Indian board of Orthodontics Case Report: Orthodontic Management of a Palatally Impacted Maxillary Canine

Abstract

Abstract

A 19-year-old dental student reported with a chief complaint of malaligned teeth and an impacted upper right canine (13). On clinical and radiographic examination, he had a slightly depressed maxilla in the upper right region, right deviation of nasal bridge, acceptable facial profile, horizontal, palatally impacted canine whose crown was almost reaching the midline, spaced upper anteriors, excessive gingival display on smile, deep bite, and 34 in crossbite. Comprehensive orthodontic therapy along with surgical exposure of 13 helped in achieving all the treatment objectives to great satisfaction without any adverse effects on the periodontium or the dentition. This case report details the diagnosis and clinical management.

Introduction

The permanent maxillary canines are only second to the third molars in order of dental impactions. Becker and Chaushu ¹ stated that while genetics could be attributed as a cause of impacted canines, the path of eruption of the canine is strongly influenced by environmental factors. He classified these factors as local hard tissue obstruction, local pathology, departure from or disturbance of normal development of the incisors, genetic or hereditary factors.

Maxillary canines are important esthetically and functionally, but patients with impacted maxillary canines are perceived to be more difficult and time-consuming to treat than the average orthodontic patient. Should you try to bring the impacted tooth into the arch, expecting that this procedure will add extra time and expense to an average treatment, or should you extract the offending tooth, saving time and money for the patient but perhaps at the expense of esthetics and long-term function?

Stewart et al ² investigated answers to these questions and concluded that patients with unilateral impaction required, on average, just over 3 months more to treat than control patients with no impaction. The greater the distance the impacted canine was from the occlusal plane, the greater the angulation and more medially displaced it was. The younger the patient at the start of treatment, the longer the duration of orthodontic treatment. When the impacted canine crown was at a distance from the occlusal plane of less than 14 mm, treatment time averaged 23.8 months; a distance of more than 14 mm required an average treatment time of 31.1 months.

Palatally impacted canines can cause, due to their absence in the line of occlusion, a lack of alveolar bone development in the place where it would ideally have been, especially if the deciduous canine has exfoliated early. It then becomes imperative for the orthodontist to factor any gingival concerns, functional and esthetic, in treatment.

This case report details the various aspects of diagnosis and management of a palatally impacted maxillary canine.

Pretreatment Assessment

AD, a 19-year-old male, was a dental student and reported with a chief complaint of malaligned teeth and an impacted canine. There was no other relevant medical history related to the canine impaction.

Extraoral examination revealed mild asymmetry due to a depressed canine eminence in upper right maxilla, deviated nasal bridge, slight canting of the interpupillary (3 degree) and the intercommissural (1 deg) lines, normal vertical facial proportions, convex facial profile, competent, nonprotrusive lips. There was an excessive show of upper incisors along with a gummy smile (Figures 1-3).

Figure 1.

Extraoral Pretreatment Frontal

Figure 2.

Extraoral Pretreatment Profile

Figure 3.

Extraoral Pretreatment Smiling

Intraoral examination revealed exaggerated canine fossa due to absence of root prominence of 13, exaggerated root prominence of 12, 14, and all upper anterior teeth, irregular gingival contours of 11, 12, 21, 22, 23 with increased thickness of attached gingiva and presence of pseudopockets. The oral hygiene was fair. All teeth except 13 were present. The third molars were partly erupted (Figures 4-8).

Figure 4.

Intraoral Pretreatment Left Lateral

Figure 5.

Intraoral Pretreatment Frontal

Figure 6.

Intraoral Pretreatment Right Lateral

Figure 7.

Intraoral Pretreatment Upper Occlusal

Orthodontic evaluation revealed 8 mm spacing in upper arch and 3 mm crowding in lower arch.

