Impacted Palatal Canines and Diode Laser Surgery: A Case Report

Introduction Maxillary canine is the most frequent dental element that could likely remain impacted in the bone structure, with a percentage between 1 and 5%. This study presents a case report using a diode laser for surgical-orthodontics disinclusion of a palatal mucosal impacted permanent left upper canine (2.3) and the simultaneous application of an orthodontic bracket. Methods After cementation of the trans-palatal bar to the upper first molars with a hook for orthodontic traction, local anaesthesia with articaine was performed, followed by surgical operculectomy using a diode laser (810 nm wavelength, continuous wave mode with a power output of 3 W, and a 0.4 mm diameter optical fiber), and the orthodontic bracket with a passive metal looped ligature was applied. Subsequently, active elastic traction was applied on 2.3 and the upper arch was bonded for the application of a series of orthodontic wires, lace-back, and metal ligatures. A progressive reactivation of the elastic traction and extraction of 6.3 was necessary to translate the canine into the correct arch position. Results Diode laser surgical-orthodontic disinclusion of impacted upper canine was performed successively, resulting in a dry surgical field ideal for orthodontic bracket adhesion. No pain and no swelling have been reported from the patient. The orthodontic treatment allowed the canine to be moved to the correct position in the arch. Conclusions This case showed that the diode laser is a valid alternative for the surgical-orthodontic disinclusion of an included tooth element.


