journal of prosthodontic research 58 (2014) 132–136
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/jpor
Case Report
Replacement of a mandibular implant-fixed prosthesis with an implant-supported overdenture to improve maintenance and care Ken-ichi Matsuda DDS, PhD*, Yuko Kurushima DDS, Kaori Enoki DDS, Kazunori Ikebe DDS, PhD, Yoshinobu Maeda DDS, PhD Osaka University Graduate School of Dentistry, Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Japan
article info
abstract
Article history:
Patients: A 69-year-old woman presented to the Osaka University Dental Hospital. She had
Received 11 April 2013
two chief complaints, (a) food accumulation under the lower teeth and (b) poor maxillary
Received in revised form
denture retention while eating. On clinical examination the patient presented with a
8 December 2013
maxillary complete denture and fixed mandibular implant prosthesis. For preventing food
Accepted 23 December 2013
accumulation under the fixed implant prosthesis and to keep the maxillary denture stable
Available online 6 March 2014
by providing posterior occlusal contact for bilaterally balanced occlusion, the use of a
Keywords:
provided a prosthetic solution for this patient. After provided the new dentures, the patient
BPS
was pleased and was comfortable with the aesthetic, stability and retention of the dentures.
mandibular implant-supported overdenture with self-adjusting magnetic attachments
Implant overdenture
There were no discernable clinical or radiographic changes after 1 year of use.
Complete denture
Discussion: To prevent food accumulation beneath the fixed implant prosthesis and maintain the stability of the maxillary denture by providing posterior occlusal contact for bilaterally balanced occlusion, a mandibular implant-retained overdenture with magnetic attachments was used to provide a prosthetic solution for this patient. Conclusion: In this clinical case, an implant-fixed prosthesis in the edentulous mandibular region was replaced into an implant-supported overdenture with considerations for (a) preventing the food accumulation beneath the lower prosthesis, (b) achieving the proper occlusion in the posterior part for maxillary denture stability and (c) ease of maintenance and care for the prostheses. # 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.
1.
Introduction
Implant dentistry has developed rapidly in recent years and the use of implant-supported dental prostheses that give a high and predictable success rate in rehabilitating the
edentulous mandible is well reported in the literature [1,2]. Though fixed implant prostheses have great advantages for edentulous patients, removable implant-supported overdentures have gained in popularity, offering an especially attractive treatment option due to their relative simplicity, minimal invasiveness, and affordability [3–8]. Indeed, the
* Corresponding author at: Osaka University Graduate School of Dentistry, 1-8 Yamadaoka Suita, Osaka 565-0871, Japan. Tel.: +81 0798 51 1239; fax: +81 6 6879 2957. E-mail address: [email protected] (K.-i. Matsuda). 1883-1958/$ – see front matter # 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved. http://dx.doi.org/10.1016/j.jpor.2013.12.004
journal of prosthodontic research 58 (2014) 132–136
133
Fig. 1 – First examination. Images show the mandibular ridge and the implants supporting the fixed prosthesis (A); the edentulous maxillary ridge (B); and a superior view of the mandible with implant-fixed bridge in place (C).
