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Year : 2012  |  Volume : 1  |  Issue : 1  |  Page : 25-28

An innovative method to anchor mandibular overdenture by OT Cap semiprecision attachment: A clinical report

Department of Prosthodontics, ITS Centre for Dental Studies and Research, Ghaziabad, India

Date of Web Publication21-May-2012

Correspondence Address:
Prince Kumar
Department of ­Prosthodontics, ITS Centre for Dental Studies and Research, Ghaziabad
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2278-344X.96416

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Since the establishment of implant in dentistry, the use of removable prostheses in replacing missing teeth apparently becomes less popular, still the preventive prosthodontics emphasizes the importance of any procedure that can delay or eliminate future prosthodontic problems. Most patients with removable partial or complete denture are dissatisfied with their retention and stability. Semiprecision attachments offer considerable advantages such as increased retention of a denture, preservation of teeth which are otherwise indicated for extraction, as a viable alternative to implant retained overdenture and the ability to obtain parallelism in divergent abutments. A prosthodontist who familiarizes himself with semiprecision attachments will be in a position to suggest a better treatment options in retaining teeth which might otherwise be considered for extraction or immediate implant placement. However, lack of proper knowledge, overwhelming number of attachments available in the market, multiple adjustments and repairs are making dentist reluctant to offer and provide attachment-retained prostheses to their patients. This case report describes an innovative technique for improving overall prognosis of mandibular overdenture using advanced and prefabricated housing attachment system.

Keywords: Overdenture, preventive prosthodontics, semi-precision attachments

How to cite this article:
Kumar P, Bhargava A, Gupta S, Makkar S. An innovative method to anchor mandibular overdenture by OT Cap semiprecision attachment: A clinical report. Int J Health Allied Sci 2012;1:25-8

How to cite this URL:
Kumar P, Bhargava A, Gupta S, Makkar S. An innovative method to anchor mandibular overdenture by OT Cap semiprecision attachment: A clinical report. Int J Health Allied Sci [serial online] 2012 [cited 2022 Jun 27];1:25-8. Available from: https://www.ijhas.in/text.asp?2012/1/1/25/96416

  Introduction Top

Rehabilitation of partially edentulous situations can be challenging when it is distal extension situations where a fixed prostheses cannot be fabricated. Implant retained restoration are an option but this is sometimes not possible due to insufficient amount of bone or economic reasons. [1],[2] Wearing a mandibular denture is something that most patients find hectic, especially as they get older, because neuromuscular control diminishes and with it the ability to adapt easily to something new in the mouth. In this third millennium, increasing health consciousness is observed particularly in middle- and old-aged patients and this group presents the greatest prosthetic challenge to the clinician. In such cases complete or partial acrylic dentures were largely used. They hardly offer satisfactory results regarding the retention, stability, and esthetics. Semiprecision attachment has long been considered the highest form of removable denture therapy. These attachments have been largely disregarded by most dental professionals for inconsequential reasons such as cost and reluctance of a practitioner to grasp the intricacies of its indications and applications. Semiprecision attachment retained dental prosthesis is the treatment modality that can improve patients esthetics and facilitate functional replacement of missing teeth and oral structures. In most of the clinical instances, smaller the number of mandibular teeth that remain, the more thoughtfully these teeth should be treated. When only two natural teeth remain, a method of preserving them is crucial. [3],[4] When patients present with few lasting natural teeth in their mouths screening varying degrees of overeruption, tilting, and mobility, these should not be extracted before considering the obvious advantages to the patient of retaining their roots by using precision attachments and thus the surrounding alveolar bone and soft tissue environment. [5] These retained roots can give retention, support, and stability to an overdenture and also provide proprioception which would otherwise be lost with a usual denture. The commercially available OT Cap© is an extracoronal stud attachment system that consist of castable radicular component, castable mono OT Box© and retentive caps of various rigidities. It exploits ball and socket type of attachment scheme with the male component cast with a root cap coping and directly cemented to a prepared tooth. They are used in overdentures, cast partial dentures and when connecting bars on natural teeth, roots, and implants. [6] This case report focuses on the importance and techno-clinical considerations of castable housings and retentive rings (the OT Cap Strategy) in overdenture and on abutments as an alternative method to obtain improved retention and stability in hopeless clinical conditions.

