In the current trial, the effectiveness of a single dose of the low-level laser before each stage of the orthodontic leveling and alignment treatment and paracetamol– caffeine combination drug in reliving the orthodontic pain were evaluated.
The current research work was a three-arm, parallel-design study. Some researchers have claimed that the split-mouth design is superior to the parallel design in the trials that evaluate patient-centered outcomes to overcome interpersonal differences such as sex, age, and psychiatric changes17. However, an inherent shortcoming of this design was the possibility of carrying the perception of pain from one side to another, resulting in difficulty in accurately determining pain by patients, especially after archwire replacement2,32. On the other hand, some studies did not find any relation between orthodontic pain perception and age or gender33.
Adult patients with mild to moderate upper and lower crowded arches were included in the current study. Adults can express their feelings more accurately than younger people34. The applied orthodontic force depends on the position of the teeth and the crowding level, especially after orthodontic separator placement or initial archwire engagement, as the greater force may cause greater pain2,35. Many previous studies did not consider the effect of crowding degree and the selected age group in their study designs21,22,25.
Similar to many previous studies2,4,7,18,21,22, a diode Ga-Al-As laser was used with a wavelength of 810 nm (near-infrared electromagnetic spectrum). Infrared radiation has a low absorption coefficient in hemoglobin and water; thus, more depth of penetration in the irradiated tissue, possibly reaching cortical and alveolar bone tissues4. To achieve the best results, it is important to use an appropriate amount of laser energy. In the current study, a power of 3.5 joules per point was applied, similar to the studies of Almallah et al., Owayda et al. after separators placement2,22 and studies of Qamruddin et al. and Domínguez et al. after archwires replacement4,28.
Due to the superiority of paracetamol-caffeine (500–65 mg) over acetaminophen alone12, and a greater level of safety when compared to other locally acting NSAIDs, it was chosen in the current trial as opposed to other investigations8,9 that solely used paracetamol for orthodontic pain management. Sandue et al. demonstrated that the effectiveness of analgesics depends on the drug’s pharmacokinetics in terms of dose and timing of administration36. To maintain a healthy drug plasma level in the current study, all patients were instructed to take their prescription an hour before any replacement and to continue taking a pill every 8 h for the first couple of days. Then, as needed, in the following days. This instruction was given as the orthodontic pain peaks after 24–48 h of force application2,21.
A small amount of spontaneous and chewing pain was perceived directly after each archwire replacement (a mean of 1 to 2 units on the NRS). The compression of the periodontal ligament fibers after orthodontic force application might be responsible for this immediate pain sensation2,23. This study showed that most patients experienced the most pain 24 to 48 h after undergoing orthodontic replacement, consistent with the results of many previous reports2,4,8,16,28. The time course of orthodontic pain may be related to biological changes after an orthodontic force is applied, specifically, the concentration of interleukin (IL) 1-beta that reaches its highest levels after 24 h37.
Intergroup findings
Differences less than 2 degrees on the Numeric Rating Scale (NRS) were considered not clinically significant. Understanding the minimally clinically important difference (MCID) is essential for evaluating the effectiveness of pain management modalities38.
The spontaneous and chewing pain levels induced by orthodontic separators were significantly lower than those from the drug and control groups, just at the peak of pain after 48 h of insertion. These results were similar to Almallah and Qamruddin et al.21,22. Qamruddin et al. used 940 nm of GaAlAs laser with 200 mW for 20 s and irradiated at three points: mesial, distal, and the middle of the first molar from the buccal side only. Almallah et al. compared single versus double laser irradiation doses with 4 J/cm2 energy applied for 28 s on each of the eight selected points (4 buccal and four palatal). Neither the LLLT nor the medication could relieve the orthodontic pain induced by orthodontic separators in the other assessment times. The current results contrasted what was reported by Mirhashemi et al. who evaluated double laser irradiations with 15 J/cm2 energy applied for 11 s on each point of cervical points for mesial and distal roots of the maxillary 1 st molar20. The difference in efficacy of LLLT may be due to variations in overall laser energy, application protocol, or study methodology, as suggested by Farzan et al.17. Similarly, the above results match the outcomes of Patel et al., who used only paracetamol one hour before and after 3 and 7 h of separator placement9. In contrast, Najafi et al. suggested that preemptive paracetamol alone could be an effective option for managing orthodontic pain; however, their study lacked a control group, and the results should be viewed with care8.
