The primary objective of this study was to compare the aesthetic outcome of palatally impacted canines treated with an open or closed surgical exposure technique using the Maxillary Canine Aesthetic Index (MCAI) at least 1 year after debonding. Secondary objectives were set on the periodontal outcome, tooth color, pulpal status, and self-reported contentment.
The sample of this retrospective study consisted of 53 patients with an average age of 20 years and 7 months at the time of the investigation. A total of 53 canines were investigated. All canines were aesthetically scored with the MCAI. Other outcome variables were investigated, such as gingival inflammation, pocket probing depth, vitality, percussion sensitivity, and tooth color. All patients received a questionnaire to evaluate their appraisal of different parameters.
A statistically significant difference ( P < 0.001) was found between the groups treated with an open and closed technique in terms of the MCAI. The closed technique scored excellent in terms of aesthetics, whereas the open technique scored good. The closed technique had more discoloration ( P < 0.001) and a delayed response to the cold test ( P = 0.021). In general, patients were satisfied with both techniques but considered the treatment time to be very long.
A closed surgical exposure of palatally impacted maxillary canines is preferred in terms of aesthetics when measured with the MCAI. There was no difference between the 2 techniques in terms of periodontal outcome. Canines treated with a closed exposure tended to have a darker color and delayed response to cold testing.
Palatally impacted canines exposed with open or closed surgical techniques were assessed.
The closed technique produced better esthetic outcomes according to the MCAI scoring.
Teeth treated with a closed technique had a delayed reaction to sensitivity testing.
They showed more discoloration, suggesting a higher incidence of pulp canal obliteration.
Maxillary canines are the second most frequently impacted teeth after the third molars. The overall prevalence varies between 0.9% and 2.2%, , with an incidence ratio twice as high in female patients. , Palatal to buccal impaction ratio is 3:1. , Impaction is defined as the failure of tooth eruption at its appropriate site in the dental arch, within its normal period of growth. The maxillary canine has an important role in occlusion, aesthetics, and continuity of the dental arch.
Different etiologic factors of maxillary canine impaction such as dental discrepancy, the ectopic position of the tooth-germ, lack of space, lack of guidance, presence of hard and soft tissue pathologies, or genetic factors are mentioned in the literature. ,
Treatment options for impacted canines are (1) interceptive removal of the deciduous canine, (2) surgical exposure with or without orthodontic traction to align the malpositioned tooth, (3) autotransplantation of the permanent canine, (4) removal of the permanent canine followed by orthodontic alignment to close the remaining space, prosthetic or restorative treatment, or reinforced resin-bonded bridge or implants, and (5) no treatment. ,
Considering surgical exposure of the impacted maxillary canine, several surgical procedures and classifications have been proposed in the literature. It is generally accepted to make a distinction between open and closed surgical techniques. With the open technique, the gingiva above the canine is excised, and the overlying bone layer is removed. The wound is packed with gauze or special wound packing material to prevent the gingiva from closing so that spontaneous eruption of the canine can occur. Sometimes a cleat is bonded once the tooth is exposed in order to assist eruption and alignment further. The main drawback of this technique is a longer postoperative sensitivity and recovery. , The major advantage is reduced surgical time as well as eruption time. However, it should be considered that the shorter eruption time in the open technique could be explained by choosing this technique when only the mucosa is overlaying the impacted canine.
The closed technique consists of a full-thickness flap that is made above the site of impaction. The bone above the canine is removed, and during the procedure, a bracket or cleat is bonded to the tooth surface. Through a gold chain or twined wire, the cleat or bracket is connected to the orthodontic appliance. After the bonding, the mucoperiosteal flap is closed and sutured in place with the gold chain or wire exiting from the surgery site. The main advantages are less postoperative discomfort, faster recovery from pain, and overall lower postoperative complication rates. Drawbacks are an increased surgical time and being a more complex and sensitive technique.
Most of the studies on impacted maxillary canines have their focus on the periodontal outcome with respect to probing depth, bleeding on probing, the sulcus bleeding index, width of the keratinized gingiva, and attachment loss. According to the Cochrane Database of Systematic Reviews, 3 articles with low risk of bias have their focus on the aesthetic outcome after surgical exposure and alignment of the canine. The Cochrane review about this subject (Cochrane database of systematic reviews 2017 CD006966) considers Parkin et al and Smailienė et al as qualitative research papers. Parkin et al evaluated the aesthetics of posttreatment canines through a panel of orthodontists and laypeople. No difference was found between the open and closed methods. Smailienė et al investigated tooth color, position in the dental arch, inclination, and shape as aesthetic criteria. They did not include gingival parameters in their aesthetic appraisal. Furthermore, they did not report whether their reporters were blinded.
One of the most important shortcomings in previously conducted research is that it is difficult to pool the data and compare the outcome of the studies because of a lack in the standardization of the parameters used to evaluate the aesthetic outcome. Most parameters used by different authors focus on tooth characteristics while ignoring gingival characteristics. The lack of a generally accepted ranking or classification system is mentioned in the Cochrane review by Parkin et al. Outcome heterogeneity is one of the major problems in health care research. This problem can be addressed by determining a Core Outcome Set, such as an index for the aesthetic evaluation of impacted maxillary canines.