McGill Consensus Statement indicates that, as a minimal treatment objective, a mandibular two-implant overdenture should be considered as a first-choice standard of care for the edentulous patient [9]. Presently, this Consensus Statement may not be universally accepted. However, this is one of the many opinions, favouring the use of implant-supported overdentures. The advantages of these implant overdentures are their low cost and minimal invasiveness during placement. However, they have another less recognized but important strength, namely ‘ease of self-maintenance’. This is particularly important in the rapidly increasing elderly population that often requires extensive nursing care. Many older patients in nursing homes have poor oral health because of difficulty in accessing professional dental care and problems with dexterity that limit their ability to manage their own personal oral hygiene [10]. Prostheses should be easily cleaned, but many very complex fixed prostheses are hard to maintain with such limited dexterity, so treatment planning must take into account the patient’s ability to look after them. Removable prostheses are much easier to clean, precisely because of their removability. We can maximize the oral health and quality of life of such patients by providing a removable alternative to fixed implant prostheses. This clinical report describes the replacement of an implant-fixed prosthesis with an implant-supported overdenture and the fabrication of a new maxillary complete denture. For the fabrication of both prostheses, the biofunctional prosthetic system (BPS1; Ivoclar Vivadent Inc.; Schaan, Liechtenstein) was used. BPS1 is a complete system for the fabrication of dentures, designed to provide patients with optimal form, function, and aesthetics [11]. This system comprises comprehensive techniques for impression-making, maxillomandibular
relationship recording, tooth placement, fabrication and processing. Furthermore, the system provides high-quality denture base material and artificial teeth, which demonstrate a high strength and a high resistance to wear.
2.
Outline of the case
A 69-year-old woman presented to the Osaka University Dental Hospital with two chief complaints: (a) food accumulation beneath the lower teeth and (b) poor maxillary denture retention while eating. On clinical examination, the patient was found to possess a maxillary complete denture and an implant-fixed prosthesis in the mandible (Fig. 1). There were no significant features in the medical history although, as is common in older individuals, it was suspected that the patient had reduced manual dexterity. The dental history revealed that the patient had lost her teeth 15 years previously due to caries and periodontal disease. The mandibular implant prosthodontic treatment was performed 10 years earlier. Six implants were inserted in the anterior region supporting a cantilevered fixed bridge (Fig. 2). Subsequent resorption of marginal bone and atrophy of the gingival mucosa beneath the bridge resulted in a wide space between the oral mucosa and the superstructure (Fig. 1), which was the primary cause of food accumulation. Furthermore, dental plaque and calculus around the exposed fixture threads were detected. However, there were no signs of peri-implantitis, such as severe mucosal redness or deep peri-implant pockets. The second chief complaint, of poor retention of the maxillary denture, occurred during mastication. Although the fit of this denture was apparently acceptable at rest, it was found that the lower prosthesis occluded disproportionately
134
journal of prosthodontic research 58 (2014) 132–136
Fig. 2 – Panoramic radiograph at the first examination.
Fig. 4 – Completed final impression and maxillomandibular relationship record.
Fig. 3 – Maxillomandibular relationship record using the Centric-tray. Fig. 5 – The new BPS dentures. with the anterior part of the maxillary denture during function, and that this prosthesis rotated and displaced easily. Resolution of these issues required that the space beneath the superstructure be reduced and the posterior occlusal contact re-established. It was planned to replace the implantfixed prosthesis with an implant-supported overdenture and to fabricate a new maxillary complete denture using a BPS. Before the fabrication of the denture was started, the patient received instructions regarding dental hygiene care, and the plaque and calculus were removed by means of scaling and root planning. Preliminary impressions in BPS1 were performed using the Accu-Dent System-1 (Ivoclar Vivadent Inc.), a combination impression system that uses two materials of different viscosity. At the same appointment, a tentative maxillomandibular relationship