Management of Dental Malocclusions Compounded by a Missing Anterior Tooth
Sachin S. Kakodkar
Pradnya S. Kakodkar
A missing tooth co-existing with dental malocclusion is a trite scenario. Whether this space is to be closed by orthodontic tooth movement or occupied with a prosthetic replacement is the ‘bone of contention’ in this matter. This article describes two such cases with minor Class I malocclusion lacking an incisor tooth that underwent orthodontic correction of malocclusion with fixed appliances followed by prosthodontic intervention to regain arch integrity. The merits and shortcomings of available treatment options are also explored.
The dental clinician frequently encounters patients presenting not only with malocclusion of varying degree but also edentulous intra-arch spacing attributable to missing teeth. Congenital absence of certain teeth is well documented. Teeth most frequently missing congenitally (unilateral or bilateral) are the maxillary lateral incisors followed by the maxillary second premolars and mandibular central incisors. Teeth may also be extracted when they are hopeless and beyond salvation (due to massive destruction of tooth structure from carious lesions, teeth debilitated by severe periodontal breakdown, teeth with root fractures, etc.).
Malocclusion being an issue, the orthodontist must deliberate how to deal with the dental arch ‘vacancies.’ Condensing large toothless spans of long standing in adults where the cortical plates have collapsed and shrunken alveolar ridge forms a barrier, especially in the mandibular posterior region is a formidable challenge, assertively vetoed by some investigators. When such a daunting task is embarked upon, one must be wary of the perils of root resorption, gingival dehiscence, periodontal defects and improper root parallelism owing to heavy force exertion.[2-4] Corticotomy, alveolar ridge expansion and the ‘regional acceleratory phenomenon’ (rapid localized bone turn overand swift orthodontically-induced tooth movement) engendered by bone damage are facilitative protocols indicated in such a circumstance. Even when space closure is technically feasible and there are no obvious impediments, executing this plan is tantamount to modifying the patient’s existing occlusal scheme with fixed orthodontic hardware and prolonged care. Without the ‘crutch’ of a permanent retainer, the durability of an end result effected in this manner is suspect. After weighing the pros and cons of the sundry available therapeutic options, if the practitioner zeroes in on prosthetic rehabilitation, orthodontics is an invaluable adjunctive resource – it not only redresses the miscellaneous facets of dental malocclusion (alignment, levelling, decrowding, interdental space closure and redistribution, etc.) but also ideally positions the abutment teeth and reclaims arch length lost by the spontaneous gravitation of teeth toward empty gaps. Correcting axial inclinations of teeth upgrades periodontal status and circumvents pulp exposure during tooth preparation for prosthetic work. A good rapport and coordination between specialists of these two dental disciplines is vital for a successful outcome.
Case Reports :
A 38-year-old lady was tormented by the window-like opening between the front teeth and a left-sided tooth poised awkwardly in the gum. A history of childhood trauma and early extrication of the left central incisor was adduced. The face was proportionately well-balanced, straight in profile with a low mandibular plane angle. Smile aesthetics were compromised by the extant dental malocclusion. Intra-oral examination revealed an Angle’s Class I malocclusion. The upper left lateral incisor was found occupying the place of the lost central incisor and the canine beyond it was overlapping, ectopically erupted, higher-up in the vestibule and in labioversion (facial crown tipping). A big void was discerned on the same side between the maxillary lateral incisor with the canine overriding it and the first bicuspid. On the right side, the maxillary canine was in palatal crossbite. The lower dentition exhibited mild imbrication in the anterior sector and a ‘no tooth’ zone amid the left first and third molar where the second molar was removed because of gross caries and periapical involvement (Figure 1).
In the upper jaw, the two objectives of orthodontic treatment were to first descend and later drive back (i.e. distalize) the upper left canine thereby attaining a Class I canine relation, and to enable the upper right canine to jump out of the underbite. In the lower jaw, orthodontics sought to align the lower anterior dentition and drag the left wisdom tooth mesially to lock the arch.
An 0.022” Roth prescription preadjusted edgewise appliance was the remedial instrument for dental malocclusion. Fixed treatment was initiated with the drop and levelling of the maxillary left canine by nickel-titanium wires utilized in tandem with rigid stainless steel base wires for anchorage. Canine distalization was executed next by sliding the canine posteriorly along a 0.017” x 0.025” stainless steel arch wire with a compressed and active open coil spring.
