|Year : 2015 | Volume
| Issue : 1 | Page : 16-21
Tooth supported overdenture: A concept overshadowed but not yet forgotten!
Rupandeep Kaur Samra1, Shreenivas Vasant Bhide2, Chhavi Goyal3, Taranjit Kaur4
1 Department of Prosthodontics, Himachal Dental College, Sundarnagar, Himachal Pradesh, India
2 Department of Prosthodontics, Bharati Vidyapeeth Dental College, Katraj, Dhanakawadi, Pune, Maharashtra, India
3 Prosthodontist, Private Practitioner, Gurgaon, Haryana, India
4 Department of Endodontics, National Dental College and Hospital, Derabassi, Mohali, Chandigarh, India
|Date of Web Publication||7-Jul-2015|
Rupandeep Kaur Samra
House no. 10, Doctor's Colony, Bhadson Road, Patiala - 147 001, Punjab
Source of Support: None, Conflict of Interest: None
The concept of conventional tooth-retained overdentures is a simple and cost effective treatment than the implant overdentures. When few firm teeth are present in an otherwise compromised dentition, they can be retained and used as abutments for overdenture fabrication. This helps improve the retention and stability of the final prosthesis significantly. Bone is a dynamic tissue. The extraction of teeth results in the initiation of the bone resorption pattern. However, when tensile stress is received by bone, additional bone formation takes place. Such stresses occur when occlusal forces are transmitted to the alveolar bone by the periodontal ligament. This principle helps preserve bone. The concept of overdentures may not be the elixir, but it is a positive means for delaying the process of complete endentulism and helps in the preservation of bone. To top it all, it gives the patient the satisfaction of having prosthesis with his natural teeth still present. In this article, case reports with three different types of Overdentures are discussed: Overdenture with cast copings with short dowels, O-ring attachments, and a customized bar supported overdenture with copings.
Keywords: Bar supported overdenture, bone preservation, bone resorption, cast copings, O-ring attachment, tooth retained overdenture
|How to cite this article:|
Samra RK, Bhide SV, Goyal C, Kaur T. Tooth supported overdenture: A concept overshadowed but not yet forgotten!. J Oral Res Rev 2015;7:16-21
|How to cite this URL:|
Samra RK, Bhide SV, Goyal C, Kaur T. Tooth supported overdenture: A concept overshadowed but not yet forgotten!. J Oral Res Rev [serial online] 2015 [cited 2018 Nov 18];7:16-21. Available from: http://www.jorr.org/text.asp?2015/7/1/16/160172
| Introduction|| |
Preventive prosthodontics emphasizes the importance of any procedure that can delay or eliminate future prosthodontic problems and overdenture is an important part as the preventive treatment modality. A complete denture patient goes through a sequel of events like loss of discrete tooth proprioception, progressive loss of alveolar bone, transfer of all occlusal forces from the teeth to the oral mucosa and the most depressing sequel is the loss of patient's self-confidence. An overdenture delays the process of resorption, improves denture foundation area and increases masticatory efficiency. 
DeVan golden statement: "Perpetual preservation of what remains is more important than the meticulous replacement of what is missing" still rings true. Overdenture is a definitely a better option as compared to a removable complete denture prosthesis, which certainly has its drawbacks. Overdenture is one of the most practical measures used in preventive dentistry. In a 4 years study by Renner et al., it was found that 50% of the roots used as overdenture abutments remained immobile. 
According to GPT 8, overdenture is a removable partial or complete denture that covers and rests on one or more remaining natural teeth, roots, and/or dental implants; a dental prosthesis that covers and is partially supported by natural teeth, tooth roots, and/or dental implants. It is also called as overlay denture, overlay prosthesis and superimposed prosthesis.
Overdenture is indicated in patients with few remaining retainable teeth in an arch. It is also preferred in patients with malrelated ridge cases; patients needing single denture; patients with unfavorable tongue positions, muscle attachments, and high palatal vault, which render the stability and retention of the prosthesis difficult. ,,
Overdentures are contraindicated in patients with questionable oral prophylaxis, systemic complications, and inadequate inter-arch distance.