was recorded using the Centric-Tray system (Ivoclar Vivadent Inc.) (Fig. 3). In the laboratory, individual trays were fabricated for use with the Gnathometer M tracing device (Ivoclar Vivadent Inc.). At the second appointment, this device facilitates the clinical procedures of making final impressions, face-bow transfer, Gothic Arch tracing and maxillomandibular relationship record (Fig. 4). After a wax try-in, the final dentures (Artificial teeth: SR Phonares NHC, Denture base material: Ivocap high-impact; Ivoclar Vivadent Inc.) were inserted (Fig. 5). The implant abutments were selected as follows: Mandibular right and left central incisors and left premolar: cover screw (Bra˚nemark System RP; Nobel Biocare co.; Zurich,
Switzerland); Mandibular right and left canine: Magfit IP-B keeper (Aich Steel Corp.; Aichi, Japan); and mandibular right premolar: healing abutment (Bra˚nemark System RP 4 mm 3 mm; Nobel Biocare co.). Abutments were placed intraorally on each implant and tightened with a torque wrench to appropriate torque following the manufacturer’s instructions (Fig. 6). The mandibular denture base was relieved to accommodate the abutments. A bilaterally balanced occlusal scheme was verified clinically, ensuring equal distribution of posterior occlusal contacts. The upper and lower denture were inserted, and adjusted until the patient felt no pain or discomfort. The patient wore the dentures for 3 weeks prior to magnet attachment placement. The self-adjusting magnetic attachments (Magfit SX; Aich Steel Corp.) were placed on the keeper abutments and incorporated directly into the denture base with self-curing acrylic resin (UNIFAST III; GC Co.; Tokyo, Japan) in a closed mouth procedure [12,13]. The patient was also instructed in brushing techniques. Removable prostheses should be taken out and brushed thoroughly. The surfaces of implant abutments should also be brushed carefully. The patient was highly satisfied with the new dentures, and was comfortable with their aesthetics, stability and retention after two years of use. Dental plaque and calculus around the exposed fixture were not detected, and there was no mucosal
journal of prosthodontic research 58 (2014) 132–136
Fig. 6 – Implant abutments. Mandibular right and left central incisors and left canine were cover screws; right and left lateral incisors were Magfit IP-B keepers; and right canine was a healing abutment.
Fig. 7 – Panoramic radiograph (A) and photograph of gingival conditions around implants (B) at the recall visit (2 years after insertion).
redness or swelling around implant abutments, which maintained a healthy condition during observation period. There were no discernible clinical or radiographic changes around the dental implants (Fig. 7).
3.
Discussion
Before the treatment, a wide space between the oral mucosa and the superstructure was the primary cause of food accumulation. To prevent such an accumulation of food beneath the implant prosthesis in future and to maintain the
135
stability of the maxillary denture, a mandibular implantsupported overdenture with magnetic attachments was used as a prosthetic solution for this patient. The new mandibular prosthesis covered implant abutments and decreased the space so that food accumulation was no longer possible. Since the completion of the treatment, the patient has not complained about any new incident of food accumulation. Before the treatment, the lower prosthesis occluded disproportionately with the anterior part of the maxillary denture during functional activities. Additionally, the maxillary denture rotated and displaced easily. The new maxillary and mandibular prostheses provided posterior bilaterally balanced occlusion. After the treatment, the maxillary denture demonstrated good retention and stability. Implant abutments were selected in the consideration of implant’s positions. At the right and left central incisors and the left premolar position, cover screws were attached in order to ease the cleaning process and allow space for additional strengthening of the metal frame. The sharp figure of the bone was observed at a distal part of the right-premolar implant. We considered it would be likely to cause pain with each denture movement. Therefore, in order to prevent the pressure concentration on that edge, a healing abutment was attached to align the level of the bone and the implant. Misch stated that positioning the implants between the canine and lateral incisor regions is a much better prosthetic option for overdentures in the premolar region. When using the implant in the canine or lateral incisor region, the anterior movement of the prosthesis is reduced compared with an implant at the premolar position [14]. Therefore, magnetic