Kavita H. R.a , G. N. Anandakrishnab , K. Shwetac
How to CITE:
Kavita HR, Anandakrishna GN, Shweta BK, Rehabilitation Of Edentulous Mandibular Arch With Implant Retained Overdenture – A Case Report. J Pak Dent Assoc. 2012;21(4):248-251.
patients traumatic injuries offer considerable challenges to their restoration of aesthetics and function. this article presents the rehabilitation of one such patient maxillary conventional complete denture and an implant- supported mandibular overdenture. The selection of the removable implant prostheses was based on the extremely unfavourable maxillary to mandibular anterior bone height ratio of 1:4.
It is “If tooth is lost nothing is lost if bone is lost everything is lost” indicating that bone support becomes crucial and determining factor in the success of treatment. In fact, the very first indication and the origin of implant dentistry has been the addressing of the problem associated with the wearing of mandibular complete dentures especially attributed to reduced ridge height. Implant could enhance retention and stability in cases presenting reduced potential for retention and stability
because the unfavourable ratio relating reduction in anterior bone height between the maxillary and a mandibular anterior ridges.1,2
Skillful clinical treatment procedures and technical effort for using implant prosthetic treatment, however, are required1. It is certainly one of the most challenging and expensive reconstruction to restore the edentulous mandible. However, it may be contraindicated in specific cases where replacement of lost hard and soft tissues to provide support to the facial tissues by the buccal prosthesis is of utmost importance. The treatment alternative has been described by Zitzmann et al., who placed two implants in the canine region in U-shaped mandibular arch and straight bar can be ideally positioned above the alveolar ridge 3,4.
In such a scenario implants have become a boon in treating patients with various and complex needs not withstanding the underlying bone condition as a limiting factor.
The treatment design mainly used for restoring the edentulous mandible is combined with implant-retained and soft-tissue supported overdenture. The decision making process is determined by patients expectations and their financial means and by clinical factors such as the anatomic and morphologic conditions of the mandibular bone, the quality and the quantity of the soft tissue and bone and the shape of the alveolar ridge. When a treatment plan has been made and the patient agrees with the advised treatment option, the several clinical and technical factors must be considered to achieve an optimal aesthetic and a functional result 3, 5.
A 35 year old patient reported to the Department of Prosthodontics for the prosthetic rehabilitation of maxillary and mandibular edentulous ridges with the chief complaint of difficulty in chewing and speaking.
Patient had a history of road traffic accident six years back resulting in the loss of all remaining teeth in both jaws. Medical history was non-contributory with patient not on any medication. Extra oral examination revealed reduced vertical dimension. This was assessed by clinical examination of the patient without the prosthesis where, the chin appears close to the nose. Further findings were hollow cheeks, unsupported lips and mild distortion of speech articulation on sibilant sounds. General physical status was normal. Intra oral examination revealed U-shaped, well formed maxillary and mandibular arches, fissured tongue and adequate saliva flow. Routine investigations like urine and blood examination were carried out and OPG was taken. Diagnosis was based on the OPG, bone mapping and blood investigations. There was a completely edentulous maxillary and mandibular arch with a D2 type of bone, bone height of 15 mm and width of 5 mm. Treatment plan included maxillary conventional denture and mandibular implant over denture. The treatment plan was selected after informing and obtaining consent of the patient. The treatment plan included conventional denture which was fabricated one month prior to implant surgery for the assessment of the patient response. . The patient was instructed to use the denture for one month. The implant site was selected based on available bone in the anterior mandible which was divided in to a five equal column of the bone serving as a potential implant sites labeled as A, B, C, D & E starting from patient right side according to St Louis (1999) where acrylic denture base was used as surgical stents.
Root form endosteal threaded implant (Nobel biocare) with a length of 13 mm and width of 4.3 mm were selected. Implant site were selected at B and D positions where patient’s occlusal vertical dimension determined the correct tooth position for the final prosthesis.