  Case Report Top

A 56-year-old female patient desiring replacement of lost "lower front and back teeth" reported to the Department of Prosthetic dentistry. On thorough intraoral examination only mandibular canine and first premolar of both the sides were present with adequate height with sound periodontal support. After reviewing the initial radiographs, the patient was referred to the Department of Periodontics for therapeutic oral prophylaxis. An orthopantomogram (OPG) and intentional endodontic treatment was advised in lower 33, 34, 43, and 44. In lieu of compromised esthetics, impaired function with existing clinical situation, it was intended to construct mandibular overdenture with extracoronal attachment. The patient rejected the options of implants retained prosthesis because of the need for additional surgery, the unacceptable duration of treatment phase and related expenditure.

Technical considerations

  1. Diagnostic impressions were made and mounted on semi adjustable articulator using a face bow.
  2. The evaluation of the existing prosthetic space for the placement of extracoronal attachment was done by making a putty matrix (Express STD Putty; 3M ESPE, St. Paul, Minn.) over the completed diagnostic wax-up.
  3. The extracoronal attachment system was selected on the basis of existing space (OT CAP© , Rhein 83 Inc, USA).
  4. The clinical crown portion of 33, 34, 43, and 44 were prepared [Figure 1] but posts were planned only for 33 and 43 to achieve cross arch stabilization in future prosthesis. The obturated root canals were explored using Peeso Reamers in a sequential manner to remove Gutta Percha 4 mm short of the apical foramen. Care must be taken while reaming else it tends to break the apical seal leading to the failure of endodontic treatment. After attaining optimum postlength and space, the castable plastic pivots posts with ball attachment (Rhein 83 Inc, USA) were placed and checked for parallelism and accurate fitting [Figure 2] and [Figure 3]. After attaining proper parallelism and fitting, an additional silicone pick-up impression was made (Aquasil Easy Mix Putty, Aquasil Ultra XLV, Dentsply Caulk, Milford, USA) with the castable pivot and ball in position.
  5. Figure 1: Tooth preparation done on 33, 34 and 43, 44

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    Figure 2: Radiographic evaluation of postlength in canines

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    Figure 3: Prefabricated pivots of 7 mm. Fitting and length and was assessed

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  6. Castings of pivots posts with copings and ball attachment were cemented on both the canines [Figure 4]. On both mandibular first premolars, conventional overdenture metal copings were fabricated and cemented with glass ionomer cement (Vivaglass CEM PL, Ivoclar Vivadent). Following custom tray border molding, final impression was made using additional silicone elastomeric impression material.
  7. Figure 4: Posts with coping and ball attachments on canines

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  8. The refractory cast obtained by duplicating the master cast over which wax pattern was fabricated, to gently enclose OT Cap which has already enclosed the ball placed over canines on the cast [Figure 5] and [Figure 6]. The wax framework of the mandibular overdenture was invested, casted, and evaluated in the patient mouth.
  9. Figure 5: Retentive rings in position and wax blockout of master cast

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    Figure 6: Wax pattern with OT Cap (Green) over canines

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  10. The mandibular occlusal rims were constructed with the metal framework incorporated in the basal part of rim as base plate followed by jaw relation, teeth arrangement, and try-in procedures [Figure 7]. In the processing phase, after flasking and dewaxing, the ball on the canines were covered with aluminum foil and blocked with plaster of paris before placing metal framework over it [Figure 8]. The maxillary complete denture was fabricated using conventional techniques. On the processed mandibular denture, retentive ring (provided separately) were placed in the space left by the OT Cap at the intaglio surface [Figure 9] and [Figure 10].
  11. Figure 7: Teeth arrangment and waxup on semiadjustable articulator

