Читать книгу Fundamentals of Implant Dentistry - John III Beumer - Страница 17
ОглавлениеEdentulous Patients: Patterns of Bone Resorption and Clinical Outcomes with Implants
Neal Garrett | Ichiro Nishimura | Sunyoung Ma | Karl M. Lyons
Many patients are able to function effectively and comfortably with conventional complete dentures, with percentages of patients reporting moderate to high levels of denture satisfaction frequently over 80%.1–4 However, some patients have difficulty adapting to or accepting conventional dentures (CDs) for a variety of reasons. For certain patients, the existing denture-bearing surfaces do not provide sufficient retention, stability, and support to ensure effective function of the mandible denture. This difficulty with unstable and poorly retained and supported mandibular CDs was a critical factor in the development of dental implants. Even in patients with reasonable denture-bearing surfaces, common mandibular denture movement during oral function may compromise the patient’s ability to simultaneously control the mandibular denture and the food bolus, leading to additional impairment in mastication and comfort. Therefore, several essential questions arise regarding implant-retained mandibular overdentures:
• Which patients stand to benefit the most from implant therapy, and how do you identify them?
• Will mandibular implant-retained or -supported prostheses improve the masticatory function of all edentulous patients or just some of them?
• What are the success rates for various implant-based restorations for the edentulous maxilla and mandible?
• Does the nature of implant retention or support (eg, number of implants, types of attachment) impact oral function and patient satisfaction?
• Will the placement of osseointegrated implants prevent the natural processes of ridge resorption associated with denture use?
• Has this service become the validated treatment?
Resorption Patterns
Long-term denture use contributes to resorption of the edentulous mandible.5–7 Denture use during sleeping hours is especially destructive, particularly if the patient presents with chronic bruxing and grinding habits. Furthermore, in the case of Kelly’s combination syndrome,8 the mucoperiosteum of maxillary anterior and mandibular posterior regions is compressed by occlusal forces and precipitates a resorptive remodeling response of the underlying bone.
The molecular mechanisms of compression force–derived residual ridge resorption have yet to be fully elucidated. Yeh and Rodan9 reported that the application of tensile forces to cells results in the secretion of stress-induced molecules such as prostaglandin E (PGE), a well-known inducer of bone resorption. Stress–induced PGE may also be involved in orthodontic tooth movement, where compression of periodontal ligament cells leads to production of PGE as well as other bone resorption–inducing molecules, resulting in resorption of alveolar bone.10 In an experimental model using edentulous rats, mandibular residual ridge resorption was shown to be regulated in part by PGE. The application of a cyclo- oxygenase inhibitor, blocking prostaglandin synthesis, effectively reduced bone resorption by up to 50%.11 Denture- induced residual ridge resorption hence may be explained by the mechanical stress-induced production of bone resorption mediators by the mucoperiosteum.
Following tooth extraction, bone resorption continues but at a reduced rate (Fig 6-1). After Tallgren12 and Atwood13 reported this phenomenon, Carlsson and Persson14 documented its progression (Fig 6-2) and showed that loss of mandibular bone height was most rapid during the first 6 to 8 months after tooth extraction, which was followed by continuous resorption but at a reduced rate. Carlsson and Persson14 also indicated that the rate of residual ridge resorption varies considerably among patients.
Fig 6-1 Continuous ridge resorption following tooth extraction. (a) Initial situation. (b) After 1 month. (c) After 3 months. (d) After 7 months. (e) After 17 years. (f) After 25 years.
Fig 6-2 Residual ridge resorption (RRR). Min, minimum; avg, average; max, maximum. (Data from Carlsson and Persson.14)
Since this observation, numerous studies have addressed the possible causes of excessive residual ridge resorption in select patients (for a review, see Jahangiri et al15). These studies primarily addressed: (1) anatomical factors, ie, maxilla versus mandible; (2) prosthodontic factors, ie, monoplane teeth versus anatomical teeth; and (3) systemic factors, ie, osteoporosis. Approximately 30% to 40% of women in the United States develop postmenopausal osteoporosis, and many are edentulous. However, most studies examining the effect of osteoporosis (ie, reduced bone mineral index) and the loss of mandibular residual ridge height have repeatedly failed to find any.7,16–18 However, Nishimura et al19 reported that postmenopausal osteoporotic women appeared to maintain the height of the edentulous mandible but significantly lost its width, leading to the development of a “knife-edge” residual ridge (Fig 6-3). The development of the “knife-edge” morphology was positively correlated with the loss of bone mineral density in cervical vertebral bones. Furthermore, clinical observations of patients with a knife-edge mandibular residual ridge revealed that there was a distinct undercut in the overlying oral mucosa,20 which was not evident in the flat residual ridge (see Fig 6-3). In addition, the edentulous maxilla of some osteoporotic patients exhibits severe bone resorption,21 with the ridge often covered by thin and highly stretched oral mucosa. Therefore, it is conceivable that systemic conditions associated with postmenopausal osteoporosis may affect oral mucoperiosteum remodeling and thus secondarily influence the pattern of residual ridge resorption.
