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Table of Contents
Year : 2016  |  Volume : 6  |  Issue : 3  |  Page : 141-145

Prosthodontic management of a Siebert Class III defect in mandibular anterior region with a modified Andrew's bridge

Department of Prosthodontics, KVG Dental College, Sullia, Karnataka, India

Date of Web Publication7-Mar-2017

Correspondence Address:
Manjusha Palepu
Department of Prosthodontics, KVG Dental College, Sullia, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2229-5194.201652

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The absence of teeth most often has a significant impact on the function, esthetics, and thus the psychological condition of the patients. Residual ridge resorption is most common in mandibular anterior region which poses a challenging task to the restoring dentist. Several factors should be taken into consideration before diagnosing and formulating a treatment plan. Andrew's bridge is a fixed, removable partial denture which is mostly indicated in cases where the abutment teeth are capable of supporting a fixed partial denture but the residual ridge defect in the edentulous area where a conventional fixed partial denture may not adequately restore the patient's missing teeth and the supporting structures. The purpose of this article is to describe the management of a Siebert ClassIII residual ridge defect with a modified Andrew's bridge using a bar attachment and a cast metal removable partial denture.
Clinical Relevance to Interdisciplinary Dentistry
Siebert Class III condition is most prevalent and most difficult to restore as there is severe ridge defect both vertically and horizontally. Andrew's bridge with an interdisciplinary approach results in the improvement of the aesthetic and functional aspects as well as quality-of-life of the patient.

Keywords: Andrew's bridge, fixed removable partial denture, residual ridge resorption, Siebert Class III defect

How to cite this article:
Palepu M, Nooji D, Mody P, Rao S. Prosthodontic management of a Siebert Class III defect in mandibular anterior region with a modified Andrew's bridge. J Interdiscip Dentistry 2016;6:141-5

How to cite this URL:
Palepu M, Nooji D, Mody P, Rao S. Prosthodontic management of a Siebert Class III defect in mandibular anterior region with a modified Andrew's bridge. J Interdiscip Dentistry [serial online] 2016 [cited 2023 Jun 1];6:141-5. Available from: https://www.jidonline.com/text.asp?2016/6/3/141/201652

   Introduction Top

The absence of teeth most often has a significant impact on the function, esthetics, and thus the psychological condition of the patients.[1] The teeth may be missing due to congenital defects, caries, periodontal problems, or traumatic injuries.[1] This may be followed with residual ridge resorption, which is most common in mandibular anterior region.[2] Hence, the replacement of missing teeth and the lost alveolar contour always poses several challenges to the clinician. Several factors have to be considered or evaluated before selecting an appropriate treatment option for a patient that includes age, amount of bone resorption, periodontal condition of the remaining teeth, oral hygiene, economic factors. The most common treatment options available are removable partial dentures, fixed partial dentures or implant supported fixed partial denture or fixed-removable partial dentures.[3] A proper diagnosis and a prior treatment plan play a key role in the success of any restorative procedure and yield a long-term benefit to the patient. This article describes a prosthodontic rehabilitation of a severely resorbed mandibular anterior ridge with Andrew's bridge, and thus rehabilitating esthetics, function, and comfort to the patient.

