya T, Kaneko N, Amaike C, Fukushima M, Morita S, Miyazaki H, et al. The effect of orthodontic appliances on levels of Streptococcus mutans, Streptococcus sobrinus and microbial flora in saliva. Int Congr Ser 2005;1284:189-90.  Back to cited text no. 10
    
11.
Kanaya T, Kaneko N, Amaike C, Fukushima M, Morita S, Miyazaki H, et al. A study on changes in caries risk and microbial flora with the placement of edgewise appliance. Orthodontic Waves 2007;66:27-32.  Back to cited text no. 11
    
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Chang HS, Walsh LJ, Freer TJ. The effect of orthodontic treatment on salivary flow, pH, buffer capacity, and levels of mutans streptococci and lactobacilli. Aust Orthod J 1999;15:229-34.  Back to cited text no. 12
    
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Wu KP, Ke JY, Chung CY, Chen CL, Hwang TL, Chou MY, et al. Relationship between unstimulated salivary flow rate and saliva composition of healthy children in Taiwan. Chang Gung Med J 2008;31:281-6.  Back to cited text no. 13
    
14.
Diaz de Guillory C, Schoolfi eld JD, Johnson D, Yeh CK, Chen S, Cappelli DP, et al. Co-relationships between glandular salivary flow rates and dental caries. Gerodontology 2014;31:210-9.  Back to cited text no. 14
    
15.
Heintze U, Birkhed D, Björn H. Secretion rate and buffer effect of resting and stimulated whole saliva as a function of age and sex. Swed Dent J 1983;7:227-38.  Back to cited text no. 15
    
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Ulukapi H, Koray F, Efes B. Monitoring the caries risk of orthodontic patients. Quintessence Int 1997;28:27-9.  Back to cited text no. 16
    
17.
Ortendahl T, Thilander B, Svanberg M. Mutans streptococci and incipient caries adjacent to glass ionomer cement or resin-based composite in orthodontics. Am J Orthod Dentofacial Orthop 1997;112:271-4.  Back to cited text no. 17
    
18.
Ogaard B, Rølla G, Arends J. Orthodontic appliances and enamel demineralization. Part 1. Lesion development. Am J Orthod Dentofacial Orthop 1988;94:68-73  Back to cited text no. 18
    

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Correspondence Address:
Dr. V Anu
Department of Public Health Dentistry, Sathyabama Dental College and Hospital, Jeppiar Nagar, OMR, Chennai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdr.IJDR_74_16

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