The Impact of Surgical Technique on PDC
Condition: Tooth, Impacted
MeSH terms: Tooth, Impacted
Study type: Interventional

Summary: 
      Permanent canines in the maxilla usually erupt into the mouth at 11-12 years of age. In
      approximately 2% of the Swedish population they fail to erupt, and are then referred to as
      impacted. One severe complication of impacted maxillary canines is damage (root resorption)
      to the roots of adjacent teeth. The root resorption may be so severe that neighboring teeth
      are lost. If the impaction is detected early (at 9-10 years of age), the recommended
      treatment is to extract the deciduous canine, to help the permanent canine to resolve its
      unfavorable position. If there is no improvement of the position of the canine 1 year after
      the extraction, surgical and orthodontic treatment is indicated. Surgical exposure is
      followed by orthodontic treatment with fixed appliance for 2 to 3 years to bring the canine
      into correct position.

      Two different main principles of surgical exposure in palatally impacted maxillary permanent
      canines are the so called closed versus open surgical techniques.

      Closed technique involves surgically uncovering of the canine with a mucoperiosteal flap
      dissected off the bone. The bone covering the canine is being removed and an attachment with
      a chain is bonded to the tooth. The flap is repositioned and sutured back with the chain
      above the mucosa. Shortly after the surgery, orthodontic force is applied via the chain. The
      canine is orthodontically moved beneath the palatal mucosa by forced eruption.

      Open technique involves surgically uncovering of the canine, removing a window of tissue
      around it and placing pack to cover the exposed area. Then the treatment approaches vary
      depending on whether the attachment with a chain is bonded to the exposed tooth at surgery or
      if spontaneous eruption of the palatally impacted canine is expected postsurgically. In both
      alternatives orthodontic force is applied via the chain and the canine is orthodontically
      moved above the mucosa. These two techniques of surgical exposure of palatally impacted
      canines seem to be the two routinely used in Sweden.

      The purposes of this study are to examine, describe and compare the treatment outcomes in
      regard to success and duration of treatment, complications, side effects, cost-benefit
      aspects and patients´ perceptions in closed versus open surgical exposure techniques, in
      cases with palatally impacted canines.

      The objective is to test the null hypothesis that there are no differences in the above
      outcomes between open or closed surgical exposure of palatally impacted canines.
    

Detailed description: 
      Methods of exposing canines are today left to the personal choice of the surgeon and
      orthodontist. According to an unpublished survey among orthodontists in Sweden 2012, 80% of
      them use the closed technique only, 9% use the open technique only and 11% use both
      techniques. This result may be compared to a similar survey performed in the UK, where 29%
      selected a closed surgical technique only, 40% selected an open surgical technique only and
      the remainder chose combinations of techniques.

      Mentioned reasons for preference of the closed technique are less pain and need for
      analgesics and faster recovery of pain, postsurgically. Some orthodontists that prefer the
      open exposure technique have experienced more patient related pain or discomfort in the
      closed exposure technique, in association with activation in orthodontically forced eruption,
      because the palatally impacted canine is moved beyond the mucoperiosteal flap. There are no
      previous studies in this aspect, though.

      Factors as operation time, total treatment time and periodontal health measurements after
      surgical exposure and orthodontic forced eruption of impacted canines, have shown
      heterogeneity in different retrospective studies.

      The management of the palatally impacted canines is a multidisciplinary, time consuming
      treatment, contributing to relatively high society costs, why this study is taking place,
      trying to clarify some issues in the choice of method and treatment.

      Subjects Patients with diagnosis of uni- or bilateral palatally impacted canine/-s planned
      for surgical exposure are included consecutively at three orthodontic centers of the Public
      Dental Health Service in the towns of Orebro, Eskilstuna and Jönköping, Sweden.

      Procedure At the appointment for treatment information, the orthodontist gives potential
      study participants and their parents verbal and written information about the trial. The
      potential study participants and their parents will be allowed at least one week to decide
      whether to participate in the trial and if they agree to participate, the written consent
      will be submitted to the orthodontic centre.

      After informed consent is obtained, the participants are randomly allocated to 1 of 2
      interventions.

      A computer generated randomization is undertaken to ensure that there are equal numbers
      allocated to each intervention. Allocation concealment is held by one individual per centre,
      not involved with the trial, who will be contacted by the consenting clinician when the
      patient is going to be referred for surgical exposure. There will be no stratification for
      age or gender into the two different groups.

      If maxillary deciduous canine are present; they are removed at the time of surgical exposure.
      The two different surgical exposure techniques are described under "Intervention arms".

      The patients are given verbal and written postsurgical information.

      Verbal pre-/postsurgical information consists of the recommendation of:

        -  Analgetic (paracetamol first choice) 1 hour before surgery and there after every 6 to
           8th hour 2 days post surgically, according to the dosage recommended

        -  Tooth paste without sodium is recommended when used directly in association with
           chlorhexidine rinse

      Together with the written postsurgical information, a questionnaire is handed out at the
      surgical clinic to the patients, for assessment of their experience of pain and discomfort in
      the evening of the day of surgical exposure and one week there after. The postsurgical
      questionnaire contains questions that are validated. This questionnaire is submitted to the
      orthodontic centre at the first postsurgical control.

      After surgical exposure orthodontic force is applied; in the closed technique group no later
      than 2 weeks post surgically and in the open technique group when bonding attachment is
      possible. In both surgical exposure groups orthodontic force is applied to the palatally
      impacted canine via the chain attached to the bonded attachment on the canine, to a fixed
      orthodontic appliance.

