Adjunctive therapies in orthodontics: a scoping systematic review | BMC Oral Health

Effect of adjunct therapies on clinical parameters during teeth alignment

Low-level laser therapy

This review synthesized data from 11 randomized clinical studies [26,27,28,29,30,31,32,33,34,35,36], conducted in several countries, thereby providing an inclusive analysis of the effects of LLLT on fixed orthodontic treatment outcomes, Table 1.

The studies encompassed a diverse demographic of 296 patients of both genders, aged 10 to 40, involving cases and controls ranging from 10 to 94 participants. Orthodontic treatments primarily involve fixed appliances, with some studies using specific configurations such as split-mouth designs, Table 1.

The primary focus is fixed orthodontic treatments, with a detailed examination of low-level laser therapy applications using different Semiconductor Diode Lasers. These lasers operate at wavelengths ranging from 780 to 970 nm, with application durations varying from 2 s to 5 min per point or per tooth, thereby highlighting the significant diversity in laser application protocols, Table 1.

The methodology for laser application varied significantly among the studies. Energy dosage and application frequency for laser irradiation delivery also varied, with some studies applying laser at multiple time points throughout the treatment, ranging from the initial day of retraction up to monthly intervals, to enhance the rate of tooth movement. The points of application included buccal, lingual, cervical, middle, and apical regions of the teeth, particularly focusing on canine roots and maxillary incisors. The clinical assessments typically focused on measures of tooth movement, such as space closure and canine retraction, with evaluations performed at multiple time points throughout the treatment, presented in Table 1.

Clinical assessments were primarily based on digital scans and study casts to evaluate specific outcomes such as maxillary canine retraction and space closure, canine rotation, and the efficiency of de-crowding maxillary anterior teeth. The outcome measures across the studies indicated varying degrees of effectiveness of LLLT in accelerating orthodontic tooth movement, reducing treatment duration, and improving leveling and alignment. Some studies reported significant improvements in tooth movement acceleration [26, 27, 29,30,31, 33,34,35,36], while others found no significant differences when comparing the laser-treated groups and untreated controls [28, 32].

Additionally, some of the reviewed studies [28, 32], employed a split-mouth design to simultaneously compare experimental and control treatments within individual subjects. This method effectively minimizes inter-subject variability and confounding issues.

The collective evidence from these studies suggests that LLLT has the potential to enhance orthodontic treatment outcomes by accelerating tooth movement. However, the degree of effectiveness can vary depending on the parameters such as the laser wavelength, power, and the duration of application, the application protocol, and individual patient responses. This variability underscores the importance of further research to optimize laser application protocols for orthodontic treatments, aiming to achieve more consistent and predictable outcomes.

Vibrational therapy

A total of seven reviewed studies from several countries [37,38,39,40,41,42,43] provided a comprehensive overview of the impact of adjunct vibrational therapy on OTM (Table 2). These studies collectively involved 251 patients, spanning a broad age range from 13 to 50 years, with a balanced representation of genders, via a vis the different orthodontic treatment approaches e.g. clear aligners and fixed appliance therapy. The common vibrational device used in these studies was AcceleDent, except for a study conducted in Japan [38], which did not specify the device type used.

These studies reported the application of a consistent vibration intensity of around 30 Hz, with forces ranging from 0.2 N to 0.3 N. The application protocol was relatively consistent, with daily durations of 20 min being the most common, except for a single study by Mayama et al. [38] who used a shorter vibration period of 3 min daily for monthly visits.

These adjunct vibrational interventions were carried out over 6 weeks to 6 months. The workers employed a variety of assessment methods to evaluate the reported outcomes. These included digital scans, clinical and immunological assessments using ELISA kits for RANKL and osteoprotegerin (OPG) levels, and measurements of tooth movement through digital and 3D modeling techniques (Table 2). These methodologies provided an objective measure of the rate of tooth movement and other relevant orthodontic parameters, ensuring the reliability of the findings.

The reported outcomes from these studies were mixed. Most reviewed studies found that vibrational therapy did not significantly affect the rate of tooth movement or pain related to the overall orthodontic treatment process, the canine retraction rate, or the space closure treatment duration. However, Mayama et al. [38] and Pavlin et al. [42] reported that vibrational therapy significantly accelerated tooth movement when used as an adjunct to static orthodontic forces. These cumulative findings suggest that a number of confounding variables, such as the type of orthodontic treatment and the specific protocol parameters, such as vibration intensity and application duration, may influence the impact and effectiveness of vibrational therapy in OTM.