Introduction
After the third molar, maxillary canine is the most frequent dental element that could likely remain impacted in the bone structure, with a percentage between 1 and 5%, depending on the patient. It is more common in females than in males, with a ratio of 2 : 1, and only 8% of patients are bilateral [1]. Impaction of the maxillary canine has a ratio of 10 : 1 to mandibular canine and 85% of the upper impaction are palatal [2].
It is essential to make an early diagnosis of the impacted canine to plan the treatment of this dental anomaly in advance and to properly replace this tooth in the arch as soon as possible, considering the importance of canine guidance role in the occlusion and consequently in the correct body posture. [10]. Early diagnosis of canine displacement in relation to the surrounding structures is mainly based on radiographic examination: in Panoramic X-ray more mesial is located in the canine crown, further likelihood of canine eruption is reduced [11].
The choice of treatment in the patient with an impacted canine changes with the age, oral health, and etiologic factors [3,12]: monitoring of the impacted element, in the absence of clinical problems [13], extraction of the deciduous element, if the impacted permanent canine is close to eruption [3], extraction of the deciduous tooth and simultaneous uncovering of the permanent tooth with the application of an orthodontic appliance to increase the space in the arch, and allowing the physiological eruption of the canine [13]. In some cases, it is possible to perform dental reimplantation, when the orthodontic treatment turns out to be too complex, unsuccessful, or not accepted by the patient [13].
At the end of growth, surgical-orthodontic treatment is the only choice to align teeth in the dental arch; alternatively, it is possible to extract the impacted element with subsequent prosthetic or implant-prosthetic treatment [3].
Laser is the acronym of light amplification by stimulated emission of radiation, and it represents a new technology introduced in Dentistry by Theodore Harold Maiman in 1960, but only in 1989, Nd:YAG laser and CO 2 laser were commercially available in the dental market [14]. The light emitted is monochromatic, collimated, and coherent [15]. The essential elements of a laser device are a sounding box in which an active medium is stimulated by a pumping process in a population inversion and in a suitable geometry of the optical feedback elements. Depending on the active medium (gas, liquid, or solid), laser radiation could be in the ultraviolet, visible, or in infrared section of the electrophotometer spectrum [16].
Different authors described laser efficacy in the treatment of oral pathologies, carrying out studies on photodynamic therapy [17,18] and surgical procedures [19,20]. Laser provides an excellent alternative to conventional surgical techniques for soft tissue [21]. Many authors described the use of laser in surgical treatments, such as gingivectomy, labial, lingual frenectomies, and fiberotomy [22]. Furthermore, laser can prevent aphthae and cold sores, ablate benign and irritant tissue excess, correct lip, and tongue bands [23]. Laser can also be used in endodontics to remove bacteria from infected teeth [24]. Laser plays an important role in the treatment of periodontal disease: it can modulate many inflammatory pathways, improves wound healing by stimulating fibroblast proliferation, it has a positive biomodulatory effect on bone healing, it performs an antimicrobial activity, and could be a reliable adjunctive agent to mechanical debridement in the non-surgical treatment of periodontal disease [25]. Additionally, it is also used to treat dentin hypersensitivity [26]. Laser can also be useful in dental bleaching: studies have shown how it can accelerate the release of free radicals within the bleaching gel to decrease the duration of the treatment [27]. Some authors described how low-level laser therapy and photodynamic therapy after scaling and root planning can improve the therapeutic outcomes in patients affected by chronic periodontitis [28]. In the literature the role of laser in cavity preparation, carious removal, and pulp therapy is also discussed [29]. Meanwhile, laser, safe and effective technology, has become widely used in dentistry. The potential advantages include less or no bleeding during the surgical procedure, reduction, or elimination of the need for local anaesthesia, reduced postoperative pain, and less patient anxiety [30].
Finally, laser can be applied in orthodontics to etch enamel prior to adhesive application and orthodontic brackets [31] and can reduce pain following band application on maxillary first molars for orthodontic treatment [32]. Photobiomodulation (or low-level laser therapy) with laser or LED can also be used to reduce pain intensity during and following lower third molar extraction and to improve symptoms related to Burning Mouth Syndrome through a reduction of the capillary diameter [33,34].
Since there are few studies assessing laser application's advantages in surgical-orthodontics disinclusion of an impacted canine, the aim of the present study is to present a case report using a diode laser for the disinclusion of an impacted permanent left upper canine (2.3) and the simultaneous application of an orthodontic bracket.  The facial profile was normal, the facial angle was slightly increased (171.3°), while the nasolabial angle was slightly decreased (93.3°). Upper incisors were correctly inclined, in fact, the angle formed by the upper incisor's longitudinal axis and bispinal plane (Sna-Snp) measured 107.9°, whereas lower incisors were retroclined, considering that the angle formed by the lower incisor's longitudinal axis and mandibular plane (Go-Gn) measured 87.8°. Intraoral pictures (Figures 1(a)-1(c); taken with Nikon Digital Camera D3500, Nikon Corporation, Tokyo, Japan) showed coincident dental midlines, deep bite, conservative treatments on upper central incisors, and upper lateral incisors' malposition. Overjet measured 0 mm, while overbite measured 4 mm. The patient presented class I molar and class I canine on the right with upper central incisors discolouration. On the left, the patient showed class I molar, while canine clas-sification was not possible. Lower deciduous canines were still present, left maxillary lateral incisors were rotated and many diastemas could be found. The morphology of the upper arch was correct, the retroincisive papilla was hypertrophic, and the first upper maxillary molars were rotated. The lower arch showed a correct morphology as well, lower left canine was lingually inclined. There was no dentoalveolar discrepancy. Bolton's analysis was appropriate, considering that the impacted canine was the same size as the contralateral teeth and excluding the lower left canine. Furthermore, clinical recordings highlighted normal Periodontal Screening and Recording and slight mobility on upper central incisors, multiple gingival recessions in the upper and lower posterior jaws and good oral hygiene.

Case Report
Clinical and radiological recordings led to the diagnosis of the upper left canine's palatal impaction and surgical exposure of the impacted tooth was planned for subsequent orthodontic traction. The impacted canine provided a "sector 2" position with an α angle, formed by the tooth's midline and long axis, of approximately 80°and a short distance from the alveolar ridge [35].