Pros and Cons of overdenture
Advantages of overdentures include preservation of alveolar bone, proprioception, enhanced stability and retention and maintenance of vertical dimension of occlusion. ,,, It is also useful for patients with congenital defects such as oligodontia, cleft palate, cleidocranial dystosis and Class III occlusion. Overdenture can be easily converted to complete denture over a period of time.
Disadvantages of overdenture include that meticulous oral hygiene is pertinent in order to prevent caries and periodontal disease. The over-denture tends to be bulkier and overcontoured Encroachment of inter-occlusal distance is another disadvantage. This treatment modality is an expensive approach with frequent recall check-ups of the patient than a conventional removable complete denture.
In overdenture treatment, the teeth are included as part of the residual ridge. The most important advantage is that the patient has the psychological benefit of having his own teeth which outweighs all the disadvantages stated.
Retentive devices included into denture teeth result in improved retention as well as support. An important periodontal requisite with over denture abutment is adequate zone of attached gingiva. ,,
Tooth-supported Overdenture treatment options are boundless and there are innumerable options to choose from for different cases.
In this paper three cases are presented where overdenture with different attachments was given as small copings with dowel, prefabricated O-ring post system, bar and copings with intraradicular post. Each case was differently selected on the base of number of abutment teeth present, their alignment and intra-arch space present.
| Case Reports|| |
A 55-year-old patient came to the Department of Prosthodontics in Bharati Vidyapeeth Dental College to get her missing teeth replaced. She had a completely edentulous maxillary arch. Mandibular arch was partially edentulous with Kennedy type I modification 1. 33 and 43 were present [Figure 1]a]. The patient gave a history of loss of her missing teeth over a period of 15 years due to multiple caries and periodontal problems. She had worn three treatment removable partial dentures during that period. No mobility and periapical pathology was noticed in the clinical and radiographical examination. The patient wanted a prosthesis with good retention as compared to her previous dentures.
|Figure 1: (a) Preoperative mandibular arch with 34 and 44 present. (b) Resin pattern preparation for coping with 34 and 44. (c) Coping cemented over 34 and 44. (d) Final maxillary impression with zinc oxide eugenol impression paste. (e) Final mandibular impression with regular body elastomer. (f) Final denture placed|
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A tentative jaw relation of the diagnostic casts was done to assess the inter-arch space. It was found to be sufficient for an overdenture with short copings but less for a bar supported overdenture. After intentional root canal of 34 and 44, they were prepared with tapered round end diamond point with chamfer finish line made subgingivally. Preparation for the post was done 4 mm short of the apical length. Custom post was prepared with the help of a trimmed matchstick with pattern resin (Duralay inlay pattern resin). The copings were dome shaped and extra pattern resin was trimmed off [Figure 1]b].
Care was taken to see if there was complete penetration into the prepared canal and no bubbles are present. These were then sprued and finally casted in Base metal alloy (Hera P, Heraenium at cobalt chromium alloys, Heraeus Kulzer). The copings obtained were checked for fit in the patients' mouth and finally cemented with glass ionomer cement [Figure 1]c]. The thickness of the copings should not be more than 1 mm.
Primary impression for the maxillary arch was made with Impression compound (Kerr Impression compound) and with alginate (Vignette) for the mandibular arch. The impressions were poured and special trays were fabricated with self-cure acrylic resin. Border molding was done for both the arches with low fusing compound. Final impression for the maxillary cast was made with zinc oxide eugenol (ZOE) impression [Figure 1]d]. Mandibular final impression made with regular body elastomer (Reprosil, Dentsply Caulk) [Figure 1]e]. Master casts were prepared by pouring the impressions in Type IV gypsum (Ultrarock, Kalabhai Karson Pvt. Ltd.)
