|Year : 2015 | Volume
| Issue : 1 | Page : 50-55
Salvaging the lost smile in amelogenesis imperfecta
Smriti Kapur Dewan, Aman Arora, Viram Upadhyaya, Manish Vishen
Department of Prosthodontics, Sh. J. N. Kapoor D. A. V. Dental College, Yamuna Nagar, Haryana, India
|Date of Web Publication||30-Jul-2015|
Dr. Smriti Kapur Dewan
Room No. 5, Department of Prosthodontics, Sh. J. N. Kapoor D. A. V. Dental College, Yamuna Nagar - 135 001, Haryana
Source of Support: None, Conflict of Interest: None
Amelogenesis imperfecta has been described as a group of hereditary enamel defects not associated with systemic diseases. Restoration of these defects is important not only because of esthetic and functional concern, but also because there may be a positive psychological impact on the patient. Among various treatments described for rehabilitation of amelogenesis imperfecta, this case report described the rehabilitation of patient utilizing twin stage procedure with aim of improving patient's function, appearance, restoring the proper contacts, and simplifying the prosthetic clinical and lab work procedures. Twin stage procedure is based on the fact that prevents horizontal forces acting during various mandibular excursion in full mouth rehabilitation case, to control horizontal forces which in turn depends upon the condylar path, incisal path, and cusp angle. Among them, role of cusp angle is more supported whereas condylar path and incisal path role is considered unreliable.
Keywords: Amelogenesis imperfecta, full mouth rehabilitation, Hobo twin-stage technique, template
|How to cite this article:|
Dewan SK, Arora A, Upadhyaya V, Vishen M. Salvaging the lost smile in amelogenesis imperfecta. Saint Int Dent J 2015;1:50-5
|How to cite this URL:|
Dewan SK, Arora A, Upadhyaya V, Vishen M. Salvaging the lost smile in amelogenesis imperfecta. Saint Int Dent J [serial online] 2015 [cited 2019 May 23];1:50-5. Available from: http://www.sidj.org/text.asp?2015/1/1/50/161807
Amelogenesis imperfecta, also known as hereditary opalescent teeth, represents a group of hereditary defects of enamel unassociated with any other generalized defects. It is entirely ectodermal in origin and mutations in AMLEX (amelogenin), ENAM (enamelin), Kallikrein 4 (KLK4), MMP-20 (enamelysin) are thought to be responsible for this defect. , Amelogenesis imperfecta can be classified into four types, but it was later revised by Witkop and given various subclasses.  The clinical features may range from poor esthetics, brown pigmentation, decreased vertical dimension to even painful sensitivity of teeth. The teeth are vulnerable to pulpal inflammation. Enamel maybe entirely absent in radiograph and if present it will be very thin layer usually on the cusp tips and interproximal surfaces. Sometimes, radiograph shows indistinct enamel with equal radiolucency to dentin. 
The prevalence of AI is 1 in 14 people to 1.14/1000 depending on type,  1:718-1:14,000 in western countries  and in our part of the world very rare; 0.27% in Indian population. 
The restoration of AI involves meticulous treatment planning and execution of high-standard of treatment protocol. The aim is to provide an ordered pattern of occlusal contact and articulation to optimize oral function, health, occlusal stability, esthetics, and comfort. The indications for occlusal rehabilitation include the following conditions - restoration of multiple teeth which are broken, worn, missing or decayed, faulty FPD work, discolored dentition, developmental defects, and worn out dentition. 
The following goals should be achieved when planning for an occlusal rehabilitation:
- Static co-ordinated occlusal contact of the maximum number of teeth when the condyle is in comfortable, reproducible position
- An anterior guidance that is in harmony with function in lateral eccentric position on the working side
- Disocclusion by the anterior guidance of all posterior teeth in eccentric movements
- Axial loading of teeth in centric relation, interproximation, and function. 
In cases of developmental anomalies such as amelogenesis imperfecta, as was diagnosed for the patient in this case report, loss of vertical dimension of occlusion is also a concern. In treatment of such cases, it is necessary to increase vertical dimension to provide sufficient space for reconstruction, but this increase should be within extent of lost vertical dimension and should not exceed the accommodating limit of musculature.