   Case Report Top

A 41-year-old male patient reported to the Department of Prosthodontics, KVG Dental College with a chief complaint of sensitivity in relation to lower front teeth and difficulty in taking cold food. Past dental history revealed that the treatment was initiated at a private dental clinic without any informed consent of the patient and without any prior intimation about the cost of the treatment procedure. Later considering his economic condition as the patient could not afford the treatment, reported to our department. Extraoral examination revealed reduced lower lip support and fullness [Figure 1]. Intraoral examination revealed that tooth preparation was done in relation to 33, 34, 35, 43, 44, and 45 for receiving fixed partial denture [Figure 2]. The teeth number 31, 32, 36, 41, 42, 46 were missing, 17, 26, 47, and 18 were grossly decayed and presence of generalized gingivitis. Radiographic findings included the loss of residual ridge both horizontally and vertically which is a Class III defect according to Siebert [4] [Figure 3]. Based on the diagnostic findings, a fixed removable partial denture was planned. The whole procedure along with advantages and disadvantages was explained to the patient, and informed consent was taken. Oral prophylaxis was done. Primary impressions were made with irreversible hydrocolloid impression material (Tropicalgin, Zhermack, Mainland, Italy) and diagnostic casts were poured, followed by face bow transfer (HANAU™ Spring Bow, Whip Mix Corporation, USA). The casts were mounted in a semi-adjustable articulator (Hanau Wide-VUE; Whip Mix Corp., Louisville, KY USA) and mock-up was done. Immediate temporization (Protemp™ 4 Temporisation Material 3M ESPE, Seefeld, Germany) was done to protect the exposed dentinal tubules. Oral hygiene instructions were given to the patient and recalled after 1 week. As there was mesial migration of 37, 47 into the edentulous space, the pontic space for 36, 46 was reduced. Hence, a cantilever was planned from 35, 45 to prevent the mesial migration of 37, 47 and also supra-eruption of the opposing teeth. The prepared teeth margins were redefined for a metal ceramic crowns on 33, 34, 35, 43, 44, 45, and gingival retraction (Ultrapak, Ultradent Products Inc., South Jordan, Utah, USA) was done and impression was made with polyvinylsiloxane (Aquasil LV, Putty Material, Dentsply, Caulk, Germany) and master cast was poured in dental stone Type IV (Kaladent, Kalabhai Karson Pvt. Ltd., Mumbai, India). Wax pattern was fabricated with blue inlay wax (Bego, USA) for the prepared teeth; cutback of 1 mm was done on all the aspects; a cutback of 1.2 mm was done on the lingual aspect with a bar of 2.3 cm length, 7 mm breadth, 1.3 mm width, which is attached according to the curvature of the arch and positioned at the centre of the pontic teeth with a 1 mm ball over the bar, and was casted in nickel chrome alloy (MeAlloy, Dentsply, UK). The metal framework [Figure 4] was tried to check for the proximal, marginal and occlusal relationship, esthetics, phonetics and proper hygienic access of the area [Figure 5]. The wax-up of the cast framework for the removable component of the Andrew's bridge was fabricated and was cast in Co-Cr alloy (Jinbego-FH, China) followed by metal trial. Shade selection for the ceramic (VITA Linearguide 3D-MASTER) and acrylic teeth (A2 Shade, Acry Rock, Ruthinium ® Group, New Delhi, India) were selected according to patient's age, sex, and personality. Ceramic firing was done on the copings and teeth arrangement for the removable component [Figure 6] was done which is followed by bisque trial to check the occlusion and esthetics and lip fullness [Figure 7]. After the patient's satisfaction, the final glazing of the fixed component and acrylization of the removable component was done [Figure 8] and [Figure 9]. Then the fixed component was luted with Type I glass ionomer cement (GIC). After the final set of GIC, the retentive nylon cap (PRECI-CLIX AXIAL CEKA Attachments) was picked up using self-polymerizing acrylic resin (DPI, India) [Figure 10]. The denture was inserted, and the patient was taught to insert and remove the denture, and oral hygiene instructions were given [Figure 11]. A recall protocol of 1 week, 1 month, and 3 months was followed to check for the adaptability and assess the success of the final prosthesis and the patient was satisfied and got adapted to the new denture following all the instructions prescribed.
Figure 1: Preoperative extraoral image showing reduced lower lip fullness and support

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Figure 2: Tooth preparation done in relation to 33, 34, 35, 43, 44, 45

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Figure 3: Radiograph revels horizontal and vertical bone loss in mandibular anterior region

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Figure 4: Metal framework with a bar, and a ball over it for the removable component

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Figure 5: Metal framework tried in the patient's mouth

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Figure 6: Ceramic fired on the fixed component and teeth arrangement done on the removable component

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Figure 7: Bisque trial of both the components to check the occlusion, lip fullness, and esthetics

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Figure 8: Glazed, acrylized and finished final prosthesis. Lingual view

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Figure 9: Final prostheis insertion

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Figure 10: Tissue surface of the removable component with the retentive clip

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Figure 11: Postopeartive (extraoral)

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   Discussion Top

High incidence of ridge deformity is seen following loss of anterior teeth (91%) which is multifactorial [2] and varies from location to location, in shape and severity. The reduced bone volume can result in altered facial features and reduced lip support.[3] Moreover, the main aim of any dentist should be the preservation of remaining tooth structure as stated by De Van.[5] Therefore, careful examination of the ridge defect and appropriate treatment plan should be decided before attempting to restore such defects. In this case as the ridge defect was Siebert Class III condition, this is most prevalent (55.8%)[2] and most difficult to restore as it must be restored both labiolingually and apicocoronally.[6]

