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| CASE REPORT |
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| Year : 2017 | Volume
: 3
| Issue : 1 | Page : 21-23 |
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Simplifying complexities of nonparallel abutments
Sheen J Arora, Aman Arora, Divya Malik
Department of Prosthodontics, D.A.V Centenary Dental College, Yamuna Nagar, Haryana, India
| Date of Web Publication | 16-Apr-2018 |
Correspondence Address:
Divya Malik
Department of Prosthodontics, D.A.V Centenary Dental College, Model Town, Yamuna Nagar - 135 001, Haryana
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/sidj.sidj_3_17
The success of the prosthetic rehabilitation in a long-span fixed partial denture (FPD) requires adequate restoration of its function, periodontal health, and esthetics. This case report describes various treatment options to overcome stresses produced in a long-span FPD with tilted molar.
Keywords: Long-span fixed partial dentures, nonrigid connectors, telescopic crowns, tilted molar
How to cite this article:
Arora SJ, Arora A, Malik D. Simplifying complexities of nonparallel abutments. Saint Int Dent J 2017;3:21-3 |
The success of fixed partial denture (FPD) prosthesis requires receptive, sensitive, and insightful diagnostic ability. Moreover, a thorough understanding of the favorable indications and reasonable limitations of abutments and connectors is essential.[1],[2] In case of long-span FPD prosthesis, it is important to carefully examine the length of edentulous span, crown-root ratio, abutment mobility, alveolar bone support, root configuration, root angulations, or the presence of any endodontically treated tooth. Moreover, for the longevity and favorable response of FPDs, it is necessary to have proper opposing occlusion, pulpal condition of the remaining teeth, connector shape, size, and position. However, treatment gets complicated for long-span FPDs when the abutments are tilted, and there is a need to provide common path of insertion for the prosthesis.[3],[4]
In such cases, tooth preparation alone cannot solve the problem; suitable alternative treatment is required such as three-quarter crowns, orthodontic uprighting, locked attachment, and use of telescopic retainers.[1],[2] This case report presents a clinical situation where decreased interocclusal space, short clinical crown height, and excessive tilt of the abutment did not permit the use of conventional aforementioned treatment options. Thereby, a long-span five-unit FPD was used to restore 2nd premolar and 1st molar of the third quadrant with appropriate mechanical solutions so as to break the stress around the abutments and dissipate the forces equally.
| Case Report | |  |
Clinical examination
A 32-year-old female reported to the Department of Prosthodontics in our college with the chief complaint of difficulty in eating. Intraoral examination showed missing 35, 36 and mesially tilted 37. On radiographic examination, all abutments showed good bone support, favorable root morphology. Palpation and percussion of teeth did not reveal any significant pulpal and periapical pathology. Further oral examination revealed mutually protected occlusion. After thorough clinical and radiographical examination, five-unit porcelain fused to metal FPD with a special customized telescopic crown on 37 was planned. In addition, to overcome the undue stresses due to nonparallel abutments in a long-span FPD, it was planned to provide with nonrigid connectors. Metallic primary banding was planned in place of metallic coping on the tilted third molar abutment due to reduced interocclusal space. This was followed by the placement of telescopic superstructure. Telescopic crowns act as a double-crown prosthodontic system which will allow cross-stenting of the dental arch. Moreover, tooth preservation and stabilization can be carried out over a long time.
Procedure
- Preliminary impressions of maxillary and mandibular arches were made with irreversible hydrocolloid and poured in type III dental stone. Endodontic treatment was carried with respect to 37. Prosthetic rehabilitation was carried out in several stages wherein the first-stage tooth preparation of 33, 34, and 37 was completed following the biomechanical principles. The tilted abutment 37 was prepared conventionally with chamfer finish line [Figure 1]. Impression was made with addition silicone putty-wash technique
- It was planned to provide a metal band as a primary coping to receive a superstructure of porcelain fused to metal bridge such that the path of placement is parallel along the long axis of all the abutments [Figure 2]. The primary metal band coping was evaluated for fit and cemented to the prepared tilted abutment using type I glass ionomer cement. This was followed by conventional metal-ceramic crown tooth preparation with a shoulder finish line [Figure 3]
- To reduce stress in this long-span bridge, it was planned to place a nonrigid connector. Final impression was made with addition silicone elastomeric impression material using two-step putty-wash technique. Temporization was done as a five-unit bridge
- Master cast was poured in type IV dental stone, and die pins were attached. This was followed by die cutting and articulation using interocclusal wax-bite record
- Wax patterns were fabricated for teeth 33, 34, 35, 36, and 37. The mortise (female component) of the nonrigid connector was attached to the mesial part of the pontic, and tenon (male component) was attached to the distal part of the retainer. Accurate alignment of the tenon-mortise is very critical as it should be parallel to the placement of distal part of the prosthesis which can be accomplished with a dental surveyor
- Once the casting was done, metal try-in of the individual units was performed to confirm proper seating of the metal framework [Figure 4]. Following this, ceramic layering was done on the metal superstructure [Figure 5]. During luting of the prosthesis, first, the cementation of the mesial segment was done followed by distal segment [Figure 6]
- The patient was given postinsertion oral hygiene maintenance instructions.
 | Figure 2: Metal band given to create parallel path of placement of the superstructure along long axis of the abutments
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 | Figure 3: Shoulder finish line with vertical grooves prepared on the metal band to receive the porcelain fused to metal substructure
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 | Figure 4: Metal try-in done to check the parallel placement of the superstructure along with nonrigid connector
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 | Figure 5: Porcelain fused to metal superstructure with nonrigid connector attachments
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| Discussion | | |
Tilted abutments are angulated teeth in mesial, distal, buccal, or lingual direction depending on the cause and location of the same in the arch. As they are out of ideal centric contact and deviated from normal long axis, such teeth cause food impaction, dental caries, periodontal and occlusal problems creating unstable occlusion, and improper maintenance of oral hygiene. Depending on the severity of the tilt, different treatment modalities such as simple recontouring, three-quarter crowns, orthodontic uprighting, telescopic crowns, and nonrigid connectors can be considered to get the common path of insertion and reduce the amount of stress in tilted abutments.[5],[6],[7],[8] In the present case report, the patient presented with a tilted abutment that was rehabilitated by providing a telescoping crown; moreover, the stress produced in the long-span bridge was reduced using a nonrigid connector.
The telescopic prosthesis is nothing but an artificial superstructure fabricated to fit over metallic primary coping. In this case report, metal band coping was used due to reduced interocclusal space in the posterior region so as to prevent any obstruction during insertion of FPD. The band was fabricated such that it was parallel to the adjacent copings. Such alignment of abutments for fabrication of FPD without over reducing tooth structure resulted in a conservative treatment. In addition, there is reduced amount of stress and possibility of recurrent caries on abutments in long-span FPD. This treatment provides with an easy irretrievability of the superstructure without extraction of the failed abutments and ensures favorable force transmission.[9],[10]
In addition to this, nonrigid connectors provided in the present case long-span FPD, transmitted shear stresses to supporting bone rather than concentrating them in connectors, thereby, minimizing mesiodistal torquing of the abutments and allowing them to move independently.[11],[12],[13] The “double-crown concept” of the telescopic prosthesis and the intrinsic design of nonrigid connector allowed proper dissipation of the masticatory forces. Therefore, accurate planning of the design philosophy is critical in success of the long-span FPDs with tilted abutments.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| References | | |
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| 13. | Pandey P, Mantri SS, Deogade S, Gupta P, Gala A. Two part FPD: Breaking stress around pier abutment. IOSR J Dent Med Sci 2015;14:68-71. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
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