Comparison of the efficacy of different periodic periodontal scaling protocols for oral hygiene in adolescents with fixed orthodontic appliances: A prospective cohort study


The purpose of this reseach was to compare the effects of different periodic periodontal scaling protocols on the periodontal health of adolescents with fixed orthodontic appliances by assessing the aspartate aminotransferase (AST) and alkaline phosphatase (ALP) levels in gingival crevicular fluid and periodontal clinical indexes in a prospective cohort study.


Forty-eight adolescents were divided into 3 groups according to the interval of periodontal scaling (group A: once a month; group B: once every 3 months; group C: once every 6 months). The AST and ALP levels in the gingival crevicular fluid were measured before orthodontic treatment (T 0 ) and at 1 (T 1 ), 3 (T 2 ), 6 (T 3 ), and 9 (T 4 ) months during orthodontic treatment. Periodontal clinical indexes (plaque index [PI], gingival index [GI], and probing depth) were also assessed.


At T 2 , significantly lower AST and ALP levels were observed in group A than in groups B and C ( P <0.05). At T 3 and T 4 , lower AST and ALP levels were detected in groups A and B than in group C ( P <0.05), and there was no significant difference between the A and B groups at T 4 ( P >0.05). At T 2 , the PI and GI were increased in groups B and C compared with group A, and at T 3 and T 4 , significantly lower PI and GI values were observed in groups A and B than in group C ( P <0.05).


Periodontal scaling promotes the oral hygiene of adolescents undergoing fixed orthodontic treatment, and periodontal scaling protocols administered monthly and once every 3 months are better for controlling periodontal health than treatments administered once every 6 months.


  • Effect of periodontal scaling was studied in adolescent orthodontic patients.

  • Periodic scaling inhibited plaque accumulation and gingival inflammation.

  • Aspartate aminotransferase and alkaline phosphatase in gingival crevicular fluid were reduced.

  • Scaling performed monthly or every 3 months is more effective than every 6 months.

Fixed orthodontic appliances have been widely used in recent years because of their high efficacy. After the fixed appliances are bound, good oral hygiene is difficult to maintain because the brackets, bands and ligatures cover the teeth, resulting in plaque accumulation, bacterial reproduction, gingival swelling, bleeding and proliferation, particularly in adolescents. If the plaque around brackets is not controlled, attachment loss and alveolar bone resorption occur, that will influence tooth movement and orthodontic treatment efficacy. In addition, adolescents are unable to easily maintain good oral hygiene because of their poor compliance and relatively high hormone levels compared with adults. Therefore, methods to control the oral hygiene of adolescents with fixed appliances are very important and worthy of discussion.

Scholars have proposed a variety of preventive methods, such as oral health education, the use of power toothbrushes and periodontal scaling, to prevent periodontal inflammation caused by plaque accumulation during fixed orthodontic treatment. Oral health education has always been emphasized by orthodontists, and the cultivation of proper awareness of oral hygiene in adolescents with fixed orthodontic appliances is very important during orthodontic treatment. However, simple oral health education is sometimes ineffective due to the insufficient compliance and self-discipline of adolescents. According to the reports of Naranjo et al, a combination of periodontal scaling with oral health education effectively minimizes adverse stimulation of the periodontium by orthodontic appliances. For patients with gingivitis without orthodontic appliances, periodontal scaling every 6-12 months effectively maintains periodontal health. Few publications comparing the effects of different periodic periodontal scaling protocols on the periodontal health of adolescents with fixed orthodontic appliances are available.

Aspartate aminotransferase (AST) and alkaline phosphatase (ALP) have been recognized as gingival crevicular fluid (GCF) components that are closely related to periodontal inflammation. AST is a soluble cytoplasmic enzyme that is widely distributed throughout the human body. When the periodontium is destroyed and cells die, a large amount of AST is immediately released into the GCF to participate in the inflammatory process. In recent years, some studies have shown strong correlations between the AST level in the GCF and gingivitis and periodontitis; thus, AST levels represent a potential index for the diagnosis of periodontal diseases. ALP is a functional enzyme that is present in osteoblasts and is closely related to alveolar bone metabolism. The periodontal ligament contains a large amount of ALP, which can enter the GCF when the periodontium is destroyed and the permeability of periodontal ligament cells increases, thus increasing the ALP level. ALP is positively correlated with the periodontal pocket depth, attachment loss and bone destruction, which reflect the degree of inflammation and destruction in the early period of periodontitis. , According to the evidence described above, the periodontal lesions occurring in the early stage of orthodontic treatment may be reflected in the levels of AST and ALP in the GCF, and changes in AST and ALP levels may objectively and sensitively reflect the subtle changes in the periodontal tissue.

