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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 15  |  Issue : 3  |  Page : 495-499

Safeguarding the pier abutment


Department of Prosthodontics and Crown and Bridge, Sharad Pawar Dental College, Datta Meghe Institute of Medical Sciences (Deemed to be University), Wardha, Maharashtra, India

Date of Submission09-Jun-2020
Date of Decision05-Jul-2020
Date of Acceptance20-Aug-2020
Date of Web Publication1-Feb-2021

Correspondence Address:
Dr. Rupali Patel
Department of Prosthodontics, Sharad Pawar Dental College, Wardha, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jdmimsu.jdmimsu_168_20

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  Abstract 


In certain partially edentulous cases, the pattern of missing teeth may lead to use of fixed partial denture on pier abutment. However, it has been reported that restoration of two missing teeth and an intermediate pier abutment with a rigid FPD is not an ideal treatment option. Using rigid connector in such situation leads to concentration of stresses on pier abutment. Pier abutment in such case acts as fulcrum leading to more debonding of fixed dental prosthesis which ultimately affects the success of fixed partial denture. Non rigid connector can overcome these problems. Non rigid connector transfers shear stresses to supporting bone & permits abutments to move independently. The non-rigid connector acts as stress breaker between retainer and pontic instead of usual rigid connector. This case report presents a simple method to rehabilitate pier abutment cases.

Keywords: Pier Abutment, Non Rigid Connector, Semi Precision Attachements


How to cite this article:
Patel R, Dahane T, Khungar P, Godbole S, Kambala SS. Safeguarding the pier abutment. J Datta Meghe Inst Med Sci Univ 2020;15:495-9

How to cite this URL:
Patel R, Dahane T, Khungar P, Godbole S, Kambala SS. Safeguarding the pier abutment. J Datta Meghe Inst Med Sci Univ [serial online] 2020 [cited 2021 Feb 24];15:495-9. Available from: http://www.journaldmims.com/text.asp?2020/15/3/495/308552




  Introduction Top


The goal of restorative dentistry is to regain as much of natural form and function as possible, supplemental to preventing any further oral health issues. In terms of rehabilitation of one or two teeth, the most popular treatment modality is the fabrication of a fixed dental prosthesis. The prognosis of a fixed partial denture (FPD) relies upon multiple factors such as the abutment teeth, retainer, connector, pontic design, and the edentulous span.[1] Furthermore, biomechanical factors such as overload, torque, leverage, and flexing bring about atypical stress generation which is found to be maximum concentrated at the connector region of an FPD.[2] Hence, the selection of type of connector plays an important role.

In general, in clinical practice, the use of rigid connectors is preferred due to ease of technical and laboratory expertise and adequate force transmission across the FPD unit. Although the literature suggests that in certain atypical cases, there may arise a need to incorporate stress-breaking mechanism. This can be related to a case of pier abutment wherein a disparity occurs in the force transmission, the retentive capacity of the retainers, and the rigid connectors, thereby making its use unfeasible. A pier abutment or intermediate abutment, as stated in Glossary of Prosthodontic Terminologies, 9th Edition GPT-9, is “a natural tooth located between terminal abutments that serve to support a fixed or removable dental prosthesis.”[3]

Markely et al. described “The broken stress principle” which stated that stress breakers act as safety valves against the tremendous leverage forces created by the rigid attachment between two or more teeth.[8] Progress in this area leads to the development of nonrigid connectors for the ease of incorporation of this stress-breaking mechanism. Nonrigid connectors function as a safety valve between the components so that the force transmission can be balanced throughout the FPD without debonding itself in such cases.


  Case Report Top


A female 40 years of age came to the Department of Prosthodontics, complaining of difficulty in chewing and unpleasant esthetics. Clinical examination revealed missing teeth 15 and 17 [Figure 1] and [Figure 2]. Radiographic diagnosis revealed the presence of adequate bone support with all the teeth; hence, they can be used as abutments.
Figure 1: Intraoral maxillary arch

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Figure 2: Intraoral mandibular arch

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The patient denied implant as the treatment due to surgical intervention and economic constraints. Therefore, restoration with partial fixed dental prosthesis with a nonrigid connector was selected.