attachments were used in both canine positions in this case. The retention of magnetic attachments is considered to be weaker than that of other designs such as ball, locator and bar attachments. However, in this case, the patient’s manual dexterity was decreased and magnetic attachments considered superior in terms of ease of removal and insertion. Furthermore, the maxillary and mandibular prostheses were complete dentures and a bilaterally balanced occlusion was achieved. It was considered that the resistance to the horizontal displacement was not a significant point to be emphasized and it was more important to decrease the lateral stress on the implants. Self-adjusting magnetic attachments were therefore selected. ‘‘Ease of maintenance and care’’ is particularly important in the rapidly increasing elderly population that often requires extensive nursing care. Many older patients in nursing homes have poor oral health as they have difficulties with performing dental care measures [10]. Prostheses should be easily cleaned, which means that treatment planning must also consider the patients’ ability to take care of and maintain their prostheses. In this case, before treatment, the patient felt it difficult to clean her prosthesis in her mouth because of her decreased manual dexterity. After treatment, that difficulty has been improved, because the prosthesis can be cleaned outside the mouth. Fortunately, this patient had no signs of ‘‘combination syndrome’’ [15]. However, if the posterior occlusal contact was lost following tooth attrition in the mandibular implant overdenture, there would be a loss of stability in the opposing denture and the residual ridge in the edentulous maxilla
136
journal of prosthodontic research 58 (2014) 132–136
would likely resorb. It has been suggested that the risk of severe resorption in the anterior maxilla is increased in wearers of mandibular implant-retained overdentures [16]. However, Denissen et al. reported that restoration of the anterior teeth with no contacts in maximum intercuspation and provision of posterior contacts in eccentric occlusion may minimize loading on the edentulous anterior maxillary segment and thereby reduce bone loss [17]. The occlusion is clearly of great importance to the long-term success of this approach and it is intended to monitor closely the progress of this treatment strategy. Therefore, the patient is scheduled for follow-up appointments every 3 months.
4.
Conclusions
In this clinical case, an implant-fixed prosthesis in the edentulous mandibular region was replaced with an implant-supported overdenture with considerations for (a) preventing the food accumulation beneath the lower prosthesis, (b) achieving the proper occlusion in the posterior part for maxillary denture stability and (c) ease of maintenance and care for the prostheses.
references
[1] Ekelund JA, Lindquist LW, Carlsson GE, Jemt T. Implant treatment in the edentulous mandible: a prospective study on Bra˚nemark system implants over more than 20 years. Int J Prosthodont 2003;16:602–8. [2] Bozini T, Petridis H, Garefis K, Garefis P. A meta-analysis of prosthodontic complication rates of implant-supported fixed dental prostheses in edentulous patients after an observation period of at least 5 years. Int J Oral Maxillofac Implants 2011;26:304–18. [3] Parel SM. Implants and overdentures: the osseointegrated approach with conventional and compromised applications. Int J Oral Maxillofac Implants 1986;1:93–9. [4] Engquist B, Bergendal T, Kallus T, Linden U. A retrospective multicenter evaluation of osseointegrated implants supporting overdentures. Int J Oral Maxillofac Implants 1988;3:129–34.
[5] Naert I, Quirynen M, Theuniers G, van Steenberghe D. Prosthetic aspects of osseointegrated fixtures supporting overdentures. A 4-year report. J Prosthet Dent 1991;65: 671–80. [6] Mericske-Stern R. Clinical evaluation of overdenture restorations supported by osseointegrated titanium implants: a retrospective study. Int J Oral Maxillofac Implants 1990;5:375–83. [7] Zarb GA, Schmitt A. The longitudinal clinical effectiveness of osseointegrated dental implants: the Toronto study. Part II: The prosthetic results. J Prosthet Dent 1990;64: 53–61. [8] Johns RB, Jemt T, Heath MR, Hutton JE, McKenna S, McNamara DC, et al. A multicenter study of overdentures supported by Branemark implants. Int J Oral Maxillofac Implants 1992;7:513–22. [9] Feine JS, Carlsson GE, Awad MA, Chehade A, Duncan WJ, Gizani S, et al. The McGill consensus statement on overdentures. Mandibular two-implant overdentures as first choice standard of care for edentulous patients. Gerodontology 2002;19:3–4. [10] Scannapieco FA, Papandonatos GD, Dunford RG. Association between oral conditions and respiratory disease in a national sample survey population. Ann Periodontol 1998;3:251–6. [11] Nekora-Azak A, Evlioglu G, Ozdemir-Karatas¸ M, Keskin H. Use of biofunctional prosthetic system following partial maxillary resection: a clinical report. J Oral Rehabil 2005;32:693–5. [12] Maeda Y, Yang TC, Kinoshita Y. Development of a selfadjusting magnetic attachment for implant overdentures. Int J Prosthodont 2011;24:241–3. [13] Sadowsky SJ. Mandibular implant-retained overdentures: a literature review. J Prosthet Dent 2001;86:468–73. [14] Misch CE. The edentulous mandible: an organized approach to implant-supported overdentures. In: Misch CE, editor. Contemporary implant dentistry. 