In our study, AST and ALP levels in the GCF and periodontal clinical indexes (plaque index [PI], gingival index [GI], and probing depth [PD]) were used to evaluate periodontal destruction in adolescents with fixed appliances, test the efficacy of different periodic periodontal scaling protocols and identify the optimal period to promote the oral hygiene of adolescents with fixed orthodontic treatment.

Material and methods

This prospective cohort study was approved by the Ethics Committee of the Affiliated Hospital of Qingdao University, Qingdao, China (#83-0117). All protocols performed in the present study were in accordance with ethical standards and were conducted in accordance with the Helsinki Declaration of 1975, as revised in 2008.

Fifty-four adolescents from the Department of Orthodontics of the Affiliated Hospital of Qingdao University between 2017 and 2018 were recruited in this study, including 27 males and 27 females aged 11 to 18 years. The sample size was calculated using G∗Power (version; Universität Düsseldorf, Kiel, Germany) statistical software based on a previous study, and 16 subjects per group were required to provide a statistical power of 80% at the 0.05 level. The inclusion criteria were as follows: patients with (1) no systemic diseases; (2) good oral hygiene compliance; (3) no obvious side-chewing habit; (4) no periodontal diseases, oral mucosal diseases, caries or fillings; (5) no treatment with antibiotics and hormones within 1 month before the experiments; and (6) <4 mm crowding without other severe malocclusion. Written informed consent was obtained from the parents of the adolescents, and the patients were randomly divided into 3 groups of 20 adolescents per group using sequentially numbered, opaque, sealed envelopes that were prepared before the study by a researcher (X.F) who was independent from the study. Every group underwent periodontal scaling at different intervals, as follows: once a month for group A, once every 3 months for group B, and once every 6 months for group C. The 2 researchers (J.C and T.X) were blinded to the grouping and were trained to collect samples and evaluate periodontal clinical indexes. All adolescents received oral hygiene education before the study, including “BASS” tooth brushing method, and the periodontal condition was monitored at every visit. Three participants didn’t attend visits on time and did not undergo periodontal scaling at the correct time interval. Finally, 48 participants were included in this study, with 16 adolescents in each group ( Fig ).

Consolidated standards of reporting trials (CONSORT) flow diagram of the patients.

Two professional orthodontists (C.J and C.F) with more than 10-years of clincial experience, performed the orthodontic treatment for the patients. After binding the metal nonself-ligating brackets (Victory Series; 3M Unitek, Monrovia, Calif), redundant adhesive was removed, and the arch wires were changed in sequence (0.014 nickel titanium (Niti), 0.016 Niti, 0.016 × 0.022 Niti, 0.019 × 0.025 Niti, 0.019 × 0.025 stainless steel). Metallic ligatures were used during the orthodontic treatment, and the frequency of appointments was 1 month. The patients were treated with periodontal scaling according to their respective cleaning cycles. Periodontal scaling was performed by the same periodontist (X.Y) by using an ultrasonic scaler and Gracey curettes to remove plaque, soft dirt, and dental calculus. The periodontal clinical parameters of the teeth (11, 26, 31, 44, or 45) were recorded, and GCF samples were collected before bracket bonding (T 0 ) and at 1 (T 1 ), 3 (T 2 ), 6 (T 3 ), and 9 (T 4 ) months of orthodontic treatment. If the first premolar of the right mandible was extracted, the second premolar of the right mandible was included. If periodontal scaling was needed, specimens were collected before periodontal scaling and after tooth brushing.

After washing the teeth with clean water and drying them, microcapillary pipettes were placed at designated sites (the center of the buccal side, the center of the lingual side, the mesial axial angle, and the distal axial angle) for 30 seconds, and 3μl of GCF was collected from each site. The pipettes were transferred to the laboratory immediately and frozen at −80°C for analysis. After thawing at room temperature, 200μl of phosphate buffer saline (potential of hydrogen = 7.6) was used to dissolve the gingival fluid and was centrifuged at 10,000 rpm/min for 10 minutes at 4°C. A total of 150μl of supernatant was evaluated in an automatic biochemical analyzer (7600-210; Hitachi, Tokyo, Japan), and AST and ALP levels were recorded.

The PI and GI were assessed according to the criteria reported by Çifter et al and the mesial buccal, middle buccal, distal buccal and lingual sides of the 4 teeth and the gingival condition were evaluated. For the assessment of the PD, the periodontal probe was inserted into the gingival sulcus along the axis of the teeth, and 6 loci (the mesial buccal, middle buccal, distal buccal, mesial lingual, middle lingual, and distal lingual) were recorded. The probing power was 20-25 g. All measurements were performed 3 times by the same examiner, with a 2-week interval between each assessment. The reproducibility of measurements was determined based on the intraclass correlation coefficients. The intraclass correlation coefficient showed high reliability, with r = 0.95.