      Questionnaires are handed out to the patients every 3rd month at the orthodontic clinic, to
      evaluate the patients´ perceptions of pain and discomfort, until the impacted canine is
      orthodontically positioned in the dental arch. These questionnaires are submitted at the
      orthodontic clinic the same day, in association with orthodontic appointment. Questionnaire
      to assess patients´ perceptions of dental anxiety is handed out to the patient before
      treatment, when the impacted canine has erupted and when active treatment is finished in each
      surgical exposure group, at the orthodontic centre. Dental anxiety will be evaluated and
      described according to Cuthbert MI and Melamed BG. The patients are followed until the active
      orthodontic treatment is finished and an orthodontic retainer is fitted.

      Observation schedule and material/registrations:

      Before surgical treatment (T0):

        -  Impression for study cast/ Registrations: sagittal, transversal and vertical relation,
           crowding and spacing of teeth (measured according to the current clinical routine),
           maxillary dental development stage according to Björk

        -  Panoramic radiograph/ Registrations: mesial position of the impacted canine crown,
           mesial inclination of the canine to the midline, distance to the occlusal line according
           to Ericson and Kurol

        -  CBCT (cone beam computed tomography) examination/ Registrations: exact position and
           follicle size of the impacted canine; crestal bone height in the lateral incisor in the
           impacted and nonimpacted contra lateral side in the same patient; root resorption in the
           impacted canine, the incisors and the eventual first premolar in the impacted and
           nonimpacted contra lateral side in the same patient

        -  Clinical examination (according to clinical routine)/ Registrations: periodontal pocket
           depth, gingival bleeding on probing, gingival recession; in the lateral incisor in the
           impacted and nonimpacted contra lateral side in the same patient

        -  CFSS-DS (dental anxiety) questionnaire/ Assessment of dental anxiety

        -  Registration of age, gender, presence of deciduous canine and date of eventual
           extraction of deciduous canine

      The day of surgical exposure (T1):

        -  A questionnaire (for the first evening and one week after surgical exposure)/ Assessment
           of experience of pain, discomfort (measured in VAS-scales) and consumption of analgesics
           one week after surgical exposure

        -  Measurement and registration of operation duration

      Palatally impacted canine erupted; here: when bonding attachment is possible/ approximately
      ⅓-½ of the clinical crown of the impacted canine is exposed intraorally (T2):

        -  Measurement and registration of the duration for the canine to erupt into the oral
           cavity; time between T1 and T2

        -  Registration of presence, type and number of complications/failures associated with
           surgical technique

        -  CFSS-DS questionnaire/ Assessment of dental anxiety

      Previously impacted canine positioned in the dental arch; here: canine ligated to .016x.022
      nickel titanium/standard steel arch-wire in the .018-appliance system and .019x.025
      nickel-titanium/ standard steel arch-wire in the .022-appliance system (T3):

        -  Registration of presence, type and number of complications/failures associated with
           orthodontic treatment

        -  Measurement and registration of duration between T2 and T3

      Orthodontic retainer is fitted/ Active treatment finished (T4):

        -  Impression for study cast/ Registration of sagittal, transversal/ vertical relation,
           crowding/spacing of teeth (measured according to the current clinical routine)

        -  Clinical examination(according to clinical routine/ Registration of pocket depth,
           gingival bleeding on probing, gingival recession in the canine, the lateral incisor and
           the first premolar in the impacted and nonimpacted contra lateral side in the same
           patient

        -  CFSS-DS questionnaire/ Assessment of dental anxiety

        -  Measurement and registration of duration between T3 and T4

      Within 2 months after active treatment is finished (retainer fitted):

      • CBCT examination/ Registration of crestal bone height in the canine, the lateral incisor
      and the first premolar in the impacted and nonimpacted contra lateral side in the same
      patient; root resorption in the canine, the incisors and the first premolar in the impacted
      and nonimpacted contra lateral side in the same patient

      Between the day of surgical exposure (T1) and the day when the previously impacted canine is
      positioned in the dental arch; here: canine inligated to .016x.022 nickel titanium/ standard
      steel arch-wire in the .018-appliance system and .019x.025 nickel-titanium/ standard steel
      arch-wire in the .022-appliance system (T3):

      • A questionnaire is handed out to the patient every 3rd month at orthodontic appointments
      between T1 and T3/ Assessment of patients´ perceptions of pain and discomfort (measured in
      VAS-scales) and consumption of analgesics

      Ethical aspects The Regional Ethic Board of Uppsala University, Uppsala, Sweden, which
      follows the guidelines of the Declaration of Helsinki has approved the study. The Radiation
      Protection Boards of the County Councils of Örebro, Eskilstuna and Jönköping have approved
      the planned radiographic examinations in the study. Patientdata are processed according to
      the laws Personuppgiftslagen, PUL, (1998:204) and Patientdatalagen (2008:355). The
      examinations and treatments used in this trial are the current examinations and treatments of
      palatally impacted canines in Sweden, which have been practiced during several years. All
      surgical exposures and orthodontic treatments are performed by specialists in dental
      pediatrics/ clinicians and specialists in orthodontics, respectively, with many years of
      surgical experience.
    

Intervention name(s): Closed surgical technique; Open surgical technique
Intervention type(s): Procedure; Procedure
Intervention description(s): Surgically uncovering of the impacted canine with a mucoperiosteal flap dissected off the bone
The bone covering the canine is being removed
Attachment with a chain is bonded to the exposed tooth
The palatal flap is repositioned and sutured back with the chain above the mucosa. Shortly after the surgery
The canine is orthodontically moved beneath the palatal mucosa; Surgically uncovering of the impacted canine, removing a window of tissue from around the tooth
Pack/filling material is applied on the tooth
Spontaneous eruption of the palatally impacted canine is allowed expected
The canine is orthodontically moved above the mucosa
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment