Medical knowledge | Dentistry » George Bureau - Tooth supported, stud retained prostheses, three case reports

R E M O V A B L E AB RO S TS H O D O N T I C S P R OR E SM TO HVO D LOE NP T I C Tooth-supported Stud-retained Prostheses: Three Case Reports GEORGE P. BUREAU Abstract: The use of teeth as overdenture abutments is a common form of treatment. However, most roots are used only for support. Simple stud precision attachments will also aid the retention of the prosthesis. This article presents three different cases where studs have been used to help retain removable prostheses. Dent Update 2003; 30: 389–396 Clinical Relevance: The use of stud precision attachments to retain removable prostheses is beneficial to the patient, reducing the need for so many clasps. T he use of tooth-supported overdentures is a common form of treatment. An overdenture may be defined as ‘a denture the base of which covers one or more prepared roots or implants’.1 This article will use the term overdenture to refer to tooth-supported prostheses and not implant-supported prostheses which are not within

its scope. There are many documented advantages to the retention of roots for supporting a denture:2 l l l l Proprioceptive feedback; Maintenance of alveolar bone; Support; Retention (with the aid of precision attachments); l The psychological aspect of retaining teeth; l Tactile sensitivity discrimination. George P. Bureau, MClinDent, BDS, FDS RCS, MRD, Clinical Demonstrator, Department of Conservative Dentistry, GKT Dental Institute and Specialist in Prosthodontics in Practice, 82 Berners Street, Ipswich, Suffolk IP1 and 21 Wimpole Street, London W1M. Dental Update – September 2003 However, there are disadvantages of using teeth for overdentures: l l l l Plaque retention; Secondary caries; The need for endodontics; Cost, especially with precision attachments; l Bulk of attachments and tissue undercuts. The long-term success of using teeth as overdenture abutments has been well documented.3,4 Toolson and Taylor3 showed that, over 10 years, 66 out of 77 abutments survived and,

of the 11 that failed, six were due to secondary caries. Hence caries control is very important in the assessment of overdenture abutments. Crum and Rooney4 undertook a study with two groups of men. The first group were provided with complete upper and lower prostheses and the second had a complete upper and lower overdenture retaining the canine roots. Over a 5year period there was a loss of 52 mm of alveolar bone in the former compared to 0.6 mm in the latter group Precision attachments provide direct retention for the prosthesis. They consist of two parts, one is attached to the abutment tooth and the other to the saddle of the prosthesis. A simple classification and benefits can be seen in Table 1. There have been no real studies on the success of stud or other attachments. Various review articles have shown the different systems available.5,6,7 The important aspect is that the patient is well motivated, oral hygiene is maintained and regular reviews of the abutments is

undertaken. The objective of this paper is to describe the technique and benefits of prescribing stud precision attachments to aid retention and support in a variety of removable prostheses. Figure 1. Provisional bridge a b Figure 2(a, b). Pre-op radiographs 389 R E M OVA B L E P R O S T H O D O N T I C S Type Description Advantages Disadvantages Intracoronal Usually slot (female) within the crown of the abutment and the male attachment in the prosthesis. Good retention. Provides bracing and support. Good for bounded saddles. No need for clasps. Aggressive preparation of abutments to allow room for attachment Wear. Cost. Not used in free-end saddles. Extracoronal Attachment joined externally to linked crowns on abutment teeth. No space required within abutment. Stress breaking design. Good for free-end saddles. Good appearance. Must have well supported teeth due to large loading outside long axis of teeth. Technical & clinical skill. Cost. Must link crowns –

oral hygiene difficult. Stud Stud attachment with diaphragm on root surface. Good support & retention. Favourable crown/root ratio. Psychological aspects. Avoid anterior clasps. Space for attachments. Maintenance - including adjustment/replacement of female matrices. Cost. Plaque control must be good. Bar Bar attached to gold copings on abutment teeth. Bar joints allow some movement; bar units allow no movement. Splint teeth/roots. Good retention & stability Cost. Only used in complete denture/extensive partial. Technical expertise required. Table 1. Classification of precision attachments and benefits CASE 1 This 55-year-old gentleman was referred by the GDP and treated in practice. The treatment was a mandibular complete overdenture. It was decided to place the attachments to aid retention as the patient had never worn a removable prosthesis. Examination He presented with just the 3| and |3 remaining in the lower arch supporting an acrylic provisional bridge