The following steps were followed:

  • Teeth were prepared for porcelain fused to metal prosthesis on right maxillary canine and second premolar with equigingival margins with shoulder finish line in order to enhance the esthetics [Figure 3]
  • Right maxillary second molar was prepared to receive a metal crown prosthesis with supragingival margin and chamfer finish line
  • Impressions were made after gingival retraction using retraction cord with elastomeric impression material following two-step putty was technique
  • Bite registration material was used to obtain interocclusal record
  • Tooth-colored autopolymerizing acrylic resin was used to fabricated provisional restoration which was cemented with noneugenol temporary cement
  • After retrieval of the master cast, die cutting and die ditching were done, followed by mounting of the casts onto the articulator using interocclusal record
  • Wax pattern was build up such that after the waxing the teeth that are canine and both the premolars, a recess was cut for the female portion to fit the prefabricated plastic dovetail on the distal aspect of pier abutment [Figure 4]
  • Position and parallelism of the dovetail were determined by surveying the casts. Both the parts were separated away, and the inside of the female patter was kept free of wax [Figure 5]. Metal try-in of the anterior segment along with the female part was done after casting to verify proper seating, and the excess was trimmed according to occlusion [Figure 6]
  • The wax pattern for molars was then fabricated after approximating the male part and the casted female portion. The pattern was then casted [Figure 7]
  • Seating of the components was verified. Ceramic layering was done onto the canine and the premolars [Figure 8]
  • The anterior segment with keyway was cemented first, followed by the posterior segment with key using glass-ionomer cement [Figure 9] and [Figure 10].
Figure 3: Tooth preparation

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Figure 4: Wax buildup

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Figure 5: Casting of metal framework

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Figure 6: Metal try-in

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Figure 7: Fabrication of matrix and patrix

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Figure 8: Ceramic buildup

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Figure 9: Final prosthesis

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Figure 10: Postcementation intraoral image

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The patient was guided regarding the use of dental floss and interdental brush, and oral hygiene instructions were emphasized. Follow-up was scheduled after a week for assessment of oral hygiene status.


  Discussion Top


Traditionally, the use of rigid connectors provides an adequate amount of stability and strength to the fixed partial prosthesis. It minimizes the atypical stresses auxiliary with the restoration, therefore, improving the prognosis and longevity of the prosthesis. However, rigid connectors may not be applicable in all clinical situations. In the case as discussed above, that is an intermediate abutment, difficulties arise due to curvature of arch, the buccolingual movement of anterior teeth with respect to posterior teeth. This tooth movement may be associated with various amount of forces, and it has been stated that these forces are directed toward the terminal retainers causing the central abutment to act as a fulcrum, leading to the failure of the prosthesis. It may cause intrusion of the pier abutment, and caries due to marginal leakage are likely to become more extensive before discovery.[4]

For even distribution of forces, therefore, a requirement of stress breaker arises. The stress-breaking mechanism, as described by Markely et al. in 1951, theorized that the stress breaker acted as a safety valve that would prevent the concentration of forces along the abutment.[8] It aids in transmitting the shear stresses to the supporting periodontium instead of localizing them in connectors. Furthermore, it minimizes the mesiodistal torquing of abutments and permits their independent movements.

Different types of nonrigid connectors used currently include “the tenon-mortise, the cross-pin and wing, and the split pontic.” The tenon-mortise or the keyway type of pontic is the most frequently used type of nonrigid connector.[5] The stress-breaking mechanism provided by the connector prevents transmission of forces solely along the intermediate abutment. The connector equalizes the forces by transmitting it to the periodontium instead of directing it in the connectors, thereby minimizing the mesiodistal torquing of abutments. It helps in compensating for the difference in the resistance and retention form between the abutments. The mechanism of the connector along with its design and passive fit is crucial for the prognosis of a long-span FDP.

Sciffelger et al. compared the accuracy of multiunit one-piece casting. The greatest discrepancy was seen at the mesiogingival surface of the anterior retainer and the distolingual surface of the posterior retainer. Seating of the casting improved after sectioning.[8] Determination and designing thus should be done keeping these observations in mind.

Ideally, according to Shillingburg, the keyway should be placed on the distal aspect of the intermediate abutment. The reason being that the posterior a slight mesial inclination of the posterior teeth has been observed upon application of occlusal load.[6] This would lead to enhanced seating of the key in the keyway the moment occlusal loading occurs. On the contrary, if the keyway is planned on the mesial aspect, the forces will tend to dislodge the key from the keyway leading to chances of fracture of the retainer assembly. This theory is supported by findings of a finite element analysis done by Oruc et al. They observed the decreased stress concentration along the pier abutment with the help of a nonrigid connector placed distally onto the intermediate abutment.[7] Other authors too have advocated the use of nonrigid connector along the distal aspect and, if need be, making the use of an additional retainer on the anterior retainer distally [Figure 11].[9],[10],[11],[12],[13],[14],[15],[16],[17]
Figure 11: Postcementation intraoral image in occlusion

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  Conclusion Top


The use of nonrigid connector in case of pier abutment aids in elimination of the load and fulcrum-like situation. Other forms such as precision and semi-precision attachments provide room for slight movements that could prevent the loading of the pier abutment, thereby improving the longevity of the prosthesis.

