|Year : 2021 | Volume
| Issue : 2 | Page : 132-135
Rehabilitation using semi-precision attachment in fixed partial denture
Ashish Kalra1, S K Roy Chowdhury1, AK Nandi2
1 Department of Prosthodontics, AFDC, New Delhi, India
2 Department of Prosthodontics, CMDC, Chhattisgarh, India
|Date of Submission||10-Sep-2021|
|Date of Acceptance||12-Oct-2021|
|Date of Web Publication||11-Feb-2022|
Dr. Ashish Kalra
AFDC, New Delhi
Source of Support: None, Conflict of Interest: None
The desire to balance between functional stability and cosmetic appeal in partial dentures gave rise to the development of precision attachments, since then, precision attachments have always been surrounded by an aura of mystery. A 35-year-old patient reported a chief complaint of missing upper anterior teeth and wants their replacement. Examination revealed the congenitally missing first and second premolars in the maxillary arch bilaterally, and canines were at first premolar place, which were brought there orthodontically. The patient was planned for 5-unit fixed partial denture from lateral incisor to first molar with semi-precision attachment distal to canine bilaterally, and canines were decided to be converted into the first premolar bilaterally. In this case, it was decided to use the semi-precision attachment and it was procured from Sterngold company, USA. Semi-precision attachments are used to reduce the detrimental stresses and excessive torque on pier abutment, thereby maintaining its health. The decision to use precision attachments in partial denture design should be carefully considered. It is alright to consider such sophistication where the facilities for this precise laboratory work and knowledge of using semi-precision attachment are available.
Keywords: Fixed denture, precision, semi-precision attachment
|How to cite this article:|
Kalra A, Chowdhury S K, Nandi A K. Rehabilitation using semi-precision attachment in fixed partial denture. Int J Oral Health Sci 2021;11:132-5
| Introduction|| |
Esthetically pleasing and comfortable restorations can be given with ever-increasing knowledge of the oral environment, technological improvements, and good armamentarium materials. Today's practitioners are provided with changing techniques and a better understanding of the oral environment. This makes it all the more important to reconcile what is actually feasible with the patient's own expectations.
The desire to balance between functional stability and cosmetic appeal in partial dentures gave rise to the development of precision attachments, since then, precision attachments have always been surrounded by an aura of mystery. The use of precision attachments for partial denture retention is a practice builder for the better class of dentistry and helps to elevate the general standard of partial denture prosthetics. The precision attachment is sometimes said to be a connecting link between the fixed and the removable types of partial denture because it incorporates features common to both types of construction.
| Case Report|| |
A 35-year-old patient reported a chief complaint of missing upper anterior teeth and wants their replacement. History revealed that he had missing teeth since beginning and got the orthodontic treatment done for proclination of upper anterior teeth 5 years back. Examination revealed the congenitally missing first and second premolars in the maxillary arch bilaterally, and canines were at first premolar place, which were brought there orthodontically [Figure 1]. The patient was planned for 5-unit fixed partial denture (FPD) from lateral incisor to first molar with semi-precision attachment distal to canine bilaterally, and canines were decided to be converted into the first premolar bilaterally. Tooth preparation was done and final impression was made using putty and light body using two-stage double-mix putty-wash impression [Figure 2]. Cast was fabricated and die cutting was done. Wax-up was done for 3-unit FPD from lateral incisor to canine replacing canine and converting existing canine as first premolars bilaterally. Key-keyway type of semi-precision attachment was used (Sterngold, USA) [Figure 3]. The keyway of semi-precision attachment was attached distal to distal abutment, i.e., canine [Figure 4] with the help of a surveyor to keep it parallel to long axis of tooth, and casting was done. Care should be taken that the lower surface of attachment should be 0.5–1 mm away from the soft tissue to prevent soft-tissue irritation and ease of cleaning. Casting was finished and placed onto the cast back. Now, wax-up for 2-unit FPD from second premolar to first molar was done with key of semi-precision attachment attached to mesial side of second premolar pontic. Casting was done and the prosthesis was finished [Figure 5]. Metal try was taken in the patient's mouth to confirm that the accurate fit of the prosthesis and key and keyway of semi-precision attachment are seating properly [Figure 6]. After try-in, ceramic application was done. Five-unit FPD consisting of 3-unit FPD from lateral incisor to first premolar and 2-unit FPD from second premolar to first molar was cemented in the patient's mouth [Figure 7]. Group function occlusion was given on both sides, which was verified, and the patient was recalled after 1 month. After 1 year also, the patient is comfortable and is still under follow-up.