(Figure 1). This had been in place for over six months and he required a definitive treatment. There were no probing depths, although there had been some attachment loss and plaque control was good. In the maxilla, there was 6| to |6 present which had been restored by crowns and bridges that also needed replacement. there had been no signs or symptoms of failure. With the disturbance of the coronal seal there is always a chance of re-infection of the system. However, there were and have been no problems in this case. In an ideal world, the root treatments would have been redone first. The first two options were excluded owing to the fact that the roots were short, and to retain a bridge or crowns and a partial denture would place unfavourable stresses that may lead to their early loss. a bilateral free-end saddle partial denture. 2. Single crowns on the 3| and |3 and a partial denture. 3. An overdenture with or without attachments. 4. An implant and tooth-supported fixed or removable

prosthesis. After discussion with the patient, he was adamant that he did not want the surgery involved in the provision of implants. He also did not want any re-root canal treatments. Although the root treatments were not ideal, a b Radiographic examination Long cone periapicals of the lower canine teeth revealed that both had been root treated (Figure 2a, b). There were no signs of infection or periapical areas and the teeth had been symptomless for many years since the treatment. c Figure 3. (a) Pick-up impression taken in Impregum; (b) with the copings and dies in place. (c) The master model Treatment options 1. A fixed-fixed conventional bridge and 390 Dental Update – September 2003 R E M OVA B L E P R O S T H O D O N T I C S prosthesis made in practice. a b Examination The teeth present were 7-1| 13(root)5. The 321 | 123 were present. The |3 was open to the oral environment and the |5 had a ‘composite crown’ in place. She was wearing a small cobalt chromium

partial denture that had poor support and retention. d c Radiographic examination A long-cone periapical radiograph of the |3 revealed that the tooth had previously been root canal treated. Figure 4. (a) The Dalbo studs in situ (b) The female matrices (c) The completed prosthesis (d) X-ray of stud in situ. Treatment The teeth were prepared for posts using the Parapost system (Coltène, Whaledent Inc.) within the confines of the gutta percha. The crown/root ratio for overdenture attachments is more favourable than postretained crowns. Therefore, with some coronal tooth tissue remaining, this warranted the use of shorter posts in this case. The studs were made from gold alloy with the attachments soldered to a domedshaped coping. These were tried in the mouth for integrity of fit. A ‘pick-up’ impression was then taken in a special tray made with correct extension for a complete denture. (Figure 3a, b, c) The prosthesis was then completed in the usual manner until patient and

operator were happy. The prosthesis was then heat-cured with the female matrices in place and an appropriate spacer. The copings were cemented into place and a check record was taken and the occlusion altered as necessary (Figure 4 a–d). Treatment options The two main options were to make P/P prostheses or to consider implantsupported restorations. The options for the |3 were to cover the root face and use as an overdenture abutment, or to re-root treat and place either a post crown or a precision attachment. The decision was made to use the tooth to help support and retain a partial denture as effectively there was a long free-end saddle. The radiograph of |5 (Figure 5) showed the pulp chamber The prosthesis has been in function for 18 months now and, although the patient knows that the obturation of the two lower canines is not ideal, there have been no problems. CASE 2 This 60-year old lady was referred for treatment. She had a partial maxillary a c b d Review The patient