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    Figure 8: Metal denture base and retentive housing (blocked with plaster) during denture processing

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    Figure 9: Retentive rings and metal copings in position and postoperative intraoral view

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    Figure 10: Pre-and postinsertion view of patient

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  Discussion Top

In the early 20 th century Dr. Herman Chayes [7] first reported the innovation of attachments. To the late 20th century, with budding technology the attachment has been applied to the superstructure of implant. In an endeavor to improve retention and esthetics of removable partial and complete dentures, Jenkins [8] categorized them into extracoronal, intracoronal, anchor, bar and auxiliary attachments. Use of precision attachments has outstandingly enhanced the retention, esthetics, and patient comfort with less post insertion adjustments. [9] Thus, many unnecessary surgery and cutting of sound tooth for abutment preparation can be avoided in restoring missing teeth. This overdenture attachment, [9] extracoronal OT Cap, belonged to the extracoronal radicular stud attachment. They are castable attachments with elastic retention of various grades that enable it to control the flexure and construct a resilient and shock absorbing prostheses. [10] In addition to good retention, the use of this attachment enhanced the esthetics of the prosthesis compared to conventional clasps and also provided trouble-free oral hygiene maintenance. Other advantages included directing the forces toward the long axis of the tooth and better tolerance due to the reduced number of components. Due to its technique sensitivity the use of this attachment had to be planned carefully to provide effective retention and to prevent tooth movement. In this case report abutments were of adequate clinical crown height to receive attachment has provided good support and improved the prognosis of mandibular overdenture.

  Conclusion Top

Apart from improving the esthetics and retention of mandibular dentures, availability of semiprecision attachments made scheming of removable partial or complete dentures more flexible. Various cases with esthetic and retention challenges can be solved with the correct selection of precision attachments. Mandibular overdenture fabricated with precision attachments is the feasible options for patients where fixed prosthesis, implants are contraindicated. Adherence to precision techniques, proper diagnosis and periodic recall preventative therapy will result in successful treatment and preservation of the patient's existing dentition.

  Acknowledgment Top

The author would like to thank the patient for providing consent to use her photograph in this article.

  References Top

1.Palmer RM, Smith BJ, Howe LC, Palmer PJ. Implants in clinical dentistry. 1 st ed. London: Martin Dunitz Ltd; 2002.  Back to cited text no. 1
2.Sherring LM, Martin P. Attachments for prosthetic dentistry: Introduction and applications. 1 st ed. London: Quintessence Publishing Co Ltd; 1994.  Back to cited text no. 2
3.Burns DR, Ward JE. A review of attachments for removable partial denture design: Part 1. Classification and selection. Int J Prosthodont 1990;3:98-102.  Back to cited text no. 3
4.Burns DR, Ward JE. A review of attachments for removable partial denture design: Part 2. Treatment planning and attachment selection. Int J Prosthodont 1990;3:169-74.  Back to cited text no. 4
5.Preiskel HW. Precision attachment in prosthdontics. 1st ed. London: Quintessence Publishing Co Ltd; 1995.  Back to cited text no. 5
6.Attachment and prefabricated castable component. Available from: http://www.rhein83.com [Last accessed on 2011 July 11].  Back to cited text no. 6
7.Preiskel HW. Precision attachments in prosthodontics: Overdentures and telescopic prostheses. Vol. 2. London: Quintessence Publishing Co Ltd; 1985.  Back to cited text no. 7
8.Jenkins G. Precision attachments- A link to successful restorative treatment. London: Quintessence Publishing Co Ltd; 1999. p. 41.  Back to cited text no. 8
9.Feinberg E. Diagnosing and prescribing therapeutic attachment-retained partial dentures. NYS Dent J 1982;48:27-9.  Back to cited text no. 9
10.Lorencki FS. Planning precision attachment restorations. J Prosthet Dent 1969;21:506-8.  Back to cited text no. 10


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]


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