3rd ed. Canada: Mosby Inc., an affiliate of Elsevier Inc.; 2008. p. 301–2. [15] Kelly E. Changes caused by a mandibular removable partial denture opposing a maxillary complete denture. J Prosthet Dent 1972;27:140–50. [16] Lechner SK, Mammen A. Combination syndrome in relation to osseointegrated implant-supported overdentures: a survey. Int J Prosthodont 1996;9:58–64. [17] Denissen HW, Kalk W, van Waas MA, van Os JH. Occlusion for maxillary dentures opposing osseointegrated mandibular prostheses. Int J Prosthodont 1993;6:446–50.
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.elsevier.com/locate/jpor
Case Report
Replacement of a mandibular implant-fixed prosthesis with an implant-supported overdenture to improve maintenance and care Ken-ichi Matsuda DDS, PhD*, Yuko Kurushima DDS, Kaori Enoki DDS, Kazunori Ikebe DDS, PhD, Yoshinobu Maeda DDS, PhD Osaka University Graduate School of Dentistry, Department of Prosthodontics, Gerodontology and Oral Rehabilitation, Japan
article info
abstract
Article history:
Patients: A 69-year-old woman presented to the Osaka University Dental Hospital. She had
Received 11 April 2013
two chief complaints, (a) food accumulation under the lower teeth and (b) poor maxillary
Received in revised form
denture retention while eating. On clinical examination the patient presented with a
8 December 2013
maxillary complete denture and fixed mandibular implant prosthesis. For preventing food
Accepted 23 December 2013
accumulation under the fixed implant prosthesis and to keep the maxillary denture stable
Available online 6 March 2014
by providing posterior occlusal contact for bilaterally balanced occlusion, the use of a
Keywords:
provided a prosthetic solution for this patient. After provided the new dentures, the patient
BPS
was pleased and was comfortable with the aesthetic, stability and retention of the dentures.
mandibular implant-supported overdenture with self-adjusting magnetic attachments
Implant overdenture
There were no discernable clinical or radiographic changes after 1 year of use.
Complete denture
Discussion: To prevent food accumulation beneath the fixed implant prosthesis and maintain the stability of the maxillary denture by providing posterior occlusal contact for bilaterally balanced occlusion, a mandibular implant-retained overdenture with magnetic attachments was used to provide a prosthetic solution for this patient. Conclusion: In this clinical case, an implant-fixed prosthesis in the edentulous mandibular region was replaced into an implant-supported overdenture with considerations for (a) preventing the food accumulation beneath the lower prosthesis, (b) achieving the proper occlusion in the posterior part for maxillary denture stability and (c) ease of maintenance and care for the prostheses. # 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved.
1.
Introduction
Implant dentistry has developed rapidly in recent years and the use of implant-supported dental prostheses that give a high and predictable success rate in rehabilitating the
edentulous mandible is well reported in the literature [1,2]. Though fixed implant prostheses have great advantages for edentulous patients, removable implant-supported overdentures have gained in popularity, offering an especially attractive treatment option due to their relative simplicity, minimal invasiveness, and affordability [3–8]. Indeed, the
* Corresponding author at: Osaka University Graduate School of Dentistry, 1-8 Yamadaoka Suita, Osaka 565-0871, Japan. Tel.: +81 0798 51 1239; fax: +81 6 6879 2957. E-mail address: [email protected] (K.-i. Matsuda). 1883-1958/$ – see front matter # 2014 Japan Prosthodontic Society. Published by Elsevier Ireland. All rights reserved. http://dx.doi.org/10.1016/j.jpor.2013.12.004
journal of prosthodontic research 58 (2014) 132–136
133
Fig. 1 – First examination. Images show the mandibular ridge and the implants supporting the fixed prosthesis (A); the edentulous maxillary ridge (B); and a superior view of the mandible with implant-fixed bridge in place (C).