Probiotic therapy

Data from a total of seven randomized clinical trials [44,45,46,47,48,49,50], were reviewed to evaluate the effectiveness of adjunct probiotics in fixed orthodontic treatment and to maintain or improve gingival and periodontal health.

The number of enrolled patients in these studies varied, yielding 334 patients. They were predominantly teenagers, ranging in age from 10 to 30. Most participants were reported as medically fit or healthy, with some studies reporting oral hygiene indices, including the plaque index, active caries, and salivary Streptococcus mutans counts. The gingival condition was generally noted as `healthy` in some studies.

The studies employed various probiotic delivery modes, including lozenges, liquid drops, kefir (a fermented milk product), toothpaste, and yogurt. Lozenges were used in multiple studies with daily administration, while liquid drops were diluted in water and taken once daily. Kefir and toothpaste were administered twice daily, and yogurt was consumed daily during specified periods, Table 3. The duration of probiotic administration ranged from a short period of 3 weeks up to a prolonged administration period of 17 months (Table 3).

The reviewed studies illustrate the mixed effectiveness of probiotics in managing oral health during OTM. Some studies reported no significant changes in plaque indices or microbial counts. In contrast, others noted significant improvements in conditions such as salivary pH, reduction in S. mutans levels, and decreased incidence of halitosis. For instance, Pinto et al. [49] and Cildir and colleagues [50] used Bifidobacterium animalis in yogurt form with contrasting outcomes. While the former [49], reported no significant difference between the control and experimental groups Cildir et al. [50] found a salutary reduction in salivary streptococci. These studies highlight the potential variability in response to the same probiotic strain, possibly influenced by study design or participant characteristics.

In another study, Alforaidi et al. [45] observed a significant increase in plaque pH but no substantial changes in bacterial counts using the strain Lactobacillus reuteri as a probiotic. This indicates that the probiotic may have altered the oral ecosystem or the oralome, but not the total population of the microbiota. Ebrahim and others [44] tested multi-strains of probiotics in patients undergoing OTM and did not observe significant changes either in the plaque index or S. mutans counts, while Alp et al. [47] reported a decreased level of putatively pathogenic oral bacteria using kefir dietary supplements in combination with a bacteriocin-laced toothpaste.

Gizani and team [48] evaluated the effect of Kefir and probiotic toothpaste groups compared to controls during OTM on the incidence of white spot lesions, a surrogate indicator of caries activity in the oral cavity. They did note a reduction in salivary lactobacillus counts, suggesting a limited impact of the probiotic on enamel demineralization. Benic et al. [46] used another probiotic strain, Streptococcus salivarius M18, and reported only a limited reduction in halitosis and minimal impact on other oral health indicators.

Overall, the reviewed studies highlight the variable effectiveness of probiotics in managing oral health during OTM, with some studies showing mildly positive results while others show no significant changes. The variability in outcomes may be influenced by factors such as probiotic strain, delivery mode, study design, and participant characteristics. Clearly, much more research is warranted before any conclusions are made on the beneficial effect of adjunct probiotics daring OTM.

Effect of adjunct therapies on pain during teeth alignment

The most common complaint of patients undergoing orthodontic treatment is the overall pain levels, particularly during chewing and biting food [51]. This is likely to be impacted by the age, gender, pain threshold, and the force applied in each individual case.

Some studies have associated LLLT and vibration therapy with significantly reduced pain levels during tooth movement [52, 53]. The mechanism involved in such analgesic effects is unclear, but LLLT is claimed to have antinociceptive and modulating properties [52]. Furthermore, such vibrations induced by LLLT are thought to alleviate PDL compression during tooth movement, thus improving blood supply and preventing the local accumulation of inflammatory mediators. Another potential explanation lies in the ‘gate control’ theory, which proposes that pain perception may be alleviated through the concurrent stimulation of nerve fibers transmitting non-noxious stimuli.

However, the RCTs included in the current review did not find significant differences in pain levels between patients in the test and control groups for either LLLT [32] or vibrational therapy. Differences in methods used by multiple investigators and the lack of standardized protocols might explain the mixed results in the literature.