The crossbite involving the upper right canine resolved without any special effort during the alignment phase. In the lower anterior segment, some interproximal enamel reduction was carried out and the teeth were then aligned with soft nickel-titanium followed by stiffer stainless steel round and rectangular arch wires. The lower left third molar was protracted forward on a 0.019” x 0.025” stainless steel rectangular wire with the succor of active tie-backs (traction of stretched elastomeric rings). The final 0.019” x 0.025” stainless steel wires ligated to all bracketed teeth in both arches continued for four additional months so that the features built into the appliance system (torque, tip, in-out) may express consummately. Part-time wear of an upper removable plate with circumferential bow was advised. A flexible lingual wire retainer was bonded to the lower anterior teeth to perpetuate their correction. A tooth-supported metal-free three-unit ceramic bridge was installed to reinstate upper arch continuity. Post-treatment, the smile esthetics scaled up several notches gratifying for the patient (Figures 2).
A 22-year-old female patient was disquieted by the show of her upper front teeth. The upper left lateral incisor had been extracted during childhood after a traumatic fracture. Teeth in the anterior sector of the upper jaw were slowly but surely drifting toward the left side enlarging the interdental spaces. The maxillary dental midline had deviated away from the mandibular dental and facial counterparts. The upper left central incisor was endodontically treated and capped with an all-ceramic jacket crown. A rufescent, puffy band of gingival tissue bunched around the margin of this restoration, hinted at possible biologic width violation. The mandibular dental arcade exhibited splendid alignment except for the left canine which was tenuously displaced toward the lingual. The case was diagnosed as a Class I malocclusion with bidental protrusion and spacing (Dewey’s subtype 2). Facial proportions were relatively well-balanced and no lip procumbency or perioral muscle strain was spotted (Figure 3).
TREATMENT PLAN AND ALTERNATIVES
After much deliberation, a plan involving space redistribution and artificially replacing the missing upper left lateral incisor was adopted. The age-old formula of four bicuspid extraction and anterior tooth retraction with an active fixed appurtenance was rebuffed in view of the patient’s age, the straight facial profile and nice lip configuration. The alternative option of orthodontic space shrinkage by mesializing all the maxillary teeth in the left quadrant was not implemented since the posterior occlusion would be disrupted and relapse was feared.
An 0.022” MBT prescription preadjusted edgewise appliance was employed for the fulfilment of treatment goals. An activated open coil on an upper 0.018” round Wilcock stainless steel wire created adequate space at the missing left lateral incisor site while concomitantly closing space around other teeth, paralleling the prospective abutments and converging the upper dental midline with the facial center line. In the mandibular arch, the lingually malposed left canine sorted out during the levelling and alignment phase by the usual progression from soft nickel-titanium to stiffer steel wires. The last pair of coordinated arch wires (0.019” x 0.025” rectangular stainless steel) were tied in place for four months to unleash the three-dimensional adjustments programmed into the bracket system. A flexible retainer wire was bonded to the lower six anterior teeth. A month before the conclusion of active orthodontics, the jacket crown overlying the left central incisor was cut out, yielding the gingiva an opportunity to heal. Once the inflammation had subsided, and the appliance components were dismantled, the left central incisor and canine were prepared for a tooth-bracing bridge. The finish lines (shoulders) on both were equigingival. After about a week of temporization, a three unit all ceramic bridge was finally luted. The patient judged her smile to be more alluring now than ever before (Figure 4).