Occlusal evaluation revealed an overjet of 1.5 mm and an overbite of 4.5 mm. The upper midline was shifted to the right and lower shifted to the left. Angle’s Class I molar and Class II canine were present in left buccal occlusion and Angle’s Class I relationship in right buccal occlusion. The tooth #34 was in lingual crossbite. There were asymmetric upper and lower arch forms. There was a reverse curve of Spee in upper arch causing a pseudo-deep bite. There were wear facets on palatal cusp of 24, and 24 showed slight rotation.

Figure 8.

Intraoral Pretreatment Lower Occlusal

Figure 9.

Pretreatment Lateral Cephalogram Tracing

Figure 10.

Pretreatment OPG Snapshot

Figure 11.

Difficulty of Treatment Analysis of OPG

Model analysis indicated an Ashley Howe’s index of 37% suggesting that the case was borderline extraction. Tooth-size analysis indicated average sized upper and lower total tooth material. Nance Carey’s index suggested extraction of lower second premolars. Bolton’s analysis suggested normal proportions (while calculating we assumed an equal width of 13, 23).

General Radiographic Examination

Pretreatment lateral cephalogram tracing in Figure 9, orthopantomogram (OPG) and spiral CT scan were evaluated.

The OPG snapshot (Figure 10) showed a horizontally impacted no. 13 almost touching the midline. It was analyzed for difficulty of treatment of canine impaction and prognosis assessment as per Ericson and Kurol. ³ The horizontally impacted and palatally placed canine was in zone 5 (crown in the region of upper incisors), with crown at an average vertical height, poorly angulated (>30 deg to the midline), and the root tip positioned above the first premolar (Figure 11).

Figure 12.

Slice Numbers of the Spiral CT Scan

The upper midline was shifted to the left with respect to the anterior nasal spine (ANS).

Spiral CT analysis (Figures 12-16) revealed crown of #13 approximately 6-7 mm palatal to the root of #11 with lingual surface towards palatal soft tissue; the root tips were above and palatal to the root tip of 14. The crown was almost touching the midline. Alveolar bone in the region of 13 was thinned out due to early exfoliation of #53. Slices 53 and 54 (Figure 16) show the alveolar bone thinning in the 13 region and the bony concavity in the alveolar ridge. Occlusal radiograph (Figure 17) showed the proximity of the root of the impacted canine with respect to the apices of the premolars.

Figure 13.

Slice Numbers 73-78, Crown Tip to Mid-Crown

Figure 14.

Slice Numbers 65-72, Crown Position

Table 1.

Pretreatment and Posttreatment Cephalometric Findings as per Indian Board of Orthodontics Requirements

Indian Board of Orthodontics Cephalometric Analysis (Adjusted for Magnification)
Variable	Normal	Pretreatment (A)	Posttreatment (B)
Sagittal Skeletal Relationship:
SNA	82	84.5	81
SNB	80	78	77
ANB	2	6	4
Wits appraisal	0-1 mm	6 mm	5 mm
Dental Base Relationship:
Upper incisor to NA (mm/deg)	4,22	−1,7	5,31
Lower incisor to NB (mm/deg)	4,25	7,27	10,31
Upper incisor to SN plane	103	91.5	112
Lower incisor to MP angle (IMPA)	90-100	91	95
Dental Relationship:
Interincisal angle	131	139	113
Lower incisor to APo line	2 mm	1 mm	6.5 mm
Overbite	2 mm	4.5 mm	1.5 mm
Overjet	2 mm	1.5 mm	1.5 mm
Vertical Skeletal Relationships:
Maxillary–mandibular planes angle	25	29	31
SN plane–mand plane	32	33	35
Upper anterior face height	0.45	57 mm	58.5 mm
Lower anterior face height	0.55	75 mm	77 mm
Face height ratio	82%	76%	76.5%
Jarabak ratio	62-64%	63.5%	62%
Maxillary length (McNamara)		112	110.5
Mandibular length–effective		135	136.5
Soft Tissues:
Lower lip to Ricketts E plane	−2 mm	1 mm	1.5 mm
Nasolabial Angle	90-110	120	114

Figure 15.