The Maxillary Canine Aesthetic Index (MCAI) was developed in response to the lack of a standardized method of evaluating and measuring maxillary canine aesthetics. This index can be used in both research and clinical settings. It takes 12 different soft tissue and tooth characteristics into account. Characteristics of the gingiva are included in the overall aesthetic evaluation of the canine. The main advantages of the MCAI are that future results can be compared and the system combines visible soft tissue (gingival) and hard tissue (tooth) parameters into 1 comprehensive scoring system. Additional information is provided in Table I .
|Parameters investigating PIC||Scoring|
|Marginal gingiva||5||1 (<3 mm)||0 (>3 mm)|
|Recession||(apical to MGJ)||(coronal to MGJ)||(no recession)|
|Marginal gingival thickness||Thin||–||Thick|
|Mesiodistal crown angulation||Distal||Straight||Mesial|
|Parameters comparing both canines||Major discrepancy||Minor discrepancy||No discrepancy|
|Curvature of marginal gingiva||2||1||0|
|Soft tissue color and texture||2||1||0|
|Root convexity and/or bulging of the root||2||1||0|
|Vertical tooth position||2||1||0|
|Parameters investigating the relationship between the PIC and neighboring teeth|
|Buccolingual angulation crown according to the neighboring teeth||2||1||0|
Besides the aesthetic outcome as expressed by the MCAI, we also evaluated parameters related to pulpal characteristics such as tooth color, percussion sensitivity, and pulpal sensitivity. The fact that in our study, the time between the end of treatment (removal of brackets) and the start of the investigation was almost 5 years, allowed us to evaluate the slowly evolving pulpal changes. This long observation time is in contrast with the relatively short times found in the literature, where pulpal characteristics after surgical orthodontic extrusion of impacted canines are not often considered.
Subjective appraisal was included in our study because of the increasing importance of Oral Health-related Quality of Life and the ability to compare this data with other current research projects.
Given the lack of standardized reporting of aesthetic outcome (lack of Core Outcome Set) in the literature and the short follow-up time of the pulpal status, the primary aim of the present study was to conduct a retrospective study to compare MCAI between 2 patient groups, one treated with an open and the other with closed exposure technique. Secondly, the pulpal and periodontal status of impacted canines were investigated between those 2 groups. Thirdly, we investigated the color of the canines treated with either an open or closed exposure technique.
Material and methods
A convenience sample of 53 patients who met the requirements was invited to participate in the study. Forty-five of the 53 patients were recruited from a private office circuit with access to orthodontic and periodontal specialties. The remaining patients were treated by the same orthodontic and maxillofacial surgery team at the University Hospitals Leuven. The mean age of the 53 patients at the time of investigation was 20 years and 7 months (standard deviation [SD], 7.58 years). Twenty-eight patients were treated with a closed technique and 25 with the open technique (see Table II ). In our sample, 13 patients were male. The average time between the time of investigation and the removal of the brackets was 4 years and 11 months after orthodontic treatment (SD, 3.67 years).
Exclusion criteria included systemic disorders and congenital craniofacial deformities. Cleft lip and palate patients were also excluded. Inclusion criteria were set on at least 1 year after debonding of the orthodontic appliance.
The closed treatment group consisted of 28 patients who underwent a closed surgical exposure technique, whereas 25 patients were treated with an open technique. The surgical procedure used in the open technique group is slightly different from the general information presented in the introduction. The procedure was performed as follows: a mucoperiosteal flap was made, the overlaying bone layer was removed, and afterward, the flap was repositioned apically toward the cementoenamel junction and sutured in place. An eyelet or bracket was bonded to the tooth surface, and the crown was covered with a wound packing material (COE-Pak, GC, Leuven, Belgium). All canines underwent traction after the procedure with an extrusion plate or with a gold chain connected to a fixed appliance.
The diagnosis of impaction was made on a clinical basis combined with a radiologic diagnosis on panoramic radiography to ensure that both groups had the same degree of severity impaction. All panoramic radiographs were investigated. The analysis was performed using Impax software (version 126.96.36.1998; Agfa HealthCare, Mortsel, Belgium). Angulation was determined by measuring the angle between the canine and the vertical line parallel to the mesial surface of the central incisor. The occlusal plane was determined by drawing a line through the incisal edge of the central incisor and the mesiobuccal cusp of the first molar. The distance to the canine cusp tip was measured perpendicular to the occlusal plane. The sector was determined using the Ericson and Kurol classification. If only the analog panoramic radiograph was available, a manual measurement on tracing foil was performed. The duration of traction was also taken into account. Time was measured from the date of surgery until the bracket on the canine could be connected with an archwire.
No statistical difference was found between the 2 study groups for the baseline parameters (see Table III ). The angulation of the included canines and distance from the canine tip to the occlusal plane did not differ significantly between the 2 groups before treatment. The chi-square test did not show a difference between the sector of the impacted canines ( P = 0.19). Therefore, the severity of impaction in both groups is considered the same. The duration of active traction on the canine was not significantly different between the 2 groups ( P = 0.12). Furthermore, the duration of the overall orthodontic treatment did not differ significantly between the 2 study groups ( P = 0.08). The choice of a closed vs open approach was based on the preference of the orthodontist and not on criteria such as the initial position of the canine.