|Year : 2015 | Volume
| Issue : 1 | Page : 36-40
Andrew's Bridge System: An Esthetic Option
Prajakta Bhapkar1, Amit Botre2, Preethy Menon2, Priyanka Gubrellay3
1 Lecturer, Department of Prosthodontics, Sinhgad Dental College and Hospital, Pune, Maharashtra, India
2 Private Practitioner, R. R. Dental College and Hospital, Udaipur, Rajasthan, India
3 Lecturer, R. R. Dental College and Hospital, Udaipur, Rajasthan, India
|Date of Web Publication||19-Oct-2015|
101, North Block, Sinhgad Staff Quarters, STES Campus, Vadgoan (Budruk), Pune - 411 041, Maharashtra
Source of Support: None, Conflict of Interest: None
Loss of teeth often results in loss of a variable amount of adjacent soft and hard tissue. Complete esthetic surgical replacement of the lost tissues is difficult and unpredictable, particularly when a greater degree of the residual ridge has been lost due to trauma, congenital defects or other pathologic process. Fixed-removable partial dentures are particularly indicated for patients with extensive supportive tissue loss and when the alignment of the opposing arches and/or esthetic arch position of the replacement teeth create difficulties for placement of a conventional fixed partial denture. This case report shows the fabrication of a fixed-removable partial denture using the Andrews Bridge philosophy wherein a removable prosthesis is retained by a bar and sleeve attachment to fixed retainers on the either side of the edentulous space. This prosthesis is designed to meet the requirements for esthetics, comfort, phonetics, hygiene, and favorable stress distribution to the abutments and soft tissue.
Keywords: Andrew′s Bridge, bar and sleeve attachment, fixed-removable partial dentures
|How to cite this article:|
Bhapkar P, Botre A, Menon P, Gubrellay P. Andrew's Bridge System: An Esthetic Option. J Dent Allied Sci 2015;4:36-40
|How to cite this URL:|
Bhapkar P, Botre A, Menon P, Gubrellay P. Andrew's Bridge System: An Esthetic Option. J Dent Allied Sci [serial online] 2015 [cited 2019 Nov 18];4:36-40. Available from: http://www.jdas.in/text.asp?2015/4/1/36/167541
| Introduction|| |
Loss of teeth is one of the natural sequelae of aging process. There are various causes of tooth loss including caries, periodontitis, trauma, and extraction as a part of surgical excision of tumors. Tooth loss results in the subsequent loss of the adjacent alveolar process and the soft tissues around it. The extent of this supportive tissue loss depends on the severity of the cause. Replacement of the lost teeth requires that the deficient supporting tissues (if any) be restored for an esthetic outcome of the resulting prosthetic replacement. These defects can be restored by surgical intervention or by artificial substitutes. Prosthodontics is the dental specialty pertaining to the diagnosis, treatment planning, rehabilitation and maintenance of the oral function, comfort, appearance and health of patients with clinical conditions associated with missing or deﬁcient teeth, and/or maxillofacial tissues using biocompatible substitutes. 
Complete esthetic surgical replacement of the lost tissues is difficult and unpredictable, particularly when a greater degree of residual ridge has been lost due to trauma, congenital defects or other pathologic process.
The prosthetic treatment options for a short span edentulous clinical situation include:
- Conventional fixed partial denture (FPD),
- Implant supported FPDs,
- Removable partial denture (RPD) or
- Fixed-removable partial denture.
Dr. James Andrews of Amite Louisiana (Institute of Cosmetic Dentistry, Amite, LA, USA) first introduced a fixed-removable prosthesis.  It is also called as Andrew's Bridge which consists of a fixed retainer and removable pontics.  The fixed-removable partial denture has a pontic assembly that is removed by the patient for preventive maintenance. The retainers are either porcelain fused to metal (PFM) or full veneer metal, which are permanently cemented to the abutments. The retainers are joined with prefabricated castable bars and then cast together, or a prefabricated metal bar is soldered to the metal copings after casting. The removable pontics are retained by a clip on the intaglio surface which fits precisely over the bar attachment. Primary indication for this restoration are cases where the abutments are capable for supporting a fixed dental prosthesis (FDP) but the residual ridge has been partially lost due to trauma, congenital defects or other pathologic process, so that a conventional FDP would not adequately restore patient's missing teeth and supporting structures.  It is also indicated when the esthetic arch positioning of the replacement teeth is not possible using a conventional FPD due to difference in alignment of the opposing arches or segmental deficiency in a particular arch.
