Effectiveness of kinesio taping on postoperative morbidity after impacted mandibular third molar surgery: a prospective, randomized, placebo-controlled clinical study

Abstract Objective Our study seeks to investigate the effectiveness of kinesio taping (KT) on postoperative morbidity compared to placebo and control groups after impacted third molar surgery. Methodology Sixty patients with impacted mandibular third molar were included in this prospective, randomized, placebo-controlled clinical study. After surgical extraction of the impacted tooth, patients were allocated into three groups (20 patients each): group 1 received KT (kinesio), group 2 received placebo taping (placebo), and group 3 received no taping (control). The groups were compared regarding facial swelling, pain and trismus. Swelling was evaluated using a tape measuring method. Pain was assessed by a visual analog scale and the number of analgesic tablets taken. Trismus was determined by measuring maximum mouth opening. Results In the KT group, all parameters reduced significantly on 2nd and 4th postoperative days compared to other groups; however, placebo and control groups revealed comparable outcomes. On 7th day, all groups showed comparable results. Conclusions The KT application is an effective method for reducing morbidity after impacted mandibular third molar surgery. However, placebo taping is not as effective as proper taping. Placebo taping shows similar results compared to no taping regarding facial swelling percentage, pain and trismus.


Introduction
Surgical extraction of impacted third molar teeth is one of the most frequent operations in the field of oral and maxillofacial surgery (OMS), worldwide. Similar to other oral surgical procedures, patients suffer from a number of discomforts and disabilities (swelling, pain, and trismus ongoing seven to ten days after surgery). These morbidities are due to inflammatory response in consequence of surgical trauma. The postsurgical morbidities affecting jaws and face cause significant discomfort to patients. In attempt to reduce inflammatory response associated with surgical trauma and postoperative morbidity after OMS, many adjuvant applications including different surgical techniques, 1 drugs, 2,3 drains, 4,5 low-level-laser therapy, 6,7 cooling therapy 8 or physical therapy 9 have been reported.
Drug-related adverse effects, complications and contraindications led researchers to study non-drug methods. One of the adjuvant applications to reduce morbidity after traumatic injuries in sports medicine is kinesio taping (KT), which was introduced as an elastic therapeutic taping technique in 1970s. 10 The KT technique implements its effect on lymphatic drainage by lifting the skin, thus guiding lymph flow to move from higher to lower pressure sites. [11][12][13] Based on this physiologic principle, KT removes congestions of lymphatic fluids and hemorrhages. 11,12 Taping can also affect mechanoreceptors of joints and muscles, decreasing the nociceptive pain. 13 On the other hand, a recent meta-analysis concluded that the use of kinesio taping in musculoskeletal disorders had insufficient evidence. 14 However, despite the vast clinical experience, evidence-based scientific publications on the effectiveness of KT technique in the field of OMS are scarce. Recent studies evaluated the effects of KT technique after OMS procedures including impacted tooth surgery, maxillofacial trauma and orthognathic surgery. 5,[15][16][17][18][19][20][21]  The patients that met the inclusion criteria were randomly assigned to one of the three study groups

Kinesio Taping
Kinesio taping was performed just after the surgery. All taping procedures were performed by the same KT certified physician according to the lymphatic correction technique described by Kase, et al. 10 (2003) Kinesio ® Tex Gold TM was used as KT material. Before the application, patient's skin was cleaned, and moistureand oil-free condition was provided. The lymphatic correction technique was used to remove the edema.
The taping material was cut into five pieces equal in width, leaving 1.5-2.0 cm uncut tape at the base.
The base of the five-strip taping material was applied slightly above the supraclavicular lymph node without tension. The strips were then directed at the lymphatic duct and applied one by one with slight tension (15% of available) ( Figure 1). One I-shaped kinesio strip was used for placebo taping. The strip was applied parallel to the axis of the corpus mandible. No tension was applied to the taping material. Tapes remained for 5 days.

Data Collection
All measurements were performed by the same researcher. The surgery time was recorded for each patient as the time elapsed between initial incision and final suturing. Measurements and data collections were performed at four specific time points: baseline, 2 nd , 4 th , and 7 th postoperative days.
To evaluate trismus, maximum mouth opening (MMO) was recorded using calipers. The MMO was measured between the edges of upper and lower central incisors in millimeters.

Statistical Analysis
The statistical analysis was performed using SPSS software (SPSS 17.0; Chicago, IL, USA). Descriptive analyses and chi-squared test were used to compare participants' baseline characteristics. One-way ANOVA was used to test differences among the groups at the same time interval. Bonferroni-corrected post-hoc tests were used for multiple comparisons. The level of significance was set at p<0.05.

Baseline Characteristics
In total, 60 patients that met the inclusion criteria were enrolled in the study and randomly allocated to one of the three study groups (20 patients in each).
Our study was conducted without droppouts. The baseline characteristics of the groups, including age, gender, and operation time, are shown in Table 1.
There were no differences among the groups regarding of baseline characteristics (p>0.05; the exact p-values are shown in Table 1). No complications were evident during study. During the postoperative 2 nd and 4 th days, significant differences were observed among the groups (all p<0.001; the exact p-values were shown in Table 2).

