*Implant-Retained Maxillary and Mandibular Overdentures - A Solution for Completely… DOI: http://dx.doi.org/10.5772/intechopen.99575*

in edentulous dental arches together with the desire to improve esthetic appearance [49]. Consequently, they are indicated in patients suffering from severe morphological destruction of denture supporting regions with significant loss of denture retention and stability (**Figures 2** and **3**), those with poor oral muscular coordination and low

#### **Figure 3.**

*Three-dimensional measurement of mandibular bone in completely edentulous patient. The resorption of the mandibular residual arch is not so progressive, therefore the placement of 4 implants in the frontal region is indicated.*

#### **Figure 4.** *Vestibular view of 2 implant-retained mandibular overdenture.*

tolerance of soft underlying tissues, having parafunctional habits increasing soreness and instability of the conventional restorations or severe gag reflexes [50].

This type of removable prosthodontic rehabilitation is also strongly recommended in patients with unrealistic conventional prosthodontic expectations and those having psychological problems in wearing removable dentures, even when adequate retention and stability are present in the function [50].

This type of implant-prosthodontic rehabilitation offers several advantages such as need for less implants resulting in lower component costs and less expensive treatments for the patient, easy handling and home care maintenance, achieving extremely high level of facial esthetics by labial acrylic flanges and denture teeth replacing missing bone structure and avoiding parafunctions by removing dentures at night (**Figures 4** and **5**).

The results of the trial reported in Feine et al. and Grandmont et al. suggested that many patients having the chance to compare both fixed and removable

**Figure 5.** *Oral view of 2 implant-retained mandibular overdenture.*

**Figure 6.** *Individual tray, functional imporession and laboratory analogs for 4 implant-retained mandibular overdenture.*


**2.2. Impregnation method**

The titania has been employed as a photocatalyst in several photocatalytic reactions due to its high photoactivity, low cost, low toxicity and good chemical and thermal stability [1–3]. However, its large energy band gap inhibits it from being active under UV light [31–35]. The solar spectrum consists of only 4–5% UV light and around 40% visible light [31].

to improve the photocatalytic efficiency of TiO2

has been attempted. The metal doping agents introduced for TiO2

irradiation is necessary. The modification by non-metal [36–51] and metal [52–83] doping

metals (Fe, Cu, Cr, Co, and Ni) [52–56] and noble metals (Ag, Au, Pd, and Pt) [57–83]. Among the noble metals, silver has received considerable interest due to its additional potential as an antibacterial agent [84]. The importance of medical applications of metal-

manufacturing silver-doped titania. There are ongoing works related with the use of Ag for possible medical devices [79], dental implants [78, 79], food packagings [80], air conditioning filters, and so on [79]. Some works focus on bacterial inactivation [34, 63] and dye waste treatment under visible light irradiation [66, 67, 81–83]. Hence, the preparation and

The sol-gel method involves the interaction of titania sol with silver ion the solution, which forms a gel. The gel is heated at a low temperature to evaporate the solvent followed by calcination at high temperature [31, 35, 72, 73, 78, 80, 82, 83]. The main precursor of titania is com-

Titania sol is prepared by mixing TTip solution in ethanol and water accompanied by stirring vigorously at room temperature for about 15 min. During the dissolution of TTip in the ethanol medium, an exchange of propyl group from TTip with ethyl group from the ethanol to yield titania tetra ethoxides takes places by the release of propanol. Titanium tetra ethoxide

sol of silver. Finally, the silver sol is added dropwise to the titania sol with stirring, where transparent titania sol changes its viscous yellow solution. The reaction between titania sol

4 + C2 H5 O − AgTi (OH)

is frequently employed [31, 72, 75, 77, 80, 82, 83]; however, silver acetylacetonate

solution is mixed with ethanol and stirred [31, 72, 75, 77, 80, 82, 83], giving the

monly liquid titanium(IV) isopropoxide (TTiP) with a chemical formula of Ti(OC3

H9 ) 4

as a photocatalyst under sunlight irradiation is limited.

under sunlight visible

H7 ) 4 [31, 35,

[6–11] attracts researchers to think of

[82, 83] is also potential. For silver starting mate-

3 − Ag + C2 H5 OH (1)

.

are transition

Therefore, the efficiency of TiO2

332 Titanium Dioxide - Material for a Sustainable Environment

characterization of the TiO2

**2. Preparation of TiO2**

72, 75], but titanium n-butoxide (Ti(OC4

and silver sol is commonly written as follows:

is also chosen sometime [35].

Ti (OH)

**2.1. Sol-gel**

rial, AgNO3

The AgNO3

lic silver [85, 86] and antibacterial activity of TiO2

**-AgNP**

is hydrolyzed in acidic medium to form sol titanol of Ti(OH)4

Modification of TiO2

on TiO2

The synthesis of TiO2 -AgNP by impregnation method is carried out by stirring the solution of AgNO3 mixed with the suspension of TiO2 in water for 24 h. The solvent is later removed by drying at 150°C followed with calcination of the product at 500°C [68]. Some modifications in the impregnation method such as the use of capping agent [74] and combustion method [63, 64] are also possible.

The modification starts with silver nanoparticles preparation in polyvinylpyrrolidone (PVP) as a capping agent. For this purpose, the AgNO3 solution is added to methanol and is mixed with PVP. The mixture is refluxed for 3 h at 110°C to give a yellow-orange color solution. The solvent was evaporated at 55°C, and the obtained Ag nanoparticles were dispersed into ethanol and thoroughly washed with hexane and ethanol. The Ag nanoparticles are redispersed into the ethanol under sonication, and TiO2 powder is added to the solution. This mixture is sonicated for 3 h and is dried at 60°C to remove the solvent followed temperature rise to 90°C [74].

The combustion method is carried out by heating a mixture of AgNO3 , titanyl nitrate and glycine as fuel in the muffle furnace at 150°C for 2 h [63, 64]. The remaining solid from the combustion is supposed to be TiO2 -AgNP.


*Edited by John Tiefenbacher*

Perspectives on Nature Conservation demonstrates the diversity of information and viewpoints that are critical for appreciating the gaps and weaknesses in local, regional and hemispheric ecologies, and also for understanding the limitations and barriers to accomplishing critical nature conservation projects. The book is organized to emphasize the linkages between the geographic foci of conservation projects and the biological substances that we conceptualize as "nature", through original research. The reader moves through perspectives of diminishing spatial scales, from smaller to larger landscapes or larger portions of the Earth, to learn that the range of factors that promote or prevent conservation through the application of scholarship and academic concepts change with the space in question. The book reflects disciplinary diversity and a co-mingling of science and social science to promote understanding of the patterns of, pressures on and prospects for conservation.

ISBN 978-953-51-0033-1

Perspectives on Nature Conservation - Patterns, Pressures and Prospects

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3.5.2. Suitability

Clinicians expressed that digital care visits were