Treatment
Objectives. The aim of the treatment is surgical operculectomy of the mucosal tissue overlying the left upper permanent canine (2.3) in palatal mucosal impaction, with good surgical haemostasis, allowing intra-operative adhesion of the orthodontic bracket, thus exerting a more rapid onset of orthodontic traction. The extraction of the deciduous canine (6.3) is necessary to allow the permanent canine to be moved into the dental arch after the disinclusion has been completed. Another possible alternative is the use of the electric scalpel, which presents different risks associated with its use, including burns due to the use of high-frequency current, fire risks due to the presence of combustible liquids or gases in the room where it is used, and electrical risks due to the radiated power, which may disturb any equipment applied to the patient [36].
The last alternative is a conventional surgical approach using a cold-blade scalpel, with the consequent risks of intraand post-operative bleeding and the impossibility of maintaining a dry surgical field, essential to ensure proper adhesion of the orthodontic bracket, the need to apply sutures, potential difficulties in wound healing, and increased postoperative pain [37].  Figure 2). The patient and all staff wore protective glasses to prevent eye damage [38]. After local anaesthesia (Septanest, articaine hydrochloride 4% with adrenaline 1/100,000), a diode laser (Fotona XD-2, Fotona d.o.o., Ljubljana, Slovenia) was used to perform surgical operculectomy, being an element in superficial palatal impaction, with the following parameters [39]: 810 nm wavelength, continuous wave mode with a power output of 3 W and a 0.4 mm diameter optical fiber (Figures 3(a) and 3(b)). Figure 4 shows how the surgical incision did not cause intra-operative bleeding, thus creating an ideal condition for the adhesion of the orthodontic bracket. No pain and no swelling have been reported from the patient.
The bonding protocol used is as follows [40]: etching of the enamel with 35% phosphoric acid applied for 20-30 seconds and rinsing for an equivalent time. Drying using aspiration to obtain the chalky white appearance of the enamel. Application of light cure adhesive (3M™ Trans-bond™ PLUS Color Change Adhesive, 3M Company, St. Paul, MN, USA) on the enamel and on the intrados of the orthodontic bracket using a Microbrush® (Microbrush International, Algonquin, IL, USA). Positioning of the orthodontic bracket (3M Unitek APC™ II Victory Series™, 3M Company, St. Paul, MN, USA) and application of continuous pressure for a light curing time of twice 20 seconds under constant suction (Starlight Pro, Power Output 1400 mW/cm 2 , Mectron S.p.A.). Immediate traction with an elastic connection to the wire: if an error has been made in the bonding protocol, the orthodontic bracket is immediately taken off and a new bonding procedure is begun.
The orthodontic bracket was placed with a passive metal looped ligature, secured with composite ( Figure 5). No sutures and no additional analgesic or antibiotic were recommended, thanks to the photo-bio-stimulating effect (LLLT) of laser [41]. The patient was discharged with necessary postoperative instructions for maintenance of good oral hygiene and keeping the area clean.
The patient was visited with a follow-up of 2 weeks, twice, and monthly thereafter. After 2 weeks, active elastic traction on 2.3 has been applied and one month after surgery the upper arch was bonded through Straight-Wire MBT™ technique with a 0.14 ″ NiTi arch-wire (3M™ Uni-tek™ Nitinol Classic Archwire, 3M Company, St. Paul, MN, USA), performing a mesial lace-back 1.2-2.2 and metal ligation on 2.2 with preformed ligature wire 0.10 ″ (K4210-25, Leone S.p.A. Ortodonzia e Implantologia, Sesto Fiorentino, Italy; Figure 6).
Subsequently, the canine was gradually translated into the correct position in the dental arch by progressive reactivations of elastic traction with elastic cotton threads (Leone, Sesto Fiorentino, Italy), lace-back 1.2-2.2, and metal ligatures on 2.2 and 2.4 with preformed ligature wire 0.10 ″ (K4210-25, Leone); in addition, a super elastic NiTi archwire (0.12 ″ ) upper arch has been used (3M™ Unitek™ Nitinol Classic Archwire, 3M Company). Table 2 shows the procedures checklist of surgicalorthodontic disinclusion of the left upper canine (2.3) in palatal mucosal impaction and its orthodontic translation in the upper arch.
The patient is still undergoing orthodontic treatment to finalize therapy for closing diastema between 2.2 and 2.3.