Fig 6-3 Patients with osteoporosis tend to develop a knife-edge ridge with a mucosal undercut in the anterior region. (a) Typical resorption pattern. (b) Resorption pattern of an osteoporotic patient. Note the small maxilla and the knife-edge mandible. (c) Radiograph of a flat residual ridge. (d) Radiograph of a knife-edge residual ridge. (e) Intraoral view of a flat residual ridge. (f) Intraoral view of a knife-edge residual ridge.
Wound closure
Tooth extraction creates a sizable open wound in the oral cavity. While the bony socket is actively filled with newly formed alveolar bone and later remodeled, the gingival flaps undergo rapid contraction toward the center of the extraction socket (Fig 6-4). Longitudinal observations in monkeys reveal that oral mucosa contraction occurred not only during the extraction wound healing but persisted throughout the experimental period of 6 months.22 As a result, the edentulous mucosa tightly adhered to the actively resorbing residual alveolar bone (see Fig 6-4). The tight adherence of overlying oral mucosa to the highly atrophied maxilla and mandible has been described by DeVan.23
Fig 6-4 Rapid contraction of the extraction site after 7 days of healing. (a) Extraction site immediately after extraction. (b) Extraction site 1 week later.
Sukotjo et al24 isolated a novel gene from rat gingiva after tooth extraction wounding and called it wound-inducible transcript 3.0 or wit3.0. The expression of wit3.0 in the oral mucosa was significantly activated by tooth extraction in animals24 as well as in humans,25 and the high level of wit3.0 expression appeared to continue after initial healing of the extraction site. Wit3.0 is a small cytoskeleton molecule also called fibroblast growth factor receptor 1 oncogene partner 2 (FGFR1OP2) that contributes to the fibroblast-derived tissue contraction in vitro26 and in vivo.27 The wound- induced overexpression of FGFR1OP2/wit3.0 appeared to be a unique phenomenon for oral mucosa. For example, full-thickness open wounds created in mouse skin do not significantly induce its expression. Therefore, it has been postulated that the wound-induced synthesis of FGFR1OP2/wit3.0 is unique to the oral mucosa and facilitates the rapid wound closure after tooth extraction.
Various methods have been used to prevent this initial contraction and the subsequent resorption, including immediate implant placement and socket preservation.28 However, human studies assessing the effect of preservation of the alveolar bone are limited. Animal studies using nonresorbable bone substitutes or autologous bone particulates appeared to induce bone formation within the socket space29,30; however, these procedures do not seem to completely prevent bone resorption activity on the external surfaces of the extraction socket, resulting in the development of a knife-edge residual ridge. New biomaterials and techniques to minimize contraction of the oral mucosa and resorption of alveolar bone can provide more predictable management of the soft and hard tissues around dental implants.
Bone density
In a classic study by von Wowern and Gotfredsen,31 the placement of two implants in the canine region prevented the long-term (5 years) reduction of bone mineral content (bone density) adjacent to the implant site. It has been postulated that implants retaining the mandibular overdenture will prevent compression of the mucoperiosteum anteriorly; if the denture properly engages the primary support areas posteriorly (buccal shelf and retromolar pad), there should be little resorption of the intervening alveolar ridge and mandibular body. The benefit should be considerable when the opposing maxilla is fully or partially dentate.
Interestingly, there have been numerous reports of the size and density of the mandibular body increasing following the placement of implants in the mandibular symphysis and the fabrication of a fixed implant-supported prosthesis32 (Fig 6-5). While this phenomenon appears to be most common in patients with severe resorption, the causes of have yet to be determined. Davis et al32 speculated that with the occlusal forces concentrated anteriorly and when those forces increased dramatically during function, significant bending moments are created in the body of the mandible that produce tensional forces on the superior surface, provoking osteoblastic activity and deposition of bone. The role of biomechanics on bone remodeling is detailed in chapter 3.
Fig 6-5 (a and b) Implants placed into a moderately resorbed mandible. (c) A fixed hybrid prosthesis was fabricated. Note the additional bone formed over the inferior alveolar nerve 10 years after delivery. (Courtesy of Dr H. Davis.)