McGill Consensus Statement indicates that, as a minimal treatment objective, a mandibular two-implant overdenture should be considered as a first-choice standard of care for the edentulous patient [9]. Presently, this Consensus Statement may not be universally accepted. However, this is one of the many opinions, favouring the use of implant-supported overdentures. The advantages of these implant overdentures are their low cost and minimal invasiveness during placement. However, they have another less recognized but important strength, namely ‘ease of self-maintenance’. This is particularly important in the rapidly increasing elderly population that often requires extensive nursing care. Many older patients in nursing homes have poor oral health because of difficulty in accessing professional dental care and problems with dexterity that limit their ability to manage their own personal oral hygiene [10]. Prostheses should be easily cleaned, but many very complex fixed prostheses are hard to maintain with such limited dexterity, so treatment planning must take into account the patient’s ability to look after them. Removable prostheses are much easier to clean, precisely because of their removability. We can maximize the oral health and quality of life of such patients by providing a removable alternative to fixed implant prostheses. This clinical report describes the replacement of an implant-fixed prosthesis with an implant-supported overdenture and the fabrication of a new maxillary complete denture. For the fabrication of both prostheses, the biofunctional prosthetic system (BPS1; Ivoclar Vivadent Inc.; Schaan, Liechtenstein) was used. BPS1 is a complete system for the fabrication of dentures, designed to provide patients with optimal form, function, and aesthetics [11]. This system comprises comprehensive techniques for impression-making, maxillomandibular
relationship recording, tooth placement, fabrication and processing. Furthermore, the system provides high-quality denture base material and artificial teeth, which demonstrate a high strength and a high resistance to wear.
2.
Outline of the case
A 69-year-old woman presented to the Osaka University Dental Hospital with two chief complaints: (a) food accumulation beneath the lower teeth and (b) poor maxillary denture retention while eating. On clinical examination, the patient was found to possess a maxillary complete denture and an implant-fixed prosthesis in the mandible (Fig. 1). There were no significant features in the medical history although, as is common in older individuals, it was suspected that the patient had reduced manual dexterity. The dental history revealed that the patient had lost her teeth 15 years previously due to caries and periodontal disease. The mandibular implant prosthodontic treatment was performed 10 years earlier. Six implants were inserted in the anterior region supporting a cantilevered fixed bridge (Fig. 2). Subsequent resorption of marginal bone and atrophy of the gingival mucosa beneath the bridge resulted in a wide space between the oral mucosa and the superstructure (Fig. 1), which was the primary cause of food accumulation. Furthermore, dental plaque and calculus around the exposed fixture threads were detected. However, there were no signs of peri-implantitis, such as severe mucosal redness or deep peri-implant pockets. The second chief complaint, of poor retention of the maxillary denture, occurred during mastication. Although the fit of this denture was apparently acceptable at rest, it was found that the lower prosthesis occluded disproportionately
134
journal of prosthodontic research 58 (2014) 132–136
Fig. 2 – Panoramic radiograph at the first examination.
Fig. 4 – Completed final impression and maxillomandibular relationship record.