Copings on the master cast were covered with wax and record base fabricated after applying separating media. Placement of wax over abutments prevents the fracture of the cast during removal of the temporary record base at the time of dewaxing. Occlusal rims were fabricated; maxillomandibular relations recorded and transferred onto the semi-adjustable articulator with the help of face-bow. Teeth setting was done, evaluated in the patient's mouth for phonetics, vertical and centric relation and finally esthetics. Vertical dimension was verified and centric and eccentric contacts checked. Patient's approval was taken, and the curing of the final denture was done in heat-cure acrylic resin (Lucitone199 denture base material, Dentsply, Germany) [Figure 1]f].
Another female patient aged 60-year-old, having lost her teeth because of caries over a span of 10 years wanted a prosthesis with more stability than the previous removable prostheses she had worn. Teeth 33 and 43 were present [Figure 2]a].
|Figure 2: (a) Preoperative mandibular arch with 33 and 43 present. (b) Access post system with 33 and 43. (c) Access post cemented with 33 and 43. (d) Maxillary and mandibular final elastomeric impression. (e) Nylon caps placed over the access posts. (f) Final denture placed|
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Diagnostic casts were articulated at the anticipated vertical dimension of occlusion. The tentative articulation helped in assessing the available inter-arch space, and this was found to be adequate. Proposed abutment teeth numbered 33 and 43 were prepared on the diagnostic cast, and the ability to accommodate O-ring attachments was assessed. After careful planning, a final treatment plan was given to the patient with the fabrication of a mandibular overdenture with O-ring attachment. Elective endodontics was carried out with teeth 43 and 33. Abutment teeth were prepared with a dome-shaped contour hemispherically rounded in all dimensions. The height of the abutment teeth was 3-4 mm with the finish line placed supra-gingivally. The exposed dentin of the abutment was polished and treated with fluoride varnish. Preparation for the "O-ring" direct access post was done with the primary reamer and countersink drill (AccessPost Overdenture, Essential Dental systems) [Figure 2]b]. After the required height was obtained, the access post was checked for the fit and finally cemented [Figure 2]c]. The rubber band was placed over the O-ring. Primary impressions were made (Kerr impression compound for the maxilla and Vignette alginate for the mandibular arch) and custom trays fabricated. For the maxilla, border molding was done and the final impression made with ZOE [Figure 2]d]. An elastomeric impression [Figure 2]d] was made for the mandibular arch and the casts poured in die stone. A record base with relief block-out around the attachment was fabricated. Occlusal rims were made, and face bow transfer done. The jaw relationship record was articulated over a semi-adjustable articulator. Teeth arrangement was done. After a satisfactory trial, the trial denture was invested and dewaxed. Dentures were cured and polished.
Clinically, both denture bases were adjusted to the supporting mucosa using pressure indicator paste. After the denture-base and tissue-surface adjustments were complete, then the attachments were incorporated into the denture base. Rubber band was used to cover the height of contour and the denture-base attachment, that is, the nylon caps were placed onto the abutments [Figure 2]e] and were luted chairside to the denture base using an autopolymerizing denture-base resin.
When the denture base was removed, the tissue surface was observed to evaluate the successful transfer of the female attachment process. The excess material from the access openings was removed, and the area polished.
Pressure indicating paste was used for this purpose to identify contact between the O-rings and the denture base. Finally, the mandibular denture was placed [Figure 2]f]. It had a passive fit with the simultaneous accurate contact of the denture base on the mucosa and the O-ring attachments without any rocking movement. Both the dentures were placed in the patient's mouth and checked. Patient was kept on 1 year recall.