has been pleased with the treatment and the retention of the prosthesis is good. The oral hygiene and dietary advice with regard to caries control was reinforced. Routine maintenance was made every three months with plaque control and scaling. 392 Figure 5. (a) Root-treated |3 (b) Stud in place (c) The Dalbo attachment (d) The Dalbo stud on working model. Dental Update – September 2003 R E M OVA B L E P R O S T H O D O N T I C S a and treated at the hospital. He was treated by a Kennedy Class 4 partial denture replacing the 54321 | 12345. b Examination c The patient had 6321 | 1236. In the lower arch he had 65321 | 123468 (Figure 8). There was severe wear on all the anterior teeth which had an aetiology of attrition and erosion. The predominant factor was parafunction, especially on long journeys in the HGV which the patient drove for work. The erosion was investigated using a 24-hour gastro-oesophageal test but this was negative. However, he consumed a large amount of

carbonated drinks which, after advice, he subsequently reduced. Radiographs revealed root canal therapy had been undertaken in the maxillary incisors. d Figure 6. (a) Pick-up impression (b) Master die in place (c) Working model (d) Space with female matrix in place. obliterated and there was no remaining clinical crown. Therefore, this tooth was left alone with the design of the denture allowing the tooth to be added. Treatment The |3 was re-root treated. The root canal was then prepared for a post using the Parapost system (Coltène, Whaledent Inc.) An impression was made for an indirect post and core onto which the Dalbo stud attachment was soldered (Figure 5a–d). The space was assessed to ensure that it was adequate and a pick-up impression was taken with addition cured silicone. The master die was placed in the impression for the working cast to be made (Figure 6). The usual stages of partial denture construction were carried out and, on heat curing the acrylic, the female

matrix was incorporated into the resin. There was just sufficient space for the attachment in conforming to the existing occlusal vertical dimension. The rest on the distal of the |5 was not part of the original design but was left as there was no real force being exerted on this tooth. A small bar was extended from the major connector to retain the acrylic resin. A metal backing to the denture tooth would have been preferable but there was limited space available. The Dental Update – September 2003 completed partial denture can be seen in Figure 7. Treatment Options The treatment options were to restore the anterior teeth at increased vertical dimension by using post-crowns and a partial prosthesis, or to restore using a partial overdenture. Owing to the history of parafunction and the fact that he was unlikely to be able to stop, it was decided to make a partial overdenture. The occlusal vertical dimension was increased a significant amount. It was therefore important to maximize

the tooth support to enable the patient to tolerate this. Review The patient took some time to adjust to wearing a larger span partial denture but was pleased with its appearance and retention. To date it has been in situ for a year with no major concerns. CASE 3 This 50-year-old gentleman was referred a b c Figure 7. (a) Partial denture in situ (b) Frontal view. (c) Close up of attachment and prosthesis. 393 R E M OVA B L E P R O S T H O D O N T I C S psychological aspects of patients losing teeth should not be underestimated and has been well documented.7 The retention of alveolar bone is also an important factor. This is especially so if a complete denture is opposed to a natural dentition or fixed prosthodontics, as in Case 1. The stud attachments that were used provide good retention as well as support. This negates the need for clasping anterior teeth which detracts from the appearance, as in Case 2. There is an added expense in the cost of endodontics (if not already

carried out) and the cost of the post/diaphragm/attachment. Therefore, careful selection of abutments is important. The first decision to be made must be whether to retain the teeth as overdenture abutments and then to assess whether attachments can be used and will be beneficial. The abutments should have the following qualities: a Figure 8. (a) Patient pre-op (b) Occlusion (c) Maxilla. (d) Mandible b c d Treatment Review The upper canines were root treated and the root canals prepared for posts using the Parapost system (Coltène, Whaledent Inc.) The upper incisors were smoothed and sealed with resin-modified glass ionomer cement. An impression was taken with polyether impression material (Figure 9). The posts/diaphragms were then cast in gold alloy and the studs soldered to the diaphragms. These were tried in the mouth to check for accuracy and then a pick-up impression using a special tray was made. In this case, analogues of the abutments were placed into the impression and