Statistical analysis

Statistical analyses were performed using SPSS (version 19.0; SPSS, IBM Corp, Armonk, NY). Mean values and standard deviations were calculated, and paired t-tests were used to compare the differences among groups. P <0.05 was considered a statistically significant difference.


One month after bracket bonding (T 1 ), AST levels increased significantly in all 3 groups ( P <0.05), and after periodontal scaling, AST levels measured at T 2 , T 3, and T 4 decreased to the level before orthodontic treatment in group A, except for the AST level at tooth 26 ( P <0.05). In group B, the AST levels at teeth 11 and 44 decreased to the preorthodontic level at T 3 after the first periodontal scaling procedure, while the levels at teeth 26 and 13 decreased to the preorthodontic level at T 4 . In group C, the AST levels measured at any time point were higher than those measured at T 0 ( P <0.05), except for the level measured at tooth 11 at T 4 ( P >0.05). The AST levels measured at every tooth in different groups and the comparisons with T 0 are shown in Table I .

Table I
Comparisons of AST levels of different teeth between T 0 and other time points
Groups Time Maxillary right central incisor Maxillary left first molar Mandibular left central incisor Mandibular right first premolar
A Group T 0 409.17 ± 165.93 477.20 ± 172.33 453.03 ± 125.73 325.88 ± 156.55
T 1 608.00 ± 198.38 734.73 ± 178.51 685.51 ± 207.90 508.75 ± 210.72
T 2 514.45 ± 181.34 629.41 ± 267.24 564.70 ± 173.29 403.80 ± 179.05
T 3 483.13 ± 208.70 580.08 ± 207.64 546.73 ± 149.99 357.18 ± 155.88
T 4 454.69 ± 151.82 535.92 ± 177.68 454.06 ± 192.19 345.65 ± 168.22
B Group T 0 471.33 ± 313.79 483.69 ± 178.31 424.27 ± 147.89 393.82 ± 123.41
T 1 642.63 ± 250.03 675.80 ± 279.57 576.73 ± 176.00 528.95 ± 184.41
T 2 720.27 ± 207.34 838.67 ± 278.57 677.00 ± 181.93 518.87 ± 178.22
T 3 545.60 ± 196.62 639.87 ± 145.83 550.10 ± 164.09 423.54 ± 126.76
T 4 519.88 ± 221.40 584.74 ± 163.53 531.37 ± 170.90 359.96 ± 123.49
C Group T 0 452.87 ± 262.14 514.56 ± 185.88 495.93 ± 117.65 433.19 ± 134.25
T 1 696.73 ± 233.62 778.31 ± 22.97 656.29 ± 177.56 573.58 ± 217.18
T 2 657.20 ± 170.86 822.02 ± 213.15 736.91 ± 218.65 664.94 ± 203.28
T 3 681.07 ± 162.12 861.08 ± 175.65 712.73 ± 188.90 633.93 ± 169.71
T 4 572.79 ± 158.27 774.17 ± 164.09 606.29 ± 165.36 569.10 ± 176.01

T 0 , before orthodontic treatment; T 1 , 1 month after binding the brackets; T 2 , 3 months after binding the brackets; T 3 , 6 months after binding the brackets, T 4 , 9 months after binding the brackets.

P <0.05.

Table II shows the comparison of AST levels between different groups. The mean AST level of the 4 teeth is presented for each group and was used in the statistical analyses. A significant difference in AST levels was not observed between the different groups at T 0 and T 1 . At T 2 , a significantly lower AST level was observed in group A than in groups B and C ( P <0.05), while significant differences were not observed between groups B and C ( P >0.05). At T 3 and T 4 , lower AST levels were detected in groups A and B than in group C ( P <0.05), with no significant difference between groups A and B ( P >0.05).

Table II
Comparisons of AST levels between the groups
Time A group B group C group P A-B P A-C P B-C
T 0 416.32 ± 84.07 443.28 ± 9.74 474.14 ± 75.67 0.389 0.069 0.325
T 1 634.25 ± 93.82 606.03 ± 128.63 672.89 ± 93.89 0.473 0.327 0.094
T 2 528.09 ± 108.77 688.70 ± 138.31 720.27 ± 100.54 0.001 0.000 0.464
T 3 491.78 ± 90.28 539.78 ± 77.76 722.20 ± 75.64 0.114 0.000 0.000
T 4 447.58 ± 90.92 498.99 ± 75.35 630.59 ± 82.88 0.098 0.000 0.000
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Apr 19, 2021 | Posted by in Orthodontics | Comments Off on Comparison of the efficacy of different periodic periodontal scaling protocols for oral hygiene in adolescents with fixed orthodontic appliances: A prospective cohort study

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