Another patient aged 62-year-old female came to the Department of Prosthodontics came to get her missing teeth replaced. 33, 34 and 44 were present [Figure 3]a and b]. Diagnostic casts were articulated at the anticipated vertical dimension of occlusion. Vertical dimension recording was easier because of the presence of a premolar (44). The diagnostic articulation helped in assessing the available inter-arch space. Proposed abutment teeth 33, 34 and 44 were prepared on the diagnostic cast, and the ability to accommodate bar and cast copings was assessed. After careful planning, a final treatment plan was given to the patient with the fabrication of a mandibular overdenture with customized bar between 33 and 44 with copings and individual coping with dowel over 34. A bar is especially useful when abutments are misaligned or nonparallel to one another, making it harder to develop a common path of placement between the abutments and the denture base. The bar attachment provides a separate, parallel path for placement of retentive bar-clips located in the denture base. When more than two abutments were present, parallel placement of the prosthesis was difficult to achieve thus a bar attachment was a better choice. Elective endodontics was carried out with teeth 33, 34 and 44. Abutment teeth were prepared in a dome-shaped contour and hemispherically rounded in all dimensions. A cylindrical post 4 mm long with antirotation extension was prepared in the pulp canal in 33, 34 and 44. This space provided the space for short dowels cast as a part of the metallic copings. The height of the abutment teeth was 3-4 mm projecting just above the gingiva. The exposed dentin of the abutment was polished and treated with fluoride varnish. Indirect cast coping impression was made [Figure 3]c] and the cast poured in die stone.
|Figure 3: (a) Preoperative edentulous maxillary arch. (b) Preoperative mandibular arch with 33, 34 and 43 present. (c) Indirect final mandibular impression of prepared cast copings. (d) Wax pattern for bar framework with joined coping on 33 and 43 and individual coping over 44|
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A rectangular wax pattern was made for the bar framework between 33 and 44 with inlay wax (Blue inlay wax, Kamdent, United Kingdom). Individual coping was made over 34. The bar framework was made egg shaped with thinnest portion resting on the ridge (modification of Dolder bar design). An adequate gap of 3 mm was provided above the ridge for adequate clearance. Parallelism of the abutment coping was checked by the surveyor. The patterns were connected using 2 mm sprue former wax (Bego, Germany), invested, [Figure 3]d and [Figure 4]a] burnout and casting of the framework were done in Co-Cr alloy. The bar framework with stud attachments was finished and polished. It was tried in the patient's mouth, and the fit was found to be satisfactory. The bar and stud framework was luted to the abutment teeth using resin cement [Figure 4]b].
|Figure 4: (a) Investment of wax pattern. (b) Cemented bar assembly. (c) Maxillary and mandibular final impression. (d) Final denture placed|
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After the cementation of the bar framework, a final impression of the lower arch was made using regular body elastomer (Aquasil regular set, Dentsply Caulk) in a special tray. Care was taken to block the undercuts below the bar with the soft wax bat the time of impression making. The maxillary impression was made with ZOE impression paste after border molding [Figure 4]c]. A female component was fabricated as a metal sleeve to snugly fit over the bar. This sleeve was perforated to allow for the retention of the same for the intaglio surface of the denture. This sleeve was embedded in the tissue surface of the denture later.
A record base was fabricated with relief block-out. A record rim was made, and the jaw relationship recorded and transferred onto a semi-adjustable articulator.
Teeth arrangement was done. During try-in, patient's approval was taken, and the trial denture was finally processed. Relief was provided around the bar framework area so that no movement of the framework occurred as the denture base was moved slightly on and off the tissue. Pressure indicating paste was used for this purpose to check unwanted contacts. Finally, the denture was placed [Figure 4]d]. It had a passive fit with the simultaneous accurate fit of the denture base on the mucosa, and the bar supported abutments. A postoperative radiograph was taken after 1 year to evaluate the abutments. They were found to be satisfactory.
Special precautions need to be taken for care of overdentures. , Topical use of fluoride agents such as Stannous fluoride, sodium fluoride and stannous fluoride gel reduces the caries to occur. Frequent recalls help in the monitoring of overdenture's success.
| Discussion|| |
The prospect of losing all his teeth can be very disturbing for a patient. It also brings down patient's morale as it is an indirect reminder for being dependent on others and losing senescence. In such conditions, overdenture option as preventive prosthodontic treatment modality should be regularly imbibed in our dental practices because of its innumerable advantages Crum and Rooney  graphically demonstrated in a 5 years study an average loss of 0.6 mm of vertical bone in the anterior part of the mandible of overdenture patients through cephalometric radiographs as opposed to 5.2 mm loss in complete denture patients.