Genetic factors
Implant placement after dental extraction for the purpose of maintaining the alveolar bone has been a well-accepted practice. However, implants do not prevent bone loss in all cases, and it is possible that the oral mucosa may play a role under certain combinations of risk factors. It is increasingly clear that many diseases and afflictions are caused by the interactions among genetic and environmental factors. If the placement of implants and denture-induced compression of the mucoperiosteum of the alveolar ridge are considered environmental factors, the individual variations in response to similar treatment may be related to the patient’s genetic factors. Using FGFR1OP2/wit3.0 as a genetic paradigm, Suwanwela et al25 demonstrated a method that may be used to identify those patients at risk for rapid bone resorption upon becoming edentulous. Two out of six single-nucleotide polymorphisms (SNPs) within the FGFR1OP2/wit3.0 genetic allele were strongly associated with severe mandibular atrophy25 (Fig 6-6). Current dental practice employs minimal clinical testing and bases the diagnosis and the prognosis of each patient almost entirely on empiric experiences. In the future, it may be possible that genetic screening tests using oral rinse or cheek swab samples will be available to assist with this problem.
Fig 6-6 Twenty long-term edentulous patients were recruited for a genetic association study. The mandibular residual ridge height was measured following the protocol of the American College of Prosthodontists. Two SNPs in the FGFR1OP2/wit3.0 gene were positively associated with atrophic mandibular residual ridges. This pilot study may suggest a possible genetic screening test for better prognosis of severe residual ridge resorption even prior to tooth extraction. (a) Panoramic radiographs illustrating ridge resorption. (b) SNP alleles in FGFR1OP2/wit3.0. (c) Ridge heights for SNP alleles. (Reprinted from Suwanwela et al25 with permission.)
The authors believe that the placement of two implants into the anterior mandible to retain an overdenture will minimize further resorption of the alveolar ridge and the body of the mandible. A properly engaged retromolar pad and buccal shelf provide posterior support while the implants provide anterior support. In addition, the implants minimize lateral and posterior displacement and movement of the denture during function and parafunction. In addition to the environmental control by clinical procedures, genetic diagnosis may become available in the future.
Clinical Outcomes: Mastication, Satisfaction, and Diet
Masticatory function
Concern with restoration of function following tooth loss as well as frequent complaints by denture wearers regarding chewing difficulties have resulted in considerable research on masticatory function with compromised dentition. In the case of the edentulous patient, early studies of dentate patients and complete denture wearers demonstrated that significant impairment in masticatory function remains following treatment with complete dentures. Masticatory performance (degree of particle breakdown) with complete dentures is typically less than half of that achieved by persons with relatively intact dentition (28 or more teeth). It was hypothesized that with the improved stability and retention gained when the mandibular denture is retained or supported by dental implants, significant improvements in masticatory function would be achieved. A number of well-controlled clinical trials have been conducted evaluating the restoration of masticatory function with implant-retained mandibular dentures compared with conventional complete dentures.
Geertman et al33 evaluated masticatory performance in patients receiving a two-implant bar-retained overdenture (IOD) or CD in the mandible opposing a new maxillary CD. The group treated with the IOD in the mandible had significantly greater masticatory performance than the CD group. A key element in this study was the sample characteristic that all subjects had severely resorbed mandibles. In another randomized controlled trial (RCT) comparing treatment with a mandibular IOD (Fig 6-7) or CD opposing new maxillary CDs, Garrett et al34 reported no significant difference in masticatory performance between the two treatment groups. However, the subjects for this study were not selected because of dissatisfaction with their CDs or severe resorption of the mandibular residual ridge, and the overall residual ridge height for the sample was generally good. When subjects in this study were stratified for residual ridge height, those subjects with more resorbed mandibular ridges were found to have significantly greater masticatory performance with the IOD compared with the CD.35
Fig 6-7 (a) An implant-assisted Hader bar fabricated with UCLA-type abutments has been screwed onto the implants. (b) Overdenture with Hader clips.
The impact of mandibular ridge height on masticatory function following mandibular IOD treatment was further reinforced by Fontijn-Tekamp et al.36 Masticatory function in subjects with resorbed mandibles was significantly greater with the IOD compared with the CD. However, the masticatory performance of the IOD group with a resorbed mandible was still lower than the performance of a group of subjects with good mandibular residual ridges treated with CDs. It is clear that the benefits in masticatory function of IOD treatment are evident only in patients with relatively resorbed mandibular ridges and that the improvement in masticatory function is only to the level of a CD wearer with a good mandibular residual ridge.
Increasing the number of implants in the mandible to four to six to support an overdenture (Fig 6-8a) has been found to offer little advantage in masticatory function. Geertman et al33 found that the additional support provided by transmandibular implants and a fully implant-supported denture did not improve masticatory performance compared with the two-implant overdenture. The authors concluded that the increased retention and stability of the mandibular denture determined the denture wearer’s ability to grind up food during mastication, rather than the degree of support provided by implants. Tang et al37 reported a similar lack of difference in masticatory function based on within-subject comparisons of a mandibular long-bar (four implants) overdenture and a two-implant overdenture.
Fig 6-8 (a) Implant-supported bar design. (b) The original fixed hybrid prosthesis design sitting atop conventional titanium abutments.