| Discussion|| |
Semi-precision attachment is an attachment that is fabricated by the direct casting of plastic, wax, metal, or refractory patterns. The semi-precision type of retainer has an advantage over the manufactured type in the fact that it is somewhat simpler to construct and hence is less time consuming and, as a consequence, not as costly. A disadvantage is that the parts do not fit together with the same degree of machined precision., Semi-precision partial dentures are retained in the mouth by means of mechanical interlocking components. A specially shaped extension of the partial denture fits into or onto a complementary receiving area or projection of a natural tooth that has been crowned. The components fit snugly and consist of a semi-rigid metal to other surface interfaces, which may also be metal or some other resilient materials such as nylon.
The indications for the use of nonrigid connector in fixed prosthodontics are as follows:
- Pier abutment: It promotes a fulcrum-like situation that can cause the weakest of the terminal abutments to fail and may cause the intrusion of the pier abutment.
- Malaligned abutment: Where parallel preparation might result in devitalization. Such situation can be solved by the use of intracoronal attachments as connectors
- Mobile teeth: Which need to be splinted together with fixed prosthesis
- Long-span FPDs: Which can distort due to shrinkage and pull of porcelain on thin sections of framework and thus affect the fitting of the prosthesis on the teeth.
The four types of nonrigid connectors are as follows:
- Dovetail (key-keyway) or tenon-mortise-type connectors
- Cross-pin and wing-type connector
- Split-type connector
- Loop-type connector.
In this case, it was decided to use the key-keyway type of semi-precision attachment and it was procured from Sterngold company, USA. This case report involves the application of key-keyway type of semi-precision attachment, which is known to reduce detrimental stresses and excessive torque on the pier abutment, thereby maintaining the periodontal health of the remaining teeth.
There is a conflict in opinion on placement site of nonrigid connector. Markley suggested placement on one of the terminal abutments and not at the pier abutment. Adams suggested placing the connector at the distal side of the pier, and if desired, adding one more at the distal side of the anterior retainer, while Gill suggested placing it at one side or both sides of the pier. Carl E Misch recommended that in conventional fixed prostheses, the “male” portion of a nonrigid attachment usually is located on the mesial aspect of the posterior pontic; whereas, the “female” portion is in the distal aspect of the natural pier abutment tooth. This prevents mesial drift from unseating the attachment. However, an implant does not undergo mesial drifting, and the nonrigid connector location is more flexible. For a natural pier abutment between two implants, a stress breaker is not indicated.
Shillingburg et al. suggested placing the connector at the distal aspect of the pier abutment. Since the long axis of the posterior teeth usually leans slightly in a mesial direction, vertically applied occlusal forces produce further movement in this direction. This would nullify the fulcrum effect and the patrix/male of the attachment would be seated firmly in place when pressure is applied distally to the pier. This position has been supported by finite element analysis study done by Oruc et al. In this case, we have placed it on the distal aspect of the pier.
In this case, group function occlusion was given on both sides as canine-guided occlusion should not be given if canine is periodontally weak, canine is missing, or canine is replaced with implant.
| Conclusion|| |
The decision to use precision attachments in partial denture design should be carefully considered. Conventional-type FPDs should be used whenever practical because of their lower cost, ease of fabrication, and maintenance and the predictability of results. However, if precision attachment FPD is the treatment of choice because of esthetics, abutment alignment, or the need for greater cross-arch bracing, it must be used with a thorough knowledge and understanding of prosthodontic principles. Intricacies and special problems associated with the precision attachments should also be considered.
It is alright to consider such sophistication where the facilities for this precise laboratory work and knowledge of using semi-precision attachment are available.
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
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]