Many different occlusal schemes have been suggested by various authors for full mouth rehabilitation patients which includes Pankey-Mann Schuyler concept, Hobo's Twin tables concept, Youdelis concept, Nyman and Lindhe concept, etc.Anterior guidance is crucial in human occlusion because it influences molar disclusion that controls horizontal forces. Molar disclusion is determined by a cusp-shape factor and an angle of hinge rotation. The Hobo-Takayama method for creating molar disclusion by using a twin stage technique is described in the present case. This technique develops anterior guidance to create a predetermined, harmonious disclusion with the condylar path. Condition 1 is used to incorporate a cusp-shape factor and Condition 2 is used for the angle of hinge rotation. This method does not require special equipment and is an uncomplicated procedure suitable for daily practice. The mystery of establishing the optimal anterior guidance is also clarified, including accurate development of a specific degree of disclusion desired by the dentist.
| Case Report|| |
A healthy 23-year-old female patient reported to the Department of Prosthodontics, with a chief complaint of generalized small-sized teeth with excessive wearing, causing difficulty in chewing. She was extremely dissatisfied with her appearance.
Initial evaluation of patient encompasses a detailed social, dental and medical history. The patient had a noncontributory medical and dental history. Clinical examination of the patient revealed yellow teeth with absence of enamel, attrition of the posterior teeth especially on the left side being more pronounced in the mandibular teeth, reduced clinical height of the teeth, marginal gingivitis, and melanin pigmentation of the gingiva [Figure 1]. The history further revealed use of a hard brush and a vigorous brushing habit. The bristle marks on the posterior teeth confirmed that the loss of tooth structure was due to the wrong brushing habit, more pronounced on the left side of mandibular teeth [Figure 2].
|Figure 2: Attrition of teeth and bristle marks on the mandibular posterior teeth|
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The absence of enamel suggested of amelogenesis imperfecta which was also confirmed from the patient's orthopantomogram.
To determine the plane of occlusion for which a lateral cephalogram [Figure 3] of the patient was taken. A transparent film containing concentric circles is overlaid on the radiograph. The concentric circles are drawn with a radius varying from 30 mm to 180 mm, at 1 cm intervals [Figure 3]. Manipulating the transparent film on the radiograph, the best circle that crosses the posterior and anterior definition points of the curve of Spee and allows the adequate distribution of the posterior prosthetic space is chosen [Figure 3]. By this, the optimum radius of the curve of Spee is established in relation to the dento-skeletal structures specific to the patient.
To reproduce this curve of spee in the patient's dentition a template with the appropriate radius, is selected from a collection of clear plastic disks [Figure 4] which had radii of curvature corresponding to the circles on the transparent film overlay. This template was later used during the wax up to reproduce the curve of spee in the patient's prosthesis.
Following this the treatment was divided into:
- Periodontal phase
- Endodontic phase
- Prosthodontic phase.
- 2 mm Crown lengthening was done in relation with all maxillary and mandibular teeth [Figure 5]
- Depigmentation of complete maxillary and mandibular, anterior and posterior gingiva was done [Figure 5]
- Patient was advised to use 2% chlorhexidine mouthwash and taught proper oral cleansing habits
- The patient was kept on 1-month healing period before starting the endodontic phase.
Intentional root canal treatment of all the maxillary and mandibular teeth was done prior to the prosthodontic rehabilitation.
After all the above treatment procedures were completed:
- Maxillary and mandibular impressions were made with irreversible hydrocolloid (Plastalgin Septodont, France) and diagnostic casts were obtained. Based on the patient's moderate loss on vertical dimension, a hypothetical increase of 3 mm in vertical dimension of occlusion was carried out using centric record
- Then the maxillary cast was mounted on a semi adjustable articulator (whip mix) using face bow transfer and the mandibular cast was mounted using the centric record
- A 3 mm occlusal splint [Figure 6] for the maxillary arch was fabricated using a Bioplast Sheet and was provided to the patient as a part of reversible interventional modality to evaluate adaptation of the patient to altered VDO. The patient was kept in a diagnostic and observational period for 6 weeks
- The diagnostic wax-up was done over the mandibular teeth using the template selected previously with the maxillary cast removed from the articulator [Figure 7]. The template was placed between the hinge axis and the mandibular canine. It was stabilized over the teeth using a custom made auto polymerizing acrylic resin stent. Following this the maxillary cast was fixed back to the articulator and the wax-up was completed in accordance with Condition 1 and Condition 2
- The tooth preparations were done [Figure 8] and impressions of maxillary and mandibular teeth were made in irreversible hydrocolloid (Plastalgin Septodont, France), poured in type III dental stone and casts were obtained for fabrication of provisional restorations. For this, first quadrant wise putty indexes of the diagnostic wax-up were made, then the indexes were loaded with tooth colored auto polymerizing resin (SC-10 Jagdish Lal Sethi and sons, New Delhi) and were adapted over the casts obtained after preparations. Thus, the indirect method of making provisionals minimizes patient discomfort and chairside time. The provisionals were given at an increased VDO [Figure 9]
- Once the patient was adapted to this position, a final full-arch impression for maxillary and mandibular teeth were made using polyvinyl siloxane impression material (3M ESPE soft Putty, Korea) with the temporaries removed and casts were poured in (Type IV) die stone. The maxillary cast was mounted on a whip-mix articulator using facebow transfer [Figure 10]
- Now to transfer the vertical dimension and centric relation the patient was made to bite on aluwax till the desired VDO using a digital Vernier Calliper [Figure 11]. This interocclusal record was used to mount the mandibular cast
- The wax pattern was fabricated with the help of the template as explained for the diagnostic wax-up and was completed in accordance with Condition 1 and Condition 2 [Figure 12] and [Table 1]. All the wax patterns were cast and metal copings were tried in the patient's mouth. Definite restorations with PFM crowns exhibiting a vital and natural appearance with proper contour and shade were fabricated
|Table 1: Articulator adjustment values for Hobo twin-stage procedure (degree) |
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- Permanent cementation was done with GIC type 1 luting cement [Figure 13]. Oral hygiene instructions were given and follow-up was carried out at regular intervals [Figure 14].