the master cast made (Figure 10). The stages in partial denture production were then undertaken in the normal way. The tooth set up was finalized before the cobalt chrome framework was made for metal backings to protect the denture teeth. The patient was instructed to wear the prosthesis at night to protect the attachments. He was shown how to clean the prosthesis with a toothbrush only, and the importance of keeping the rest of the teeth clean was impressed upon him (Figure 11). The patient successfully wore the partial denture and tolerated the increase of vertical dimension without a problem. There were some signs of wear of the acrylic but the prosthesis was still functioning well after two years. The chances are that the acrylic and/or denture teeth will need to be replaced or the prosthesis remade as the wear continues. An alternative design would have been to extend the metal connector onto the posterior occlusal table to prevent this. 394 l little or no mobility; l good root

length with little attachment loss; l no untreated periodontal disease; and l be able to be successfully root canal treated. The prognosis of other remaining teeth, the caries susceptibility, and patient attitude to treatment should be assessed. Another important aspect of the treatment is the space requirement. From the root face, the precision attachment including female matrix is about 3 mm (Figure 6). A minimum of 1 mm of polymethylmethacrylate is required and so 4 mm total space is needed. In case 2, there was only just enough room and so, on clinical examination, emphasis on space requirement is an important factor. If the acrylic is too thin it will fail mechanically. DISCUSSION The use of roots as overdenture abutments is beneficial to the patient. The a b Figure 9. Post impression Dental Update – September 2003 R E M OVA B L E P R O S T H O D O N T I C S a b d c Figure 10. (a) Stud (b) Stud with female component (c) Pick-up impression (d) Master cast a b c d

The female attachments can be cured into the denture in the laboratory or at the chairside. The former is preferable but the latter may be required in an emergency. The main problem to prevent at the chairside is to make sure acrylic does not flow inside the female attachment and ‘lock-in’. Therefore, a small amount of acrylic resin should be used initially to hold the attachment and then the prosthesis removed from the mouth and more added. The female matrices may need to be activated or deactivated. There are special instruments for this that ‘crimp’ the sections together or separate them. It may be necessary to activate at the fit or at subsequent review appointments. The likely cause of failure of overdenture abutments is secondary caries or periodontal disease. A regimen of oral hygiene instruction, dietary control and regular maintenance visits should be prescribed. These three cases have been successful for a minimum of one year. Although this is not a long time, the

patients have become accustomed to wearing removable prostheses. There is a chance with these gold female matrices which were used (Figures 4, 11) that one of the four sections may fracture. This component will then require replacement, which can be done at the chairside or in the laboratory. As with all prostheses, the patients need regular review appointments. REFERENCES 1. 2. e 3. Figure 11. Case 3: Post-treatment (a) Frontal appearance. (b) Palatal view (c) Partial fit surface. (d) Close up of female matrix. (e) Facial view 4. 5. 6. 7. 396 Anon. Glossary of Prosthodontic Terms,7th edition. J Prosthet Dent 1999; 81: 45–106 Basker RM, Harrison A, Ralph JP,Watson CJ. Overdentures in General Dental Practice. London: BDJ Books, 1983. Toolson LB, Taylor TD. A 10 year report of a longitudinal recall of overdenture patients. J Prosthet Dent 1989; 62: 179–181. Crum RJ, Rooney GE. Alveolar bone loss in overdentures: a five year study. J Prosthet Dent 1978; 40: 610–613.

Preiskel HW. Precision attachments in prosthodontics: Overdentures and telescopic prostheses 2. Chicago: Quintessence, 1985 Mensor MC. Removable partial overdentures with mechanical (precision) attachments. Dent Clin North Am 1990; 34(4): 669–681. Fiske J, Davis DM, Frances C, Gelbier S. The emotional effects of tooth loss in edentulous people. Br Dent J 1998; 184: 90–93 Dental Update – September 2003