Feine et al38 extended the comparison of masticatory function with removable implant-supported long-bar overdentures to fixed prostheses (Fig 6-8b) in a within-subject crossover study. The fixed prosthesis offered no improvement over the implant-supported overdenture. In fact, the long-bar overdenture resulted in significantly better masticatory times for three of the five foods evaluated.
Lindquist and Carlsson,39,40 on the other hand, found that patients who were not satisfied with acceptable CDs and those treated with mandibular implant-supported fixed prostheses experienced significant improvement in masticatory function. However, the addition of an implant-supported fixed prosthesis in the maxilla did not result in any improvement in masticatory performance over the mandibular fixed prosthesis opposing a maxillary CD.
Patient satisfaction
Patient perceptions of denture function
In general, patients report high levels of satisfaction with almost all prosthodontic interventions, including rehabilitation with dental implants. For example, improvements to the denture base fit, occlusion, and occlusal vertical dimension of clinically poor dentures, as well as delivery of new CDs, generate high percentages of patients reporting improved function and security with each change in the denture41 (Fig 6-9). Relatively high satisfaction with CDs is often seen in general samples of denture wearers, such as the 82% reporting good global satisfaction with their dentures in the study by Gjengedal et al.4 However, changes in patient perceptions from baseline with CDs to treatment with prostheses retained or supported by dental implants have been used to recommend implant-based therapies.
Fig 6-9 Percentage of patients reporting improvement in denture satisfaction regarding changes in occlusion (green), vertical dimension (yellow), and use of denture adhesive (blue) as well as after relining (red) and 3 weeks (gray) and 3 months (brown) after the delivery of new dentures. (Based on data from Garrett et al.42)
For patients generally dissatisfied with CDs (ie, more than 90% of the sample) and with severely resorbed mandibles, two-implant mandibular overdentures produce significant improvement in patient satisfaction compared with CDs.43,44 In patients with relatively good residual ridges and little dissatisfaction with their existing CDs, comparisons of CD patients randomized to treatment with another CD or a two-implant overdenture in the mandible opposing a new maxillary CD found that a significantly higher percentage of patients with the IOD noted improvements in chewing ability after 6 months (Fig 6-10), while there was little difference between the two groups at 24 months posttreatment.45 The lack of difference at 24 months may indicate that some patients took longer to adapt to their new CDs compared with the IOD wearers. More than 84% of the patients were moderately or fully satisfied and experienced little or no discomfort with new CDs, and no significant differences were seen in denture satisfaction with the new IOD. Although not statistically significant, the patient satisfaction levels regarding chewing ability, chewing comfort, and food selection were somewhat higher with the IOD compared with the CD.
Fig 6-10 Percentage of patients reporting improvement or deterioration 6 months after placement of new CDs or IODs. (Reprinted from Kapur et al45 with permission.)
A similar study compared the effects of new CDs and mandibular implant overdentures on the perceptions of patients who had low satisfaction scores with their original CDs.46,47 Perceptions regarding general satisfaction, comfort, stability, and chewing ability significantly improved following provision of new maxillary CDs with either a mandibular CD or IOD. The ratings on a visual analog scale for these four perceptions were significantly greater with the IOD compared with the CD, but some of this difference can be accounted for by the poorer ratings the CD group gave their original dentures compared with the IOD group. However, while both treatments provided considerable perceived improvement, the impact of IODs on patient ratings of satisfaction, comfort, stability, and chewing was greater than that of the CDs. These benefits of the IOD in treatment satisfaction have been extended to international populations in a study incorporating the many elements of an effectiveness trial, indicating that this benefit is likely to persist at the private practitioner level.48 Unlike as in RCTs, participants in this study selected the type of treatment (ie, CD or IOD) they preferred. As evident in Fig 6-11, while general satisfaction with the new prosthesis improved with both CD and IOD treatment, the magnitude of improvement is greater for those receiving the IOD.
Fig 6-11 Mean in general satisfaction rating on 100-mm visual analog scale of mandibular prostheses with both CD and IOD treatment. (Based on data from Rashid et al.48)
Improvements in treatment satisfaction and oral health quality of life (OHQoL) were seen for patients requesting CD or IOD treatment and receiving their preferred treatment.49,50 Again the improvements were greater for the IOD group. However, patients requesting the IOD but receiving CD treatment showed no change in satisfaction or QoL. Clearly, patient expectations play a significant role in achieving treatment satisfaction.
