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ePaper created 2017-03-17, 12:34:42 | version 1.38.0
industry | Fig. 3 Fig. 4 Fig. 5 Fig. 6 tory but also the general stability of the denture is a crucial point, since it is decisive for a better patient acceptation of the prosthesis. Generally, in an edentulous patient a large and well-preserved ridge with steep sides and a correct amount of resilient mucosa is considered to be a pre- requisite for a good seal and thus stability. Indeed, a well-preserved bone crest represents a good me- chanical retention to the horizontal forces that are applied to the prosthesis. With a completely flat ridge instead, the prosthesis lacks any kind of retention. In this situation, the physical mechanisms of adhesion and cohesion, and the stabilising function of the mus- cles become clearly predominant (Fig. 4). These considerations suggest that the presence of physical factors distinguished in adhesion and cohe- sion forces are a prerequisite for a stable denture, de- void of any type of mechanical anchoring. Adhesion and cohesion forces act in the interface between prosthesis and mucosa, and reach the maximum ex- pression when the surface of the prosthesis is as wide as possible and the space between the denture base and the mucosa is as thin as possible. Mucous-supported dentures The success of a treatment with an osteo-mu- cous-supported denture depends on the patient’s ac- ceptance and his/her sufficient adaptability to over- come unavoidable limitations that a prosthesis provides.3 Accordingly, the ability of the patient to develop newly acquired reflexes plays a key role. Any- way, this ability decreases with the increasing of age, resulting in a reduction to adapt and deal with any in- tervention in the oral cavity. This process is a fact that can threaten their physical and mental integrity. Fig. 3: P riority required was not to increase stability but to restore A number of factors like denture wearing, chewing and phonetic discomfort contribute to the patient’s satisfaction or not.4 Often patients complain about the difficulty of eating hard foods. In consequence, they develop the habit of avoiding them, which is a well-described habit (Fig. 5). In order to increase the masticatory efficiency of the mandible, the position- ing of implants represent an undeniable benefit. How- ever, there are few objective evaluations published that suggest this to be the better solution compared to the traditional technique (Fig. 6). Such studies would allow making more rational de- cisions about the best practice to put in act, in order to satisfy the patient’s needs and to be in line with the widespread conviction to base a treatment on scien- tific evidence. The evidence of the biological success and psychosocial satisfaction lead to a general con- sensus that identifies the overdenture retained with two implants as the best choice for an edentulous mandible (Fig. 7). Implant-based dentures The opinion of implant-based denture as best prac- tice has been questioned. Some authors, for instance, claim that this evidence does not confirm the asser- tion that the implants are necessary or advisable for all edentulous patients. Literature shows that the pa- tient's acceptance of specific therapeutic modalities is modified by social and cultural influences, financial resources and adaptability. There is also no evidence of a single mode of treatment for the edentulous the smile line and the lip support to achieve a younger appearance of the patient’s face. Fig. 4: Even with critical bone ridges prosthesis can be constructed with a good seal, if the supporting surface is wide enough and with a thin gap between denture base and mucosa. Fig. 5: The masticatory efficiency depends on the stability of the prosthesis; the more stable the prosthesis is the greater can be the developed forces. Fig. 6: The widespread success of this evidence has led to a general consensus for a standardised proposal for overdentures anchored to two implants. implants 1 2017 33