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 Top

1.
Kuruvila A, Joseph S, Jayalekshmi NL, Menon SK. The key to the management of pier abutment: An alternative approach. J Int Oral Health 2017;9:4.  Back to cited text no. 1
  [Full text]  
2.
Akulwar RS, Kodgi A. Non-rigid connector for managing pier abutment in FPD: A case report. J Clin Diagn Res 2014;8:ZD12-3.  Back to cited text no. 2
    
3.
Aidsman K. The Glossary of Prosthodontic Terms. J Prosthet Dent 38:66-109.  Back to cited text no. 3
    
4.
Nisal S, Banik M, Gade J, Atulkar M. Management of pier abutment using non rigid connector: A case report. Int J Oral Health Med Res 2016;2:4.  Back to cited text no. 4
    
5.
Hazari P, Somkuwar S, Yadav N, Mishra S. Different techniques for management of pier abutment: Reports of three cases with review of literature. Arch Med Health Sci 2016;4:89.  Back to cited text no. 5
  [Full text]  
6.
Shillingburg JR, Herbert T, Sather DA, Wilson JR, Edwin L, Cain JR, et al. Fundamentals of Fixed Prosthodontics. Quintessence Publishing Co, Inc.; 2012.  Back to cited text no. 6
    
7.
Oruc S, Eraslan O, Tukay HA, Atay A. Stress analysis of effects of nonrigid connectors on fixed partial dentures with pier abutments. J Prosthet Dent 2008;99:185-92.  Back to cited text no. 7
    
8.
Miles Marki EY. Broken-stress-Pinciple and Design in Fixed Bridge Prosthesis; Comparison of the Accuracy of Multiunit one-Piece Casting; 1985.  Back to cited text no. 8
    
9.
Venkataraman K, Krishna R. The lone standing abutment: A case report. Int J Appl Den Sci 2016;2:20-3.  Back to cited text no. 9
    
10.
Banerjee S, Khongshei A, Gupta T, Banerjee A. Non-rigid connector: The wand to allay the stresses on abutment. Contemp Clin Dent 2011;2:351-4.  Back to cited text no. 10
[PUBMED]  [Full text]  
11.
Savion I, Saucier CL, Rues S, Sadan A, Blatz M. The pier abutment: A review of the literature and a suggested mathematical model. Quintessence Int 2006;37:345-52.  Back to cited text no. 11
    
12.
Pandey P, Mantri SS, Deogade S, Gupta P, Galav A. Two part FPD: Breaking stress around pier abutment; 4.  Back to cited text no. 12
    
13.
Kambala SS, Borle RA, Rajanikanth K, Jaiswal T, Dhamande M. Evaluating the Color Stability of Ocular Prosthesis after Immersion in Three Different Immersion Media: An in Vitro Study. J Int Soc Prev Commun Dent 2020;10:226-34. Available from: https://doi.org/10.4103/jispcd.JISPCD_405_19. [Last accessed on 2020 Jan 15].  Back to cited text no. 13
    
14.
Shraddha R, Kambala S, Godbole S, Borle A, Jaiswal T. Comparative Evaluation of the Retentive Qualities of Three Different Post Systems Used for Endodontically Treated Teeth for Providing Restoration - An in Vitro Study. J Evol Med Dent Sci 2019;8:3754-8. Available from: https://doi.org/10.14260/jemds/2019/813. [Last accessed on 2020 Jan 15].  Back to cited text no. 14
    
15.
Aishwarya B, Deolia S, Ali SS, Gupta A, Reche A, Nimbulkar G. Assessment of Association Between Tooth Morphology and Psychology. J Clin Diagn Res 2020;14. Available from: https://doi.org/10.7860/JCDR/2020/42560.13504. [Last accessed on 2020 Jan 15].  Back to cited text no. 15
    
16.
Vilas GP, Dhamande MM, Kharpate S, Kambala S. Impact of Storage Environment and Temperature on Dimensional Stability of Alginate Impression. J Evol Med Dent Sci 2019;8:3994-96. Available from: https://doi.org/10.14260/jemds/2019/863. [Last accessed on 2020 Jan 15].  Back to cited text no. 16
    
17.
Sweta KP, Agrawal R, Belkhode V, Nimonkar S, Borle A, Godbole SR. Perception of Buccal Corridor Space on Smile Aesthetics among Specialty Dentist and Layperson. J Int Soc Prev Community Dent 2019;9:499-504. Available from: https://doi.org/10.4103/jispcd.JISPCD_2_19. [Last accessed on 2020 Jan 15].  Back to cited text no. 17
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]



 

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