Edentulous denture wearers with adequate ridges who reported persistent problems wearing CDs were treated with a new maxillary CD along with either a new mandibular CD, preprosthetic surgery (PPS, ie, vestibuloplasty; Fig 6-12) and a new mandibular CD (PPS+CD), or a new IOD in the mandible.51 Increased denture satisfaction was seen with both the IOD and PPS+CD groups compared with the CD group at 1 year posttreatment. At 5 years posttreatment, no differences were seen in denture satisfaction among the three groups; however, the percentage of patients with denture complaints was significantly lower for those with an IOD compared with a CD. After 10 years with the study dentures, no differences in denture satisfaction or denture complaints were seen among the three groups.52 The use of PPS to improve the denture foundation area and denture fit resulted in improvements in denture satisfaction of the same magnitude as the IOD. Although mandibular ridge height has clearly been shown to interact with masticatory function with IODs, it is questionable whether there is any relationship between mandibular residual ridge resorption and patient ratings of denture satisfaction, chewing ability, stability, or comfort with mandibular overdentures.53
Fig 6-12 Patient with a skin graft vestibuloplasty. The floor of the mouth was also lowered. The result is improved support and stability for the CD.
Increased implant support and patient perceptions
This section focuses mostly on the effect of implant bar–retained overdentures on patient experience. Chapter 7 addresses the use of overdentures retained with individual attachments. Reducing or eliminating the amount of soft tissue support to improve stability and reduce limitations in function due to pressure or pain on the soft tissue has been achieved by increasing the number of implants and using implant- supported long-bar overdentures or fixed prostheses (Fig 6-13). With the additional stability and support provided by the fully implant-supported prosthesis in the mandible, the long-bar overdenture was seen to provide significant improvements in perceptions of general satisfaction, denture fit, comfort, esthetics, and chewing compared with a two- implant overdenture.37 In addition, all of the participants in this within-subject study chose to keep the long-bar overdenture, a strong indicator of patient preference. However, Geertman et al43 found that increasing the number of implants in the mandible to four to support an overdenture opposing a maxillary CD did not produce any additional improvement in perceptions of satisfaction with the denture or subjective chewing ability, nor did it reduce the number of complaints. Differences in methodology and the sensitivity of the survey instruments may account for much of the discrepancy between these studies.
Fig 6-13 (a and b) Implant-supported overdenture. All the forces of occlusion are borne by the implants.
Comparisons between different types of fully implant- supported dentures have indicated little difference in patient perceptions and treatment satisfaction. Patients with severely resorbed ridges treated with either four-post transmandibular implants, ridge augmentation with four implants, or four short implants and mandibular overdentures reported significant improvements over their CD in denture satisfaction and psychosocial function.54 All three treatments were equally perceived as being significantly better than the original CD.
Similarly, Feine et al38 found that patients treated with either a long-bar overdenture or a fixed prosthesis in the mandible (Fig 6-14) all reported significant improvement in general satisfaction over their original CDs, but the two types of prostheses were rated equally for almost all the study measures. Key to this study was the opportunity for patients to pick which prosthesis they wanted to keep at the end of the evaluation. The selections were evenly split between the two treatments, with eight subjects choosing the fixed hybrid prosthesis, primarily due to concerns with stability, and seven choosing the removable prosthesis, primarily due to ease of cleaning the tissue bar. Age was also a consideration, with older patients being more likely to choose the removable prosthesis.
Fig 6-14 Implant-supported metal-ceramic fixed dental prosthesis.
Many patients are relatively satisfied with a new CD, particularly if they have adequate residual ridges. Treatment with a mandibular IOD can significantly improve perceptions of denture satisfaction and function for many patients with denture adaptation problems or severely resorbed ridges. Increasing implant support of the mandibular denture may provide additional improvements in patient perceptions of the denture, but the evidence is currently not sufficient to support this observation.
Diet and nutrition
The impairments in masticatory function from increased tooth loss and prosthetic replacement in the elderly, who are also at increased risk of chronic and acute disease, has heightened concern about their ability to meet dietary and nutritional requirements. Particularly in the more fragile elderly who have experienced tooth loss, the hope was that prosthodontic restorations with implants would provide them with greater comfort, stability, and perceived chewing ability compared with a CD and in return lead them to consume a healthier diet. However, dietary selection and nutrition in complete denture wearers does not appear to be dramatically influenced by the provision of IODs compared with CDs.55,56 For example, in an RCT of elderly complete denture wearers with type 2 diabetes, provision of new dentures with either an implant-supported or conventional mandibular denture did not result in alteration of the diet in either group to produce any improvement in nutritional intake.57 The percentage of patients with intake levels more than 25% below the recommended daily allowance for 11 key nutrients ranged from 24% to 100% in the two groups. In addition, carbohydrate intake was lower than the American Diabetes Association recommendations. Even in a group in which diet has significant health impact, it likely takes more than improved prosthodontic interventions to achieve meaningful dietary benefits.