Slice Numbers 57-64, Cemento Enamel Junction to Mid-Root

Figure 16.

Slice Numbers 49-56, Root Tip Views

Figure 17.

Occlusal Radiograph of Upper Arch Taken Prior to Surgical Exposure

Table 2.

Holdaway’s Soft Tissue Analysis ⁵

Parameter	Pre	Post	Inference
Basic U/lip thickness	20 mm	19 mm
U/lip thickness	19 mm	18 mm
Lip strain	−1 mm	2 mm	Lip strain within normal range
Incisor exposure at rest	6 mm	0 mm	Incisor exposure reduced
H angle	26	24	Lip protrusion has not worsened with incisor protrusion

Pretreatment cephalogram was traced and the findings have been tabulated in Tables 1 and 2. They revealed a skeletal Class II base with slightly retrognathic mandible and tendency towards a vertical growth pattern. The upper incisors were retroclined and lower incisors displayed compensatory proclination with an acceptable soft tissue profile and an increased nasolabial angle. There was negative lip strain and increased incisor exposure at rest. Facial proportions indicated an increased lower facial height. Increased basal plane angle indicated an increased mandibular anterior dental height.

Based on the above evaluations, the following diagnosis was arrived at along with a problem list and treatment objectives

Diagnostic Summary

The 19-year-old patient presented with a dental Class I on a skeletal Class II base with a vertical growth pattern. The upper and lower anteriors were retroclined. There was a palatally positioned horizontally impacted 13. There was mild maxillary asymmetry due to a depressed upper right canine region with asymmetric upper and lower arch forms and deviated midlines. There was canting of the interpupillary plane and a minor cant of the intercommissural line. There was upper dental spacing and lower dental crowding with a pseudo-deep bite. The upper anterior gingival contours were irregular with pseudopockets and increased attached gingival heights. There was mild rotation of 14, 24 and a lingual crossbite of 34. The oral hygiene was fair. The soft tissue profile was acceptable.

Problem List

1. Palatally impacted 13

2. Upper arch spacing

3. Lower arch crowding

4. Asymmetric arch forms, dental rotations

5. Deep bite

6. Retroclined upper and lower incisors

7. Irregular gingival contours, increased gingival exposure on smile, and pseudopockets in upper anterior teeth

Aims and Objectives of Treatment

1. Alignment of impacted 13 and upper and lower anterior and posterior teeth

2. Correct upper and lower anterior inclination

3. Correct deep bite

4. Close upper arch spaces

5. Decrowd lower arch

6. Correct asymmetric arch forms and midline shift

7. Correct irregular gingival contours

8. Reduce incisor exposure

9. Achieve Class I molar and canine relationship

10. Establish and maintain harmonious soft tissue balance

Treatment Plan

Despite the difficulty involved in treating, in time and effort, the unfavorably positioned 13, the treatment of choice was to attempt to save it for the following reasons.

Absence of canine eminence resulted in a depressed facial appearance of the upper right canine region. It was assumed that by sufficient labial torque application to the canine root after alignment, at least some alveolar support could be regained.

A shorter treatment plan against the selected plan would have been to extract the impacted canine and restore the missing canine with a prosthodontic implant. The oral surgeon opined that bone graft would be additionally required to place the implant with an optimum inclination. However, the patient refused the same.

The patient was well aware of the difficulty and time involved in correcting the canine impaction and assured his cooperation towards his preferred mode of treatment.

Space required for decrowding the lower anteriors would be gained by slight proclination of the lower anteriors.

Deep bite would be corrected by intrusion of the upper anterior and by correcting the inclinations of the upper and lower anteriors. This was favored by the increased nasolabial angle and the negative lip strain at pretreatment.

No extractions were required. A 018 (McLaughlin Bennett Trevisi) MBT prescription metal preadjusted appliance was chosen.