Fig. 3 – Maxillomandibular relationship record using the Centric-tray. Fig. 5 – The new BPS dentures. with the anterior part of the maxillary denture during function, and that this prosthesis rotated and displaced easily. Resolution of these issues required that the space beneath the superstructure be reduced and the posterior occlusal contact re-established. It was planned to replace the implantfixed prosthesis with an implant-supported overdenture and to fabricate a new maxillary complete denture using a BPS. Before the fabrication of the denture was started, the patient received instructions regarding dental hygiene care, and the plaque and calculus were removed by means of scaling and root planning. Preliminary impressions in BPS1 were performed using the Accu-Dent System-1 (Ivoclar Vivadent Inc.), a combination impression system that uses two materials of different viscosity. At the same appointment, a tentative maxillomandibular relationship was recorded using the Centric-Tray system (Ivoclar Vivadent Inc.) (Fig. 3). In the laboratory, individual trays were fabricated for use with the Gnathometer M tracing device (Ivoclar Vivadent Inc.). At the second appointment, this device facilitates the clinical procedures of making final impressions, face-bow transfer, Gothic Arch tracing and maxillomandibular relationship record (Fig. 4). After a wax try-in, the final dentures (Artificial teeth: SR Phonares NHC, Denture base material: Ivocap high-impact; Ivoclar Vivadent Inc.) were inserted (Fig. 5). The implant abutments were selected as follows: Mandibular right and left central incisors and left premolar: cover screw (Bra˚nemark System RP; Nobel Biocare co.; Zurich,
Switzerland); Mandibular right and left canine: Magfit IP-B keeper (Aich Steel Corp.; Aichi, Japan); and mandibular right premolar: healing abutment (Bra˚nemark System RP 4 mm 3 mm; Nobel Biocare co.). Abutments were placed intraorally on each implant and tightened with a torque wrench to appropriate torque following the manufacturer’s instructions (Fig. 6). The mandibular denture base was relieved to accommodate the abutments. A bilaterally balanced occlusal scheme was verified clinically, ensuring equal distribution of posterior occlusal contacts. The upper and lower denture were inserted, and adjusted until the patient felt no pain or discomfort. The patient wore the dentures for 3 weeks prior to magnet attachment placement. The self-adjusting magnetic attachments (Magfit SX; Aich Steel Corp.) were placed on the keeper abutments and incorporated directly into the denture base with self-curing acrylic resin (UNIFAST III; GC Co.; Tokyo, Japan) in a closed mouth procedure [12,13]. The patient was also instructed in brushing techniques. Removable prostheses should be taken out and brushed thoroughly. The surfaces of implant abutments should also be brushed carefully. The patient was highly satisfied with the new dentures, and was comfortable with their aesthetics, stability and retention after two years of use. Dental plaque and calculus around the exposed fixture were not detected, and there was no mucosal
journal of prosthodontic research 58 (2014) 132–136
Fig. 6 – Implant abutments. Mandibular right and left central incisors and left canine were cover screws; right and left lateral incisors were Magfit IP-B keepers; and right canine was a healing abutment.
Fig. 7 – Panoramic radiograph (A) and photograph of gingival conditions around implants (B) at the recall visit (2 years after insertion).
redness or swelling around implant abutments, which maintained a healthy condition during observation period. There were no discernible clinical or radiographic changes around the dental implants (Fig. 7).
3.