In a large-scale (N = 255) RCT comparing the effects of mandibular CDs and IODs on nutrition in a general edentulous population, little difference was seen in nutritional status between the two denture treatments.58 Highly reliable and valid assessments of nutritional state were achieved in this study through the use of blood tests sensitive to dietary intake of key nutrients. While there were no differences in nutritional state between patients treated with a new mandibular CD or IOD, participants treated with the IOD reported less chewing difficulty, less avoidance of certain foods, and less required preparation of foods to make it easier to chew compared with those in the CD group.
Clearly, modification of diet and nutritional intake is a significant issue, both in response to national and international concerns with obesity and to the management of diet and nutrition for more fragile elderly patients. Provision of implant-supported mandibular dentures may improve patient perceptions regarding restriction of food types and preparation methods from when they had a CD, but it appears that their nutritional intake is not improved by this change. Behavioral change through counseling remains the primary option to achieve any improvement in nutrition.
Summary of clinical outcome data
The primary factor in impaired mastication is tooth loss, which will continue to be a problem and require prosthetic restoration for the immediate future. Neither implant-assisted nor implant-supported mandibular dentures restore masticatory function to levels seen with intact dentition. Most patients with reasonable denture-bearing surfaces are able to masticate at the same level of effectiveness with either conventional complete dentures, an implant-retained or -supported overdenture in the mandible opposing a conventional or implant-supported maxillary denture, or a fixed hybrid denture in the mandible opposing a conventional or implant-supported prosthesis in the maxilla. Patients with mandibular ridge resorption are more likely to benefit from improved masticatory function with implant-retained or -supported prostheses than with CDs. Although the evidence is limited, there appears to be little improvement in masticatory function with increased implant support over the implant-retained prosthesis.
Patient perceptions of satisfaction with denture treatment, chewing function, comfort, stability, and retention are all improved with implant-retained or -supported prostheses. It is not clear with the current evidence if increased implant support significantly improves patient perceptions of the implant-supported denture beyond the two-implant overdenture. The evidence does not indicate a clear superiority of fixed hybrid prostheses over implant-supported removable prostheses in patient perceptions, where preferences may depend more on individual expectations for esthetics, stability, and convenience.
Summary
As discussed in this chapter, there are limitations to the functional benefits of IOD treatment in patients with reasonably good residual ridges who do not experience difficulty in adapting to CDs. There continues to be somewhat higher initial and maintenance costs for implant prostheses, reducing access to the treatment for financially disadvantaged patients. However, the use of implant-supported overdentures in patients with severe ridge resorption or with chronic tissue irritation and difficulty in adaption to CDs has been shown to be beneficial, both in improved masticatory function and in psychologic impact. Additional implant support, either in the form of an implant-supported overdenture or a fixed prosthesis, does not appear to have a significant impact on mastication efficiency.
References
1. Smith M. Measurement of personality traits and their relation to patient satisfaction with complete dentures. J Prosthet Dent 1976;35:492–503.
2. Smedley TC, Friedrichsen SW, Cho MH. A comparison of self-assessed satisfaction among wearers of dentures, hearing aids, and eyeglasses. J Prosthet Dent 1989;62:654–661.
3. Jonkman RE, Van Waas MA, Kalk W. Satisfaction with complete immediate dentures and complete immediate overdentures. A 1 year survey. J Oral Rehabil 1995;22:791–796.
4. Gjengedal H, Berg E, Boe OE, Trovik TA. Self-reported oral health and denture satisfaction in partially and completely edentulous patients. Int J Prosthodont 2011;24:9–15.
5. Tallgren A. The continuing reduction of the residual alveolar ridges in complete denture wearers: A mixed-longitudinal study covering 25 years. J Prosthet Dent 1972;27:120–132.
6. Atwood DA. Reduction of residual ridges: A major oral disease entity. J Prosthet Dent 1971;26:266–279.
7. Atwood DA, Coy WA. Clinical, cephalometric, and densitometric study of reduction of residual ridges. J Prosthet Dent 1971;26:280–295.
8. Kelly E. Changes caused by a mandibular removable partial denture opposing a maxillary complete denture. J Prosthet Dent 1972;27:140–150.
9. Yeh CK, Rodan GA. Tensile forces enhance prostaglandin E synthesis in osteoblastic cells grown on collagen ribbons. Calcif Tissue Int 1984;36(suppl 1):S67–S71.
10. Sanuki R, Shionome C, Kuwabara A, et al. Compressive force induces osteoclast differentiation via prostaglandin E(2) production in MC3T3-E1 cells. Connect Tissue Res 2010;51:150–158.
11. Nishimura I, Szabo G, Flynn E, Atwood DA. A local pathophysiologic mechanism of the resorption of residual ridges: Prostaglandin as a mediator of bone resorption. J Prosthet Dent 1988;60:381–388.
12. Tallgren A. Changes in adult face height due to ageing, wear and loss of teeth and prosthetic treatment. A roentgen cephalometric study mainly on Finnish women. Acta Odontol Scand 1957;15(suppl 24):7–122.