Special Anchorage Requirements

We planned to use a piggyback light wire spring to upright the root and torque it later in treatment. Second molar bonding would assist in maintaining arch form.

Minor Adjunctive Surgery

1. Surgical exposure of impacted 13 using the palatal flap technique

2. Gingivectomy at the end of treatment to idealize gingival contours and improve smile esthetics

Additional Dental Treatment

1. Recontouring of the incisal edges of the anterior teeth if need be

2. Restorative fillings as and if needed

3. Oral prophylaxis as and when required

Proposed Retention Strategy

Upper Hawley’s retainer plate with a 4-4 labial bow and with a moderate anterior bite plane. Lower lingual bonded retainer with a dead-soft, flat cross-section, sandblasted Stainless steel (SS) wire.

Additional Notes on Treatment Plan

Care was to be taken to ensure that there were no adverse effects on the roots of the teeth or on the periodontium in course of the prolonged treatment duration.

Prognosis for Stability

Once the canine would be in alignment, the lack of spaces in upper arch, proper interincisal relations, idealized arch forms, good cusp-fossa interrelationship, and harmonious soft tissue balance would help in leading to a good prognosis for stability.

Treatment Progress

The treatment had an active treatment time of 43 months and the retention is still in place (Table 3).

Table 3.

Key Stages in Orthodontic Treatment Progress

Sr. No.	Date	Stage
1	March 10, 2012	Upper arch full bond and 016 round Nickel-Titanium (NiTi) placed
2	July 21, 2012	Upper arch consolidated into anterior segment and posterior segments with 16 × 22 SS wire
3	October 5, 2012	13 exposed using the palatal flap technique. Indirect traction was provided in a distal and buccal direction using a light coil spring on a base rigid SS 16 × 22 wire (Figure 18)
4	December 22, 2012	Lower arch fully bonded with 014 NiTi wire
5.	March 11, 2014	Modified Begg uprighting spring placed on a direct bonded lower incisor bracket on 13 to achieve root long axis parallelism with 12, 14 (Figure 18)
6	August 19, 2014	014 SS labial root torquing auxiliary on a rigid 16 × 22 SS archwire (Figure 19)
7	July 14, 2015	Lower 17 × 25 SS finishing wire placed with steps to adjust vertical heights
8	September 15, 2015	Upper arch 17 × 25 SS finishing wire with a mild curve of Spee
9	October 30, 2015	Upper and lower arch fixed appliances removed

Figure 18.

Series of IOPAs to Show the Progress of the Movement of Canine Crown Initially With a Tipping Force from Coil Spring and Later Using Begg Root Uprighting Springs

Figure 19.

Light Wire Root Torquing Auxiliary to Torque the Canine Root Labially

Subsequently minor enamel recontouring was done for the upper incisors and canines along with a laser gingivectomy to idealize the gingival contours.

Posttreatment Assessment

Photographs, OPG, lateral cephalogram and IOPA upper anteriors were taken at the end of treatment.

Root parallelism was achieved in all teeth with slight deviation in 32, 34. Alveolar bone heights were normal. Mildly reduced bone level was seen in the mesial of 13. The third molars were partially erupted even at the end of treatment (Figures 20 and 21).

Figure 20.

Posttreatment Lateral Cephalogram

Figure 21.

Posttreatment OPG

Posttreatment cephalometric findings (Tables 1 and 2) were interpreted as follows.

There was an improvement in the ANB angle along with the correction of the retroclination of the upper anteriors and some minor late mandibular growth. There was a marginal opening of the mandibular plane angle favoring the correction of the dental deep bite. The retroclined lower anteriors were also proclined slightly to achieve a favorable interincisal relation. The lip strain consequent to treatment was well within Holdaway’s acceptable limits. The upper incisor was intruded to reduce incisal exposure at rest. The superimpositions are shown in Figure 22.

The patient and his parent were extremely satisfied with the results of the orthodontic treatment. All the stated objectives were achieved to satisfaction. The treatment not only vastly improved the facial and smile esthetics (Figures 23-25) but also did not cause any adverse effects on either the roots or the periodontium despite the long duration of treatment.