This case report shows the fabrication of a fixed-removable partial denture using the Andrews Bridge philosophy wherein a removable prosthesis is retained by a bar and sleeve attachment to fixed retainers on the either side of the edentulous space. This prosthesis is designed to meet the requirements for esthetics, comfort, phonetics, hygiene, and favorable stress distribution to the abutments and soft tissue.
| Case Report|| |
A 35-year-old male patient reported to the hospital with the chief complaint of missing upper and lower front teeth. A complete medical and dental history was obtained. History revealed that he had met with a road traffic accident 10 years back and had multiple fractures of the middle and lower third of the face involving the maxillary and mandibular bones and loss of several anterior teeth. He was treated for the traumatic injuries, and fixation was done with metal plates and intermaxillary fixation of the teeth was done. The patient was using interim RPDs replacing the missing teeth for 10 years but was not satisfied with the esthetics and function of the prosthesis.
Extraoral examination revealed reduced upper and lower lip support and facial scars of previous injuries. Intraoral examination revealed following missing teeth: 11, 12, 21, and 22 in the maxillary arch and 31, 32, 33, and 41 in the mandibular arch [Figure 1]. There was a considerable reduction in the height and width of the residual alveolar ridge in the maxillary anterior region (Sieberts Class III).  The bony defect in the mandibular arch was not severe and could be classified as a Sieberts Class II defect. Generalized hypoplasia was seen on the teeth with brownish stains. Anterior open bite was present. 43 was malaligned and discolored with inadequate cusp tip anatomy. When viewed from occlusal aspect, there was arch asymmetry across the midline in the maxillary and mandibular arches [Figure 2]. Intraoral periapical radiographs and orthopantomographs were made. OPG shows the fixation done in the facial bones and mandible [Figure 3]. The radiographs showed good bone support around the abutment teeth (13, 23, 34, and 42).
Treatment options for the maxillary arch included implant supported FDP with autogenous bone graft, conventional FDP, a fixed-removable partial denture and a conventional RPD. Placement of implant would have required preprosthetic surgeries such as onlay grafts or alloplastic grafts possibly with soft tissue regeneration that would require months of healing period and the outcome may not have been predictable.  FDP can restore function and esthetics only to a limited extent. In the maxillary arch, the asymmetry in the arch across midline was not allowing esthetic placement of the artificial teeth without compromising the laws of biomechanics. If the teeth were to be placed along the ridge, it would not provide adequate lip support that was a primary esthetic concern in this patient. The increased bone loss would have required an increase in the length of the pontics that could have caused esthetic failure.  Therefore, the defect would have required corrections by soft tissue grafts and bone grafts to render it suitable for FDP. The conventional removable prosthesis was not satisfying patient's needs, and if not maintained properly, it would have caused decalcification and dental caries of the adjacent teeth, periodontal problems such as inflammation of the gingival tissues, etc. ,,
In prolonged denture wearers, a RPD may cause inflammation of the mucous membrane, denture induced hyperplasia due to broad coverage of the denture flanges and bone resorption.  The patient was informed about the various treatment options and after the patients approval a fixed-removable prosthesis was planned for the prosthodontic rehabilitation of the partially edentulous condition in the maxillary arch. A conventional FDP with slightly longer pontics was planned for the mandibular arch after evaluation of esthetics during speech.
- The patient was advised to discontinue wearing the previous interim partial dentures. The oral hygiene of the patient was not satisfactory, so he was prescribed oral prophylaxis and chlorhexidine mouthwash rinses.
- Diagnostic impressions of the maxillary and mandibular arches were made using irreversible hydrocolloid impression material, and study casts were poured.
- The casts were mounted on a semi-adjustable articulator with facebow transfer and in maximum intercuspation using an interocclusal record. Diagnostic wax-up was done, and a treatment plan was formulated. A mock tooth preparation was done on the study casts that revealed that intentional endodontic treatment had to be done with 13 and 42 to receive PFM restorations. 13 was planned to be restored as 12 and 34 was planned to be restored as 33 for esthetics.
- Tooth preparation was done with 13 and 23 to receive PFM crowns that will be connected with a bar attachment. Tooth preparation was done with 34 and 42 as abutments for PFM FDP replacing 31, 32, 33, 41, and 42 [Figure 4]. The gingival retraction was done using chemico-mechanical method, and final impressions were made using poly-vinyl siloxane impression material and two-stage putty wash technique.
- The prepared teeth were temporized using tooth colored self-cure acrylic resin by indirect technique. The master casts were poured using Type-IV gypsum product and were mounted on a semi-adjustable articulator.
- Wax-up was done for PFM retainers with 13 and 23, and they were connected with a prefabricated castable plastic bar attachment (OT Bar Multiuse, Rhein 83). 13 was waxed up to look like 12 for improved esthetics. 34 was waxed up to look like 33. The bar was positioned parallel to the ridge and was attached on the palatal aspect of the retainers [Figure 5]. The bar was placed such that 2-3 mm of space was left between the bar and the crest of the alveolar ridge to facilitate maintenance of hygiene by the patient [Figure 5]. The assembly was casted in cobalt-chromium alloy. Wax pattern was also done for the copings of PFM FDP replacing 31, 32, 33, 41, and 42 and was casted.