Discussion
Before the treatment, a wide space between the oral mucosa and the superstructure was the primary cause of food accumulation. To prevent such an accumulation of food beneath the implant prosthesis in future and to maintain the
135
stability of the maxillary denture, a mandibular implantsupported overdenture with magnetic attachments was used as a prosthetic solution for this patient. The new mandibular prosthesis covered implant abutments and decreased the space so that food accumulation was no longer possible. Since the completion of the treatment, the patient has not complained about any new incident of food accumulation. Before the treatment, the lower prosthesis occluded disproportionately with the anterior part of the maxillary denture during functional activities. Additionally, the maxillary denture rotated and displaced easily. The new maxillary and mandibular prostheses provided posterior bilaterally balanced occlusion. After the treatment, the maxillary denture demonstrated good retention and stability. Implant abutments were selected in the consideration of implant’s positions. At the right and left central incisors and the left premolar position, cover screws were attached in order to ease the cleaning process and allow space for additional strengthening of the metal frame. The sharp figure of the bone was observed at a distal part of the right-premolar implant. We considered it would be likely to cause pain with each denture movement. Therefore, in order to prevent the pressure concentration on that edge, a healing abutment was attached to align the level of the bone and the implant. Misch stated that positioning the implants between the canine and lateral incisor regions is a much better prosthetic option for overdentures in the premolar region. When using the implant in the canine or lateral incisor region, the anterior movement of the prosthesis is reduced compared with an implant at the premolar position [14]. Therefore, magnetic attachments were used in both canine positions in this case. The retention of magnetic attachments is considered to be weaker than that of other designs such as ball, locator and bar attachments. However, in this case, the patient’s manual dexterity was decreased and magnetic attachments considered superior in terms of ease of removal and insertion. Furthermore, the maxillary and mandibular prostheses were complete dentures and a bilaterally balanced occlusion was achieved. It was considered that the resistance to the horizontal displacement was not a significant point to be emphasized and it was more important to decrease the lateral stress on the implants. Self-adjusting magnetic attachments were therefore selected. ‘‘Ease of maintenance and care’’ is particularly important in the rapidly increasing elderly population that often requires extensive nursing care. Many older patients in nursing homes have poor oral health as they have difficulties with performing dental care measures [10]. Prostheses should be easily cleaned, which means that treatment planning must also consider the patients’ ability to take care of and maintain their prostheses. In this case, before treatment, the patient felt it difficult to clean her prosthesis in her mouth because of her decreased manual dexterity. After treatment, that difficulty has been improved, because the prosthesis can be cleaned outside the mouth. Fortunately, this patient had no signs of ‘‘combination syndrome’’ [15]. However, if the posterior occlusal contact was lost following tooth attrition in the mandibular implant overdenture, there would be a loss of stability in the opposing denture and the residual ridge in the edentulous maxilla
136
journal of prosthodontic research 58 (2014) 132–136
would likely resorb. It has been suggested that the risk of severe resorption in the anterior maxilla is increased in wearers of mandibular implant-retained overdentures [16]. However, Denissen et al. reported that restoration of the anterior teeth with no contacts in maximum intercuspation and provision of posterior contacts in eccentric occlusion may minimize loading on the edentulous anterior maxillary segment and thereby reduce bone loss [17]. The occlusion is clearly of great importance to the long-term success of this approach and it is intended to monitor closely the progress of this treatment strategy. Therefore, the patient is scheduled for follow-up appointments every 3 months.
4.
Conclusions
In this clinical case, an implant-fixed prosthesis in the edentulous mandibular region was replaced with an implant-supported overdenture with considerations for (a) preventing the food accumulation beneath the lower prosthesis, (b) achieving the proper occlusion in the posterior part for maxillary denture stability and (c) ease of maintenance and care for the prostheses.
references
[1] Ekelund JA, Lindquist LW, Carlsson GE, Jemt T. Implant treatment in the edentulous mandible: a prospective study on Bra˚nemark system implants over more than 20 years. Int J Prosthodont 2003;16:602–8. [2] Bozini T, Petridis H, Garefis K, Garefis P. A meta-analysis of prosthodontic complication rates of implant-supported fixed dental prostheses in edentulous patients after an observation period of at least 5 years. Int J Oral Maxillofac Implants 2011;26:304–18. [3] Parel SM. Implants and overdentures: the osseointegrated approach with conventional and compromised applications. Int J Oral Maxillofac Implants 1986;1:93–9. [4] Engquist B, Bergendal T, Kallus T, Linden U. A retrospective multicenter evaluation of osseointegrated implants supporting overdentures. Int J Oral Maxillofac Implants 1988;3:129–34.
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