13. Atwood DA. A cephalometric study of the clinical rest position of the mandible: Part II. The variability in the rate of bone loss following the removal of occlusal contacts. J Prosthet Dent 1957;7:544–552.
14. Carlsson GE, Persson G. Morphologic changes of the mandible after extraction and wearing of dentures. A longitudinal, clinical, and x-ray cephalometric study covering 5 years. Odontol Revy 1967;18:27–54.
15. Jahangiri L, Devlin H, Ting K, Nishimura I. Current perspectives in residual ridge remodeling and its clinical implications: A review. J Prosthet Dent 1998;80:224–237.
16. Klemetti E, Vainio P, Lassila V, Alhava E. Trabecular bone mineral density of mandible and alveolar bone height in postmenopausal women. Scand J Dent Res 1993;101:166–170.
17. Bollen AM, Taguchi A, Hujoel PP, Hollender LG. Number of teeth and residual alveolar ridge height in subjects with a history of self-reported osteoporotic fractures. Osteoporos Int 2004;15:970–974.
18. Ozola B, Slaidina A, Laurina L, Soboleva U, Lejnieks A. The influence of bone mineral density and body mass index on resorption of edentulous jaws. Stomatologija 2011;13:19–24.
19. Nishimura I, Hosokawa R, Atwood DA. The knife-edge tendency in mandibular residual ridges in women. J Prosthet Dent 1992;67:820–826.
20. Nishimura I, Atwood DA. Knife-edge residual ridges: A clinical report. J Prosthet Dent 1994;71:231–234.
21. Von Wowern N, Kollerup G. Symptomatic osteoporosis: A risk factor for residual ridge reduction of the jaws. J Prosthet Dent 1992;67:656–660.
22. Nishimura I, Hosokawa R, Kaplan ML, Atwood DA. Animal model for evaluating the effect of systemic estrogen deficiency on residual ridge resorption. J Prosthet Dent 1995;73:304–310.
23. DeVan MM. Basic principles in impression making. J Prosthet Dent 1952;2:26–35.
24. Sukotjo C, Abanmy AA, Ogawa T, Nishimura I. Molecular cloning of wound inducible transcript (wit 3.0) differentially expressed in edentulous oral mucosa undergoing tooth extraction wound-healing. J Dent Res 2002;81:229–235.
25. Suwanwela J, Lee J, Lin A, et al. A genetic association study of single nucleotide polymorphisms in FGFR1OP2/wit3.0 and long-term atrophy of edentulous mandible. PLoS One 2011;6(1):e16204.
26. Sukotjo C, Lin A, Song K, Ogawa T, Wu B, Nishimura I. Oral fibroblast expression of wound-inducible transcript 3.0 (wit3.0) accelerates the collagen gel contraction in vitro. J Biol Chem 2003;278:51527–51534.
27. Lin A, Hokugo A, Choi J, Nishimura I. Small cytoskeleton-associated molecule, fibroblast growth factor receptor 1 oncogene partner 2/wound inducible transcript-3.0 (FGFR1OP2/wit3.0), facilitates fibroblast-driven wound closure. Am J Pathol 2010;176:108–121.
28. Cardaropoli D, Cardaropoli G. Preservation of the postextraction alveolar ridge: A clinical and histologic study. Int J Periodontics Restorative Dent 2008;28:469–477.
29. Araújo MG, Lindhe J. Ridge preservation with the use of Bio-Oss collagen: A 6-month study in the dog. Clin Oral Implants Res 2009;20:433–440.
30. Araújo MG, Lindhe J. Socket grafting with the use of autologous bone: An experimental study in the dog. Clin Oral Implants Res 2011;22:9–13.
31. Von Wowern N, Gotfredsen K. Implant-supported overdentures, a prevention of bone loss in edentulous mandibles? A 5-year follow-up study. Clin Oral Implants Res 2001;12:19–25.
32. Davis WH, Lam PS, Marshall MW, Dorchester W, Hochwald DA, Kaminishi RM. Using restorations borne totally by anterior implants to preserve the edentulous mandible. J Am Dent Assoc 1999;130:1183–1189.
33. Geertman ME, Boerrigter EM, Van’t Hof MA, et al. Two-center clinical trial of implant-retained mandibular overdentures versus complete dentures—Chewing ability. Community Dent Oral Epidemiol 1996;24:79–84.
34. Garrett NR, Kapur KK, Hamada MO, et al. A randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part II. Comparisons of masticatory performance. J Prosthet Dent 1998;79:632–640.
35. Kimoto K, Garrett NR. Effect of mandibular ridge height on masticatory performance with mandibular conventional and implant-assisted overdentures. Int J Oral Maxillofac Implants 2003;18:523–530.