1. Impression was taken with alginate (Zelgan, Dentsply, India) impression was poured with type two plaster, cast was retrieved and a surgical guide template was prepared with cold cure acrylic (Dental Product of India – RR cold cure, Manufactured in India)
2. Patient was prepared for the implant placement procedure. Inferior alveolar nerve block was given. A crestal incision with a vertical relieving incision for adequately exposing the operating field was placed. Pilot drill followed by series of end-cutting implant drill to gradually increase the diameter of osteotome site was used. Implant placement was checked by parallel gauges (Figure. 1).
Osteotome was prepared, irrigated with saline. Implant fixture was placed and self threaded implant was screwed into position and cover screw was placed, the flap was closed to cover the fixture with a simple continuous suture.
3. After a week suture was removed and several recall visits were carried out up to three months.
4. Three months after placement, the implant fixture site was located with probe and the cover screw was replaced with healing screw, patient is recalled after a week.
5. PROSTHETIC PHASE – The preliminary impression was made with alginate (Zelgan, Dentsply, India). Impression was poured with hydrocal (Goldstone, Asian Chemicals INDIA). The cast was retrieved and a customized impression tray with full spacer and two vertical struts was made (Figure 2).
6.Open tray impression procedure was followed (Figure 3), which included border molding with putty material, followed by secondary impression with polyether, medium body impression material (Impregum penta soft; 3m ESPE Ag Seefeld, Germany). the transfer coping loosened with hexdrive. hydrocal (Goldstone, Asian Chemicals) was used to pour the impression. Denture bases with occlusal rims were fabricated on the casts.
7. Jaw relations were recorded and verified. Mounting was done and the teeth arrangement was completed.
8. Try in was carried out, adjustments were made and then processing of denture was carried out by heat cure resins (Dental Products India, India).
9. Denture insertion was carried out prior to hader bar fixation in order to evaluate the over extension of denture, patient was recalled after 24 hours evaluated no soft tissue changes were found. Hader bar metal frame work, which was fabricated with Co-Cr alloy was attached to the implant fixture by screws at B and D position (Figure 4). The clip was attached to denture base by direct method using cold cure acrylic resin (Dental Prodycts of India-RR Cold Cure, India) 3,4.
The patient was educated and motivated regarding the maintenance of implant and denture and importance of recall visits1-4,6-8,10,11 (Figure 5 & Figure 6).
It is pertinent at this point to discuss the root form endosteal threaded implants with a length of 13 mm and width of 4.3 mm. Integral to the treatment modality advocated by Ledermann et al is the cross arch splinting of the inter foraminal implants by means of fixed Hader bar, after implant placement. This serves to limit the micro motion of implants that would be deleterious to successful osseointegration. The over denture house clips, Hader bar joint permits the rotational movements between sleeve and bar. The challenge comes from fabricating a bar that fits passively so that it prevents undesirable stresses on the implant and screw securing the bar.
In case of mandibular arch the prosthesis has poor anterior and good posterior support, it rocks back and front. This rocking action increases the stress on the oval denture component and bone implant interface. Hence the anterior forces should be resisted by implant bar attachment whereas posterior forces can be directed on the soft tissue area such as buccal shelf. The bar attachment is more retentive than the ball or magnets. It is also stated that the minimal maintenance was required for bar-clip attachment system and prosthesis movement is reduced considerably by the attachment.
The interval between implant placement and loading was approximately 3 months. This was to allow osseointegration, prosthetic convenience and to ensure the success of the prosthesis. As advocated by Joanne N. Walton bar-clip implant overdenture is a significantly more successful prosthesis, which requires less technical maintenance1,5,6.
Functional and esthetic impairment cannot be fully compensated by implant retained prosthetic rehabilitation, but the success of bar and a clip attachment could be advantageous for implant overdenture with regards to increased stability and retention of mandibular denture and for long term success of the prosthesis.
“Smiling is sign of physical and mental well-being”. Many patients can smile unrestrainedly after implant overdenture.
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