| Discussion|| |
There are alternative restorative procedures for amelogenesis imperfecta. ,, Each method has limitation and they should be critically reviewed prior to deciding a treatment plan. The treatment for patients with amelogenesis imperfecta is related to many factors including the age of patients, the socioeconomic status, the type and severity of the disorder, its intraoral manifestation and esthetic and functional demands. Treatment plan should have common goal-functional, esthetic and longevity of restoration, yet the approaches being slightly different.
Full-mouth reconstructions involving full arch preparations, impressions, provisional restorations, and master casts are regarded as simultaneous reconstructions. A variety of techniques may be used in simultaneous constructions to obtain complete arch dies and mounted casts. These techniques assist in concomitant laboratory construction of the units. When all of the prepared teeth are on a single articulator, there is flexibility in developing the occlusal plane, occlusal theme, embrasures, crown contour, and working casts. , The establishment of occlusal plane according to Orthlieb  template technique has the canine teeth, posterior teeth and hinge axis are all in the same vertical plane, and the thickness of the template guides the technician, so that it is easy to work with wax. An alternative approach to the full-mouth simultaneous reconstruction is to complete one quadrant before beginning another. The advantages of this approach are that it is primarily chairside and includes preparation and final impressions of select teeth, maintenance of vertical dimension, quadrant anesthesia, and shorter, predictable appointments. The disadvantages of the quadrant reconstruction include restrictions for achieving ideal occlusion when altering the vertical dimension, occlusal plane, and embrasure development. The existing opposing dentition limits the reconstruction of an isolated quadrant. Esthetic consistency can be compromised because the porcelain restorations are made in stages. 
There has been a conflicting opinion whether to work simultaneously or to work on different segments of the arch individually. The proponents of the later theory states that work can be completed more quickly and easily and with much more comfort for the patient. The total chairside and laboratory time for rehabilitation is significantly reduced.  The disadvantages include unpredictable patient visits, full arch anesthesia, full arch chairside treatment restorations, multiple occlusal records, and difficulty in recording vertical dimension.
Previously, the condylar path was the principle focus of attention for gnathologists as it did not change during adulthood and the determination of anterior guidance remained the sole discretion of the dentist. Thus, anterior guidance and condylar path were considered independent factors.
Restoring full mouth with twin stage procedure has its own advantage as the basic concept involved in the new procedure reproduce the occlusal morphology of the posterior teeth without the anterior segment and produce the cusp angle coincidence with standard values of effective cusp angle. Second, reproduce anterior morphology with the anterior segment and provide anterior guidance which produces a standard amount of disocclusion. The anterior guidance and the patient's condylar inclination might or might not be in harmony. The amount of disocclusion changes (increase or decreases) in patient's mouth, as this technique followed a fixed value of 40° of condylar inclination. Hence, the amount of disocclusion varies from the predetermined value.
| Conclusions|| |
The restoration of esthetics and functions for these kinds of patients with meticulously done metal-ceramic crown results in better oral health impact profile. A detailed diagnosis and treatment planning is necessary to achieve predictable success in such cases. Full mouth rehabilitation using Hobo's twin stage technique is an easy, less time consuming, and accurate method of rehabilitation which can be conveniently adopted to provide predictable results.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14]