36. Fontijn-Tekamp FA, Slagter AP, Van Der Bilt A, et al. Biting and chewing in overdentures, full dentures, and natural dentitions. J Dent Res 2000;79:1519–1524.
37. Tang L, Lund JP, Taché R, Clokie CM, Feine JS. A within- subject comparison of mandibular long-bar and hybrid implant- supported prostheses: Evaluation of masticatory function. J Dent Res 1999;78:1544–1553.
38. Feine JS, de Grandmont P, Boudrias P, et al. Within-subject comparisons of implant-supported mandibular prostheses: Choice of prosthesis. J Dent Res 1994;73:1105–1111.
39. Lindquist LW, Carlsson GE. Long-term effects on chewing with mandibular fixed prostheses on osseointegrated implants. Acta Odontol Scand 1985;43:39–45.
40. Carlsson GE, Lindquist LW. Ten-year longitudinal study of masticatory function in edentulous patients treated with fixed complete dentures on osseointegrated implants. Int J Prosthodont 1994;7:448–453.
41. Garrett NR, Kapur KK, Perez P. Effects of improvements of poorly fitting dentures and new dentures on patient satisfaction. J Prosthet Dent 1996;76:403–413.
42. Garrett NR, Kapur KK, Perez P. Effects of improvements of poorly fitting dentures and new dentures on patient satisfaction. J Prosthet Dent 1996;76:403–413.
43. Geertman ME, Slagter AP, van Waas MA, Kalk W. Comminution of food with mandibular implant-retained overdentures. J Dent Res 1999;26:7–13.
44. Humphris GM, Healey T, Howell RA, Cawood J. The psychological impact of implant-retained mandibular prostheses: A cross-sectional study. Int J Oral Maxillofac Implants 1995;10:437–444.
45. Kapur KK, Garrett NR, Hamada MO, et al. Randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part III: Comparisons of patient satisfaction. J Prosthet Dent 1999;82:416–427.
46. Awad MA, Lund JP, Shapiro SH, et al. Oral health status and treatment satisfaction with mandibular implant overdentures and conventional dentures: A randomized clinical trial in a senior population. Int J Prosthodont 2003;16:390–396.
47. Thomason JM, Lund JP, Chehade A, Feine JS. Patient satisfaction with mandibular implant overdentures and conventional dentures 6 months after delivery. Int J Prosthodont 2003;16:467–473.
48. Rashid F, Awad MA, Thomason JM, et al. The effectiveness of 2-implant overdentures—A pragmatic international multicentre study. J Oral Rehabil 2011;38:176–184.
49. Allen PF, McMillan AS, Walshaw D. A patient-based assessment of implant-stabilized and conventional complete dentures. J Prosthet Dent 2001;85:141–147.
50. Allen PF, McMillan AS. A longitudinal study of quality of life outcomes in older adults requesting implant prostheses and complete removable dentures. Clin Oral Implants Res 2003;14:173–179.
51. Boerrigter EM, Stegenga B, Raghoebar GM, Boering G. Patient satisfaction and chewing ability with implant-retained mandibular overdentures: A comparison with new complete dentures with or without preprosthetic surgery. J Oral Maxillofac Surg 1995;53:1167–1173.
52. Raghoebar GM, Meijer HJA, van’t Hof M, Stegenga B, Vissink A. A randomized prospective clinical trial on the effectiveness of three treatment modalities for patients with lower denture problems. A 10 year follow-up study on patient satisfaction. Int J Oral Maxillofac Surg 2003;32:498–503.
53. Pan S, Dagenais M, Thomason JM, et al. Does mandibular edentulous bone height affect prosthetic treatment success? J Dent 2010;38:899–907.
54. Stellingsma K, Bouma J, Stegenga B, Meijer HJA, Raghoebar GM. Satisfaction and psychosocial aspects of patients with an extremely resorbed mandible treated with implant-retained overdentures. A prospective, comparative study. Clin Oral Implants Res 2003;14:166–172.
55. Muller K, Morais J, Feine J. Nutritional and anthropometric analysis of edentulous patients wearing implant overdentures or conventional dentures. Braz Dent J 2008;19:145–150.
56. Sánchez-Ayala A, Lagravère MO, Gonçalves TM, Lucena SC, Barbosa CMV. Nutritional effects of implant therapy in edentulous patients—A systematic review. Implant Dent 2010;19:196–207.
57. Hamada MO, Garrett NR, Roumanas ED, et al. A randomized clinical trial comparing the efficacy of mandibular implant-supported overdentures and conventional dentures in diabetic patients. Part IV: Comparisons of dietary intake. J Prosthet Dent 2001;85:53–60.
58. Awad MA, Morais JA, Wollin S, Khalil A, Gray-Donald K, Feine JS. Implant overdentures and nutrition: A randomized controlled trial. J Dent Res 2012;91:39–46.