Figure 22.

Cephalometric superimposition

Figure 23.

Extraoral Posttreatment Frontal

Figure 24.

Extraoral Posttreatment Profile

Figure 25.

Extraoral Posttreatment Smiling

Figure 26.

Intraoral Posttreatment Left Lateral

An overjet of 1.5 mm and an overbite of 2 mm were achieved. There was a slight shift of lower midline to the right by less than 0.25 mm. Class I canine and molar relations were achieved on both sides with excellent improvements in the Occlusal Indices. (Table 4). Crossbite of 34 was corrected (Figures 26-30).

There were no mandibular deviations during closure. A mutually protected occlusion with canine guidance during excursive movements was achieved. Excellent interdigitation of the upper functional lingual cusps into the fossae of the lower teeth was achieved. Enameloplasty was done on 13, 21, and 22 for microesthetics.

Figure 27.

Intraoral Posttreatment Frontal

Figure 28.

Intraoral Posttreatment Right Lateral

Figure 29.

Intraoral Posttreatment Upper Occlusal

Figure 30.

Intraoral Posttreatment Lower Occlusal

Figure 31.

Intraoral Posttreatment Frontal After Laser Gingivectomy

Figure 32.

Extraoral Posttreatment Smiling After Laser Gingivectomy

Complications Encountered During Treatment

1. The impacted 13 had pointed incisal edges with sloping marginal ridges. They were very prominent compared to the blunt edge of the erupted and functional 23. Esthetic recontouring of the incisal edge of 13 was therefore necessitated. The gingival margin of 13 was also way higher than 23. Therefore the 13 was extruded and 23 slightly intruded by bracket positioning. The extrusion of 13 complemented the recontouring of the edge. There was no resultant sensitivity in 13. Fluoride application was done consequently.

2. The impacted canine 13 was discovered to have a morphologically flat buccal contour and different hue. Therefore, an attempt was made to place it as buccal as possible within the constraints of the alveolar bone. Though from an orthodontic perspective it did not feel enough, the patient was more than satisfied with the final 13 position. A laminate mock-up that significantly improved smile esthetics was also shown to the patient but the patient chose to decide on it later.

3. At the time of debonding, poor gingival contour gave an appearance of canting of smile line, but this changed significantly with idealizing the gingival contours with a laser gingivectomy and minor incisal edge recontouring (Figures 31 and 32).

4. There was a loss of approximately 14 months of treatment time due to missed appointments in the course of treatment.

Critical Appraisal

1. Due to the original maxillary asymmetry, a slight cant of 1 deg of occlusal plane to interpupillary line existed at the end of treatment. However, it was not clinically significant to either the patient or his parents or his dental peers. This is supported by literature search which shows that a cant of up to 2 deg was esthetically accepted by orthodontists, general dentists, and laypersons. ⁴

2. There was a slight deviation of less than 3 mm of upper midline to upper face. In addition to the existing maxillary asymmetry, this was also caused due to the deviation of the nasal bridge and ANS to the patient’s right.

3. The 35 had a slight buccal contact with the first molar. However, it offered an excellent cusp-fossa relation with the antagonists.

Table 4.

Occlusal Indices

INDEX	PARAMETER	VALUE
Index of Treatment Need
Dental Health Component	Start	5i
	Finish	1
Aesthetic Component	Start	5
	Finish	1
Peer Assessment Rating (PAR)	Start	UnWt 20 Wt 13
	Finish	UnWt 1 Wt 0
	Change	19 13
	%Change	95 100

Conclusion

As envisaged at the start of the treatment, the duration of treatment was long. However, care was taken to ensure that the forces were light throughout the treatment. Therefore, despite the complexity of tooth movements involved in correcting the canine impaction, all treatment objectives were achieved with a conservative approach and without any significant adverse effect on the teeth or the periodontium.