The primary indications for this Andrew's bridge are cases where the abutments are healthy and are capable enough of supporting a fixed partial denture but a residual ridge defect in the edentulous area where a conventional fixed partial denture may not adequately restore the patient's missing teeth and the supporting structures.[7] A removable partial denture can adequately restore both the missing teeth and the supporting structures in this kind of ridge defects and can be easily used by the patient for hygienic access to abutments and surrounding areas.[8] Hence, in this case, keeping the economic condition of the patient in mind a fixed removable partial denture was planned. The bar should be rectangular with parallel sides, and the height should be more than the width and attached such that there will be a single path of insertion. A minimum of 3–4 mm occlusogingival height is necessary for proper functioning of Andrew's bridge.[9] A minimum of 2 mm vertical bar height and a occlusal clearance of about 1.5 mm is required for sufficient strength to support the removable portion of the restoration.[10] The vertical walls of the bar aid in retention of the removable prosthesis. Clearance was provided between the bar and the tissue to accomplish easy oral hygiene maintenance.

Implants in this case always have a questionable prognosis. Even mini implants or short implants also are questionable as the available bone support is compromised and both bone and soft tissue grafts in such cases have a very low success rate.[11] Another design of the prosthesis would be a complete fixed partial denture with pink ceramics which is economically not feasible.

In this case, the framework of the removable component was made of nickel chromium alloy as the wear and fracture incidence was high with acrylic partial denture which has to be replaced periodically. The framework was extended over the lingual surface of all the retainers to aid in the mechanical support and to distribute the occlusal load evenly over all the abutment teeth. As adequate inter-arch space was an available bar with a ball attachment was planned. The ball attachment over the bar is given in cases with adequate inter-arch space, and it aids in additional retention of the attachment system.

The success of any therapeutic treatment depends upon a variety of parameters which includes proper diagnosis, formulation of a treatment plan according to the diagnostic findings and careful selection of suitable patients for each treatment and implementation of indicated treatment procedure. If operator strictly adheres to these principles, any operator-induced damage can be significantly prevented.[5] Limited reports of the failure of such prosthesis are found in the literature.[5] The failures are mainly due to inadequate soldering. However, this was completely eliminated by attaching retainers to the bar in a single casting. The retentive clips have a tendency to wear over a period of time. Hence, regular recall check-up has to be done.

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.

   References Top

Gubrellay P, Gubrellay P, Vyas R. Andrews bridge system – A literature review. Int J Res Dent 2014;4:59-62.  Back to cited text no. 1
Abrams H, Kopczyk RA, Kaplan AL. Incidence of anterior ridge deformities in partially edentulous patients. J Prosthet Dent 1987;57:191-4.  Back to cited text no. 2
Muthuvignesh J, Bhuminathan S, Egammai S, Narayana DR. Improving facial esthetics with an Andrew's bridge: A clinical report. Indian J Multidiscipl Dent 2013;4:884-7.  Back to cited text no. 3
Douglas D. Pontic design. In: Rosenstiel SF, editor. Contemporary Fixed Prosthodontics. 4th ed. New Delhi: Elsevier Publishers; 2014. p. 619-21.  Back to cited text no. 4
DeVan MM. Basic principles of impression making. J Prosthet Dent 1952;2:26-35.  Back to cited text no. 5
Seibert JS. Reconstruction of deformed, partially edentulous ridges, using full thickness onlay grafts. Part II. Prosthetic/periodontal interrelationships. Compend Contin Educ Dent 1983;4:549-62.  Back to cited text no. 6
Mueninghoff KA, Johnson MH. Fixed-removable partial denture. J Prosthet Dent 1982;48:547-50.  Back to cited text no. 7
Shankar RY, Raju AV, Raju DS, Babu PJ, Kumar DR, Rao DB. A fixed removable partial denture treatment for severe ridge defects. Int J Dent Case Rep 2011;1:112-8.  Back to cited text no. 8
Christenson GJ, Guyer SE, Lefkowitz W, Malone WF, Sproull RC. Evaluation of a fixed removable partial denture: Andrews bridge system. J Prosthet Dent 1983;50:180-4.  Back to cited text no. 9
Kantorowicz GF, Howe LC, Shortall AC, Shovelton DS. Inlays, Crowns and bridges: A clinical handbook. 5th ed. Oxford: Butterworth Heinemann; 1993.  Back to cited text no. 10
Jain AR. A prosthetic alternative treatment for severe anterior ridge defect using fixed removable partial denture Andrews bridge system. World J Dent 2013;4:282-5.  Back to cited text no. 11


  [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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