The pain levels experienced by the participants in the laser, drug, and control groups when the initial archwire (0.014 NITI) was installed were similar to those found in previous studies7,15. The 0.014 and 0.016 -NiTi-induced Pain mean scores in LLLT and paracetamol-caffeine groups were similar to those of the control group without significant differences. Conversely, Qamruddin et al. demonstrated that a single dose of Al-Ga-As laser irradiation with a power of 75 J per tooth can reduce the pain associated with the initial archwire4. The specific ability of LLLT to reduce the peak pain experienced after the separator placement, rather than after the installation of initial archwires, may be because separators induce significantly greater levels of pain than round archwires, leading to a greater concentration of inflammatory mediators, such as PGE2, IL-1β, and TNF. These mediators create a more suitable environment for laser irradiation to work effectively in reducing pain1. The study’s results indicate that the combination of paracetamol and caffeine did not provide significant relief for spontaneous and chewing pain caused by initial archwires, similar to what was observed with pain caused by separators. In a previous study by Alshammari et al., it was reported that using paracetamol or chewing gum after initial archwire installation had similar effects25. However, their study was limited by the absence of a control group, making it unclear whether the modalities used effectively controlled pain. This is particularly relevant to the current study, as pain mean scores in their study were compared to those of a control group in the current study.
The insertion of rectangular archwires caused mild levels of pain that peaked 24 h after insertion and subsided by the end of the week in all three study groups. The laser in the current study reduced pain levels during its peak at 24 and 48 h after rectangular wire insertion, but the amount of reduction was not clinically important. These results were similar to those reported by Dominguez and Velasquez, who evaluated the effect of a low-energy GaAlAs laser with a wavelength of 830 nm and an energy of 100 J/cm2 for 22 s on the vestibular and palatal/lingual sides after 0.019*0.025 SS archwire insertion in crowded cases that were resolved without extraction28. This effect may be attributed to the cumulative effect of successive laser doses applied from the first to the final stage in this study. In the drug group, the mean values of the spontaneous and chewing pain scores after 24 and 48 h of placing the 0.016*0.022 NiTi and 0.019*0.025 NiTi archwires were the lowest among the tested groups. However, the multiple comparisons did not reveal any statistically significant differences between the drug and control groups. The medication used was not effective in alleviating mild pain levels in stages from 0.016*0.022 NITI to 19*25 SS, and this may be attributed to the fact that the pain levels induced in these stages were mild; there was no need to relieve these mild pain levels, and this psychological factor may have affected the drug’s efficacy.
The drug intake did not significantly reduce pain levels compared to receiving no treatment, although there was some decrease. Additionally, the addition of caffeine did not appear to enhance the pain-relieving effect of paracetamol on induced pain.
Within group findings
Most previous studies in this area have only examined one stage, either separators2,8,21,22 or the initial archwire4,7,15,25, as the source of force. We believe that studies focusing on a single component as the source of force may draw inaccurate conclusions because the nature of pain caused by each stage may have different characteristics compared to the pain caused by other stages. Therefore, to the limit of our knowledge, this study is the first to assess all stages of leveling and alignment treatment with a fixed appliance, providing a comprehensive understanding of orthodontic pain from A to Z.
In the current study, pain levels (spontaneous and chewing) were significantly greater in the separation and initial archwire stages compared to other stages after 24 and 48 h in the laser, drug, and control groups. However, there was no significant difference between these two stages. It is commonly believed that orthodontic pain increases proportionately to the force applied, which may explain why there was more intense pain during initial archwire alignment but decreased with the 0.016-in wire and became almost non-existent later on4. This also could be attributed to the patient’s exposure to new procedures that could increase anxiety and pain levels39. Additionally, patients may become accustomed to the fixed appliance and the pain it causes over time, although there is currently no research to support this theory.
Specifically, the pain levels during separation were slightly greater than those induced by the 0.014 NiTi archwire. This could be interrupted by the fact that the pain caused by the separator differs from that caused by the archwire, as the separator exerts only lateral forces for teeth separation. In contrast, fixed orthodontic treatment using an archwire involves more complex movements, such as extrusion, intrusion, and uncontrolled tipping, which can contribute to a different type of pain7.
Additionally, no significant differences were detected between the pain mean scores recorded for the initial archwire and 0.016*0.022 NiTi or 0.019*0.025 NiTi. One possible explanation is that the 0.016*0.022 NiTi archwire is the first rectangular archwire that transfers torque data, and the 0.019*0.025 NiTi wire is the largest wire that conveys the majority of torque data through the brackets40. Orthodontic pain can be a significant concern following the initial stages of orthodontic treatment, particularly after the placement of separators and the initial archwire installation. However, using buccal tubes can help avoid the need for separators.
Limitations
One of the limitations of the current study was that masking was not applicable due to the long-term follow-up period and patients in the control group did not receive any placebo procedure, and the placebo procedures could play an intervention role in pain studies. Additionally, the current study did not assess participants’ pain threshold before enrollment. no drop-outs were planned during sample calculation of this trial. Another limitation of the current study is that the use of medication in the drug group after the first couple of days of treatment was not tracked or analyzed through subgroup or sensitivity analysis.