When confronted with intra-arch spacing, dentists belabor over the quandary: to close or not to close? …the debate on this topic is still raging. For missing incisor teeth, treatment choices include canine substitution, single tooth implants and tooth-supported restorations. Dental auto transplantation is also possible. Let us succinctly evaluate all these three options:
Orthodontic space closure and canine substitution: One research study demonstrated that orthodontic space closure yields an end result acceptable to patients without impairing temporomandibular joint function and boosts periodontal health when contrasted with cases where prosthetic stand-ins supplanted missing teeth. The highlights of this method are the probability of completing treatment relatively sooner and the feasibility of developing alveolar process by mesial guidance of the canine. However, canine substitution is also tagged with pitfalls like the inordinate crown shaving necessary for reshaping, higher gingival margins and the shade incongruence viz-á-viz the central incisors. Hybrid composite resin restorations, individual tooth bleaching, enamel-bonded ceramic veneers gloss over the arising esthetic compromise, but the ‘conservative’ fabric of management is eroded. Other demurrals to the orthodontic approach are that functional occlusion is conceded and longevity of the product is dubious. In addition, here, the first premolar, substituting for the canine will demand crown lengthening after orthodontic intrusion to elevate their buccal gingival contours and cosmetic makeover. After these embellishments, a modified group function is in offing on the working side. A bonded fixed lingual wire retainer is obligatory and may even be supplemented by a Hawley’s passive plate for night-time wear.
Single tooth implant: The big trump of implants naturally is that the contiguous teeth can be left intact, and this is especially advantageous in young patients. However, implants in the anterior maxilla, besides being prohibitively expensive, are fraught with biologic and technical hazards that can manifest within a few years (This builds a formidable case for opening spaces in the buccal segments, rather than anteriorly, and lodging the implant in the bicuspid terrain). Deeper implant insertion is prudent when the osseous ridge is labiolingually deficient; otherwise the bony dehiscence befalls and resorption of the fragile labial bony layer gradually denudes the implant suffusing the soft tissue with a dark, cyanotic hue and/or leading to gum recession. Due to age changes in tooth level, an osseointegrated implant must be stationed only after facial growth has ceased. In adolescent patients who are through with orthodontics, the long waiting period before implant fixation can prove frustrating and interim arrangements (Maryland bridge, removable partial denture) are seldom appreciated.
- RESIN-BONDED FPD – The resin-bonded fixed partial denture (FPD) is rather conservative because the adjoining teeth remain unscathed, but debonding is frequent in cases with deep overbite and incisor proclination. Abutment tooth mobility, bruxism habit are other contraindications.
- CANTILEVERED FPD – By its root length and crown morphology, it is an ideal base for a cantilevered pontic. The prosthesis must be cleared from all excursive/eccentric contacts to prevent loosening, fracture or migration of the abutment.
- CONVENTIONAL FULL-COVERAGE FPD – Unequivocally, the most invasive of all the three varieties and generally indicated when replacing an existing bridge or if neighboring teeth enfeebled by gross caries, endodontic ministrations, or other structural undermining call for reinforcement with full crowns.
Autotransplantation:[8,9] This particular option is invoked more often when the upper central incisors are traumatically avulsed. Dental autotransplantation is the extraction of a donor tooth from its original (erupted/impacted) site to a prepared one or an extraction socket in the same individual. A successful auto transplantation will induce alveolar bone growth at its new destination in growing patients. The donor tooth must have two thirds of its root formed. The recipient site must be readied with surgical burrs and should be wider than the donor tooth. The donor tooth is harvested with utmost care to ensure that the entire dental follicle is intact and there is no injury to the periodontal ligament. The tooth is placed out of occlusal contact and splinted with light wire to allow physiologic movement. The facial surface of the auto transplanted tooth is also positioned 0.5 mm lingual to those of adjacent teeth for composite restorative work. A healing period of 6 weeks is recommended before application of orthodontic force. Risks involved in this procedure are ankyloses, pulpal necrosis and root resorption. When the surgical operations are precise, survival rates of 98 to 100 % have been reported.
In both the cases narrated above, the curative strategy adhered to was simple, time-saving and most conducive to enduring stability. Every component of malocclusion was rectified, the missing anterior tooth surrogated with a rigid three-unit fixed prosthesis and the dental arches sealed. The posterior dental occlusion was not perturbed as this might incite relapse. Prolonged retention was not crucial. Smile aesthetics and the subjects’ self-esteem were heightened after treatment. The only challenge left for the patients is to maintain the foreign bodies in their mouth by scrupulous oral care, both personal and professional.
Orthodontic and prosthodontic disciplines can converge and collaborate when dealing with dental malocclusions, also characterized by spacing to deliver high-quality outcomes. Whether orthodontic maneuvering alone will suffice or adjunctive orthodontics furthered by prosthodontic intervention is optimal, hinges on a myriad of factors, all of which must be considered merit-wise, staying focused on patient’s interest and keeping ego clashes aside.
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