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General introduction and aims of the study

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Chapter 1

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General introduction and aims of the study

General introduction The burden of being edentulous, and the functional limitations caused by this phenomenon have been committed to paper since ancient times. The Roman poet Horace (Quintus Horatius Flaccus, 65-8 BC) wrote in one of his lyrical poems that a witch, named Canidia, ran so fast that her dentures fell out (Fairclough, 1926); “At illae currere in urbem; Canidiae dentes, altum Saganae caliendrum excidere atque herbas atque incantata lacertis vincula…..”*

The loss of all the teeth not only complicates the comminution of food, but also can spoil the social aspects of sharing a meal with others. Furthermore, it interferes with producing comprehensible phonemes, thus invalidating speech, which may induce feelings of uncertainty and shame to its owner. The absence of teeth compromises the facial appearance, undermining self-esteem and thus the well-being of those confronted with edentulousness. The absence of teeth has always been the ‘raison d’être’ of prosthetic dentistry, and already in the ancient civilization of the Incas and the Etruscans examples of subtle tooth replacement were found (Ring, 1985a). The first complete dentures were cut out of wood, bone or ivory, lacking correct fit because the making of models according to impressions of the edentulous jaws was not yet known (Fauchard, 1728). That these techniques not always led to satisfying results * “Then back to the city they fled in a hurry. Then how Canidia dropped her false teeth, how Sagana’s enormous wig came undone, how their herbs and their ritual bracelets went flying...”

can best be illustrated by the first president of the United States of America, George Washington (1732-1799), who after a long period of toothaches became one of the best documented edentulous patients complaining about the pain and discomfort he suffered from wearing dentures made of hippopotamus bone (Ring, 1985b). In the next centuries the development of materials and new techniques led to major improvements in the field of complete denture prosthodontics: the production of artificial teeth, impression and mold making, and the possibility of curing synthetic materials are milestones in the development of contemporary complete dentures (Wynbrandt, 1998). Although these innovations improved the care for edentulous patients enormously, still a substantial percentage of the population of denture wearers reports functional problems (Kalk, 1979). The lack of stability and retention, especially of the lower denture, are responsible for the majority of these complaints. Problems associated with an atrophied mandible have been a challenge for oral and maxillofacial surgeons and prosthodontists for a long time. Numerous surgical techniques have been developed to improve the starting point for prosthetic rehabilitation (Jennings, 1989; McCord et al., 1992). Most of these procedures only temporarily improve the local anatomy. In addition, a considerable morbidity has to be taken into account (Stoelinga et al., 1986). Since the first well documented studies appeared about the firm contact that was possible between a loaded dental implant, made of a bioinert material and human living bone, ‘osseointegration’, a term coined by P.I. Brånemark, became the basic concept for a new discipline in dentistry, i.e., dental implantology (Brånemark et al., 1977; Brånemark,

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Chapter 1

General introduction and aims of the study

1983). The widespread use of dental implants to provide an anchorage for fixed and removable prostheses can be noted as a historical breakthrough in prosthetic dentistry. In the moderately resorbed edentulous mandible dental implants can be applied to support a fixed bridge or to retain an overdenture. Because of the relative simplicity, the high success percentages, and the favorable cost-effectiveness ratio the great majority of edentulous patients in the Netherlands undergoing implant treatment receive two to four implants in the interforaminal area followed by a removable implant-retained overdenture (Cune et al., 1995; Batenburg et al., 1998). This treatment concept has been evaluated in several studies (Raghoebar et al., 2000; Meijer et al., 2001).

Objectives of this study When the edentulous mandible is extremely resorbed, i.e., with symphyseal height of 12 mm or less, there is no ‘communis opinio’ about the treatment strategy. Therefore, we prospectively compared the clinical behavior, radiographic aspects, patient satisfaction and masticatory function of three strategies to treat the extremely resorbed mandible. The three treatment strategies were: I an overdenture retained by a transmandibular implant (Bosker et al., 1991); II augmentation of the mandible using an autologous bone-graft followed three months later by inserting four endosseous implants and an overdenture (Satow et al., 1997); III the installation of four, short endosseous implants to support an overdenture (Triplett et al., 1991). 14

The general aim of this study was to compare the outcomes of these treatment strategies and gain insight into the (dis)advantages of each in order to obtain scientifically based considerations for clinical decision making in the treatment of patients with an extremely resorbed mandible. This can finally contribute to improved rehabilitation of patients with an extremely resorbed mandible. The specific aims were: • to provide an overview of the literature concerning implantologic interventions with regard to the edentulous mandible, with special emphasis on the literature concerning overdenture treatment of the severely resorbed mandible (Chapter 2); • to retrospectively evaluate the outcomes of ten patients treated with interposition of a bone graft (iliac crest) followed three months later by inserting four endosseous implants and overdenture treatment (Chapter 3); • to assess the applicability of the lateral oblique radiograph for bone height measurements of the edentulous mandible in a preclinical study (Chapter 4); • to retrospectively assess the feasibility of short endosseous implants in combination with implant-retained overdentures in patients with an extremely resorbed mandible (Chapter 5); • to prospectively compare the clinical and radiographic aspects of three treatment strategies in patients with an extremely resorbed mandible, at the beginning of prosthetic loading, and 12 and 24 months thereafter (Chapter 6, 7); • to prospectively compare the effects on patient satisfaction and psychosocial aspects of three treatment strategies in patients with an extremely resorbed mandible (Chapter 8).

•

to assess masticatory function (patient-based and laboratory-assessed) in patients with an extremely resorbed mandible, and to prospectively compare the effects of three treatment strategies on masticatory function (Chapter 9).

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Chapter 1

REFERENCES

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Maxillofac Surg 26:358-364. Stoelinga PJ, Blijdorp PA, Ross RR, De Koomen HA, Huybers TJ (1986). Augmentation of the atrophic mandible with interposed bone grafts and particulate hydroxylapatite. J Oral Maxillofac Surg 44:353-360. Triplett RG, Mason ME, Alfonso WF, McAnear JT (1991). Endosseous cylinder implants in severely atrophic mandibles. Int J Oral Maxillofac Implants 6:264-269. Wynbrandt J (1998). The excruciating history of dentistry. New York: St. Martin’s Press.