Treatment
Results. After excision, the patient had no signs of respiratory distress, and no feeding difficulty was reported from the parents. After 2 weeks and 1 month  Case Reports in Dentistry follow-up, the intraoral wound healed without complications and no signs of infection ( Figure 6); 3 months after surgery, the position of the upper canine can be appreciated and thanks to the orthodontic traction applied ( Figure 7); 12 months after surgery, the upper canine 2.3, once included, is positioned at the level of the dental arch but a diastema remains between 2.2 and 2.3, for which orthodontic finalization is necessary to close it (Figures 8(a)-8(d)).
2.6. Discussion. This case report described surgical disinclusion of a left upper canine using a diode laser, followed by orthodontic treatment to translate the impacted canine into the dental arch, highlighting some advantages, such as no intra-operative bleeding, thus providing orthodontic bracket adhesion, no sutures, and no post-operative pain or swelling. In the literature, there are several articles in which laser technology has been used in the surgical management of impacted teeth; however, to our knowledge, no case reports have not yet been presented in literature where an 810 nm wavelength diode laser has been used to perform surgical operculectomy of the palatal impacted canines with a subsequent intra-operative application of the orthodontic bracket. A previous clinical study showed the application of a 980 nm wavelength diode laser for surgical operculectomy of a palatal included left upper canine, preventing bleeding and need for sutures, reducing pain, and allowing placement of orthodontic brackets [42]. A recent case report showed a surgical operculectomy of both impacted upper permanent canines through a CO 2 laser, postponing orthodontic bracket placement to a later date and highlighting many advantages, such as no bleeding, no need for sutures, relative ease, and speed of the procedure, reduced or no postoperative symptoms, antimicrobial activity, and rapid wound healing [43]. A case series study showed a combination of two laser (Nd:YAG and Er:YAG) for the surgical treatment of a left upper canine in osteo-mucosal impaction. Er:YAG was used for hard    5 Case Reports in Dentistry tissue while Nd:YAG for soft tissue. Er:YAG does not show a haemostatic effect, therefore the surgical field was coagulated with Nd:YAG, ensuring bracket adhesion to enamel, and also reducing or avoiding the need for anaesthesia and reducing post-operative pain [44].
In addition, numerous studies in the literature showed the positive effect of the laser on soft tissue, leading to no post-operative pain, no discomfort, no post-operative bleed-ing, and optimal healing by second intention through the formation of a thin, aesthetically excellent scar. In fact, patients rate the procedure as well tolerable and acceptable [45][46][47].
A brief review of the dosimetry and techniques used in previous clinical studies is reported in Table 3.
Studies in the literature point to some important disadvantages in the use of the other surgical alternatives, which contributed to the choice of using the diode laser. Specifically, the use of the CO 2 laser results in thermal damage and a stress effect on soft tissue cells, evident through the presence of elongated cells with fusiform nuclei devoid of nucleoli (therefore inactive), depletion of glycogen, and a reduction in the expression of immunocytochemical markers of intracellular proteins, nuclear cell cycle proliferation, and apoptosis [49]. This cellular damage is also determined following the use of the Er:YAG laser; however, it is significantly reduced, highlighting the possibility of faster healing [49,50]. An important disadvantage of this laser, considering the importance of having a dry operating field to be able to apply the orthodontic bracket, is the absence of a coagulating effect [49,50]. Obviously, the same disadvantage is represented using a cold-blade scalpel [37]. The Nd:YAG laser has an unsatisfactory analgesic effect and, consequently, local anaesthesia is required and the fibrous tissue is not easily removed [51]. Finally, the electrosurgical scalpel presents numerous disadvantages and risks associated with its use, from risk of burns, due to the use of  Case Reports in Dentistry high-frequency current, to a fire risk, due to the presence of combustible liquids or gases in the room where it is used, in an electrical risk, due to the radiated power that can disturb various medical devices applied to the patient. Furthermore, it has been shown, from a histological, histochemical, and immunocytochemical point of view, that the epithelial damage due to the use of electrocautery is higher than the epithelial damage induced using the CO 2 laser, delaying the healing of the surgical wound more [36,52]. This study has some limitations. First, this is a case report with a short-term follow-up. More cases with longterm follow-up are needed to prove the success of this technique. Finally, we can also consider a limitation: laser equipment can involve a high investment and require a learning curve to achieve an optimal result. Based on these observations, several clinical trials are needed to evaluate the advantages and disadvantages of different laser and electrosurgery in surgical disinclusion of impacted teeth.

Conclusion
This case report shows how an 810 nm diode laser can be used during orthodontic treatment for dental exposure without causing post-operative pain and swelling and how it allows maintaining a dry field in order to apply an orthodontic bracket during the operation.

Data Availability
The authors confirm that the data supporting the findings of this study are available within the article.

Consent
A written informed consent was obtained from all patients before the commencement of the study.