- Metal trial was done for the maxillary and mandibular prostheses [Figure 6] and [Figure 7]. Shade selection was done for matching the shade of ceramic restorations with that of acrylic denture teeth.
- Waxed up trial denture replacing 11, 21, and 22 was fabricated and adjusted to match the facial midline of the patient [Figure 8]. Wax was added to the labial portion of the denture flange for adequate lip support and esthetics [Figure 9].
- The ceramic build-up was done for the mandibular PFM Bridge and the fixed retainer part of the Andrews Bridge system and was cemented over the prepared teeth with glass ionomer cement [Figure 10].
- As 43 was discolored and slightly malaligned with an inadequate cusp tip anatomy [Figure 1] and [Figure 2], a composite restoration was done with 43 to obtain better anatomy and esthetics [Figure 10].
- With the fixed components of the maxillary prosthesis in position, an irreversible hydrocolloid impression was made, and dental stone cast was poured for the processing of the RPD.
- The waxed up trial denture was processed in heat cure acrylic resin, finished and polished and tried in patients mouth over the fixed component of the Andrews Bridge system. The undercut under the bar attachment was blocked out with wax. The clip was attached to the bar attachment and was picked up in self-cure acrylic resin into the RPD. The denture was removed, finished, and polished and it was checked for retention of the bar and clip, esthetics, and phonetics [Figure 11].
- The patient was trained to place and remove the prosthesis. The use of interdental brush under the bar attachment was suggested for maintenance of oral hygiene along with routine oral hygiene instructions. The periodic recall was emphasized to check for the success of the treatment.
|Figure 5: Prefabricated castable bar attached between waxed up copings with 13 and 23|
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|Figure 8: Waxed up trial denture for removable partial denture with 11, 21, and 22|
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|Figure 9: Wax added on labial flange of removable partial denture for lip support|
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|Figure 10: Final cementation of porcelain fused to metal fixed partial denture and fixed component of Andrew's Bridge|
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|Figure 11: Post-operative Picture: Andrew's Bridge replacing 11, 21, and 22 using bar and sleeve attachment|
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| Discussion|| |
Clinicians often come across clinical situations with localized alveolar ridge defects. It has been reported that only 9% of the patients with the anterior teeth missing between the two canines did not have ridge defects. 
The most commonly seen defects are the combined Class III defects (56% of cases), followed by horizontal defects Class I (33 % of the cases).  Vertical defects were reported to be found in 3% of the patients.  Large vertical and horizontal bone defects pose a prosthodontic challenge as it is difficult to restore esthetics and function along with the complete closure of the defect. Such clinical conditions are not successfully treated by conventional fixed or removable prosthesis.
Advantages of Andrews Bridge system:
- Andrews Bridge has both fixed and removable properties. Andrew's system provides maximum esthetics and optimum phonetics in cases involving considerable supporting tissue loss, jaw defects and when the alignment of the opposing arches and/or esthetic arch position of the replacement teeth create difficulties.
- Another favorable property of the Andrews bar system is that it can be removed by the patient thereby providing access for maintaining hygiene around the abutments and surrounding tissues. Moreover, the pontic assembly can be relined as the ridge resorbs. 
- Compared to a conventional RPD, the fixed-removable partial denture is more stable because it is totally tooth borne, and the occlusal forces are directed more along the long axes of the abutment teeth. 
- Compared to a FDP, the pontic teeth are arranged during the esthetic try-in appointment. The flange of the pontic assembly can be contoured to improve comfort, esthetics and phonetics, and to resist torque during function. Replacement of the teeth along with an acrylic denture flange is an added advantage as it does not require a separate prosthesis for the gingival defect as in the FDP.
- Andrew's Bridge has been adapted to implant prosthesis very well. ,
- Andrew's Bridge provides a better therapeutic and emergency treatment. 
- Since the prosthesis is retained by a bar retainer, the normal perception of taste is maintained as the flange need not to be extended palatally for support.
- Surgical correction of the defects using grafts and placement of implants is an expensive treatment plan for some patients. Surgical procedures also require patient's consent and compliance.
In conditions, where conventional removable or fixed prosthesis is not a feasible option as in the case presented above, a third treatment option of Andrew's Bridge can prove successful in restoring function, esthetics, speech and closure of the defect.
Limited reports of the failure of such prosthesis are found in the literature. The failures are mainly due to inadequate soldering. However, this was completely eliminated by attaching retainers to the bar in a single casting.  The patient was comfortable with the final outcome and had pleasing esthetics and phonetics.
| Conclusion|| |
Andrews Bridge system is a fixed-removable prosthesis that is indicated in patients with few missing teeth and large localized ridge defects. This functionally fixed prosthesis successfully replaces the missing teeth along with complete closure of the defect, restores speech and esthetics.
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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], [Figure 8], [Figure 9], [Figure 10], [Figure 11]