Comparison of Pain Measurements
During the postoperative 2 nd and 4 th day follow-up visits, significant differences were observed in pain VAS scores among the groups (Table 3, all p<0.001).
After multiple comparisons, we found that pain values in KT group were significantly lower than in placebo and control groups on the postoperative 2 nd and 4 th days (the exact p-values are shown in Table 3). During the postoperative 7 th day follow-up visit, all groups showed comparable pain values in both resting and chewing states ( Table 3). The patients of KT group took significantly less analgesic tablets than patients of placebo and control groups at all follow-up visits (Table 3). Regarding pain VAS scores and number of analgesic tablets, placebo and control groups revealed comparable outcomes in all follow-up visits.

Comparison of Trismus Measurements
The baseline MMO values were comparable in the three groups (p=0.780) ( p*, p-value for the comparison among groups (one-way ANOVA) p1-2, p-value for multiple comparison of kinesio and placebo groups (Bonferroni-corrected post-hoc test) p1-3, p-value for multiple comparison of kinesio and control groups (Bonferroni-corrected post-hoc test) p2-3, p-value for multiple comparison of placebo and control groups (Bonferroni-corrected post-hoc test)  four studies after impacted tooth surgery, 5,15,16,18 two studies after orthognathic surgery, 20,21 and one study for temporomandibular joint disorders. 23 However, the aforementioned studies did not include placebo taping.
Thus, the actual efficacy of KT application, distinguished from the placebo effects, on postoperative morbidity after OMS is not clear in the literature. Ristow, et al. 19 (2014) revealed that KT application significantly reduced swelling but were not effective against pain and trismus control after surgical treatment of zygomatico-orbital fractures. In another study, Ristow, et al. 17 (2013) reported that KT did not significantly reduce postoperative trismus and pain after surgical treatment of mandibular fractures. Likewise, Tozzi, et al. 20 (2016) reported that KT had a significant effect on reduction of facial swelling but no effect on pain and trismus reduction after orthognathic surgery. These studies did not contain placebo group. Thus, the aforementioned insignificant effects of KT on pain and trismus control might be due to the placebo effects pooled in the kinesio group. Ristow, et al. 18 (2014)   For description of p-values, please see footnote of Table 2. al. 15 (2020) concluded that KT was effective in reducing edema and pain after impacted third molar surgery. A recent split-mouth clinical study by Gözlüklü,et al. 16 (2020) reported that their newly described KT method was more effective when compared with classic KT method in reducing postoperative morbidity after impacted third molar surgery. Genc, et al. 5  Patients' baseline characteristics in all groups were comparable. Thus, the differences among the groups can be attributed to the efficacy of KT application.
Our study showed that KT application significantly reduced postoperative morbidity (swelling, pain and trismus) on days 2 and 4 after impacted tooth surgery.
The effectiveness of KT ended on 7 th postoperative day. Our study also contained placebo and control groups that did not show similar significant effects when compared with the kinesio group. Thus, we can conclude with confidence that our hypothesis was mostly confirmed.
Some factors affect the effectiveness of KT, such as tape thickness, adhesion and stretch capacity, and correct application technique. 12 The KT can stretch up to 1.4 fold of its original length, and recoils back to its original length during the following days. For proper KT application, the head of the patient should be rotated and the muscles should be extended in order to stretch the skin before taping. When head of the patient returns to its resting position, the elastic band subsequently recoils back and forms convolutions on the taped skin. When the taping technique is correctly applied, the tape pulls the skin and increases the interstitial space between the skin and connective tissue, thus promoting the hemorrhagic and lymphatic drainage. 12 Since KT is thought to improve the blood and lymph flow, it has become a popular method in the management of lymphedema. 11 In our study, we observed that in addition to decreasing swelling, KT reduced trismus and pain, possibly due to decreased lymphedema and skin tension. However, these effects were not seen in placebo group (taping without tension). Considering favorable effects of KT on pain and trismus, our results were different from previous studies, 17,19,20 in which KT was reported to be ineffective on pain and trismus control. In consistence with previous investigations, 17-19 the KT was removed on the 5 th postoperative day in our study. However, Genc, et al. 5 (2019) reported that the tape was removed on the 2 nd postoperative day. The application time of the therapeutic tape might also influence KT effectiveness.
In our study, the methods for swelling, pain and trismus measurement were precise, simple, inexpensive, and of easy approach, also being reported in many previous studies. 1,5,15,[17][18][19]21 The 3-D assessment of postoperative facial swelling was reported as a novel and accurate method in recent studies. 8,16,20,26 However, this method has not yet been considered easy, practical, cheap, and widely available.
One of the novel aspects of our study was that the effectiveness of KT on facial swelling was reported by each line measurement separately as well as mean sum values. In all of the previous studies, 5,[17][18][19]21 facial swelling was reported only by mean sum of all One of the limitations of our study was that it was not a split-mouth study. Different patients were assigned into three different study groups. A splitmouth study design might provide better evidence level. However, patients' baseline characteristics, including age, gender, and operation time distribution, showed comparable results. Another limitation might be that swelling was not assessed with 3D methods, which could provide volume comparison. However, tape measuring method used to assess swelling in our study was frequently used in previous studies and reported to be reliable. 5,15,[17][18][19]21 Thus, we could compare our results with previous similar studies.
Although absent in our study, taping-related complications such as irritation or allergic reactions on skin should be considered. Thus, patients should be informed about possible adverse reactions before taping, especially those with sensitive skin.

Conclusion
The KT application is an effective method for reducing postoperative morbidity (swelling, pain, and trismus) after impacted mandibular third molar surgery. However, placebo taping is not as effective as proper taping. Placebo taping shows similar results compared to no taping regarding facial swelling percentage, pain, and trismus.

Conflict of interest disclosures
None of the authors reported any disclosures.