Miller  in his study concluded that alveolar bone resorption depends upon three variables which are:
Overdenture helps reduce shrinkage of surrounding bone and reduces pressure on the alveolar ridge.
- The character of the bone.
- The health of the individual.
- The amount of trauma to which the structures are subjected.
In case of overdenture prosthesis, proprioception is maintained,  there is the presence of directional sensitivity; dimensional discrimination; canine response and tactile sensitivity.  The average threshold of sensitivity to a load was found to be 10 times as great in denture wearers as in dentulous patients. ,
Rissin et al. in 1978 compared masticatory performance in patients with natural dentition, complete denture and over denture. They found that the over-denture patients had a chewing efficiency one-third higher than the complete denture patients. 
Overdenture with attachments can redirect occlusal forces away from weak supporting abutments and onto a soft tissue or redirect occlusal forces toward stronger abutments thereby resulting in superior retention.  Attachments are often used in overdenture construction by either connecting the attachments to cast abutment copings or intra-radicularly. Overdenture attachments are classified either as studs, which connect the prosthesis to the individual tooth or as bars which connect the prosthesis to the splinted abutment teeth. They are further classified as rigid or resilient. However, since edentulous ridges and the remaining roots are often compromised, the prosthesis that relies on resilient attachments is better able to divert occlusal forces away from weak abutment teeth. The metal O-ring attachment system is considered to be a good resilient attachment for overdentures. 
In the case reports described above, customized small coping with the intra-radicular post was selected for a case with limited inter-arch space. For the second case, access posts were chosen. Access posts occupy a small vertical space and the male units on the different roots do not require parallelism.  The ball and socket attachment of Access post allows rotation of the denture attachment. Small head of the attachment limits the amount of material that has to be removed from the denture and thus the strength of the denture is not jeopardized. The technical work can be carried out easily at chairside. ,,
For the third case, there was sufficient inter-arch space, so the use of the customized bar joint with snugly fitting metal sleeve offers increased stability and retention. It has been proved that reducing abutment to 1.5-2 mm above gingival margin reduces the crown-root ratio and thus reducing mobility by 40%.  As the bar is close to the alveolar bone, forces of mastication exert much less leverage to the teeth. The bar joint offers slight vertical and rotational movement of the denture as well as a stress breaker action. Bar exhibits more cross-arch involvement and allows occlusal forces to be shared between the abutments.  Since there was adequate inter arch space, so the thickness of the acrylic denture over the copings and bar assembly was not compromised. Customized Bar assembly calls for perfection both at the dentist and technician level, so it is challenging to execute, but the results are worth the effort.
In cases with limited interarch space, reinforcement of the denture base with metal framework adjacent to the top of the coping would be effective in reducing overdenture fracture due to reduced thickness of acrylic resin because of the bulkiness of the bar assembly.  Thus stress was reduced in the midline of the overdenture and around the copings, functional rigidity was improved. Occlusal stress to the underlying denture-bearing areas was distributed evenly.
These days implant treatment has become the norm, thus tooth supported overdentures have taken a backseat as a result of competitive (belligerent) commercialization of implants.  The success of the tooth-supported overdenture treatment depends upon the proper attachment selection for the particular case. Various factors for attachment selection include available buccolingual and inter arch space, the amount of bone support, opposing dentition, clinical experience, personal preferences, maintenance problems, cost and most important being patient's motivation. Careful selection of the strategic abutment is important. The decision must first be made to retain the teeth as overdenture abutments and then the attachments should be planned. The attitude of the patient to the treatment should be assessed. Only those who understand the limitations and benefits of attachments should be treated with attachment retained overdentures. Hence, patient selection is critical to the success of the treatment.
A tooth supported Overdenture is very much at the forefront as the treatment modality incorporating Preventive Prosthodontics concepts to the core. Let's not forget our basics rather reinvigorate them and make them a regular part of our clinical practice.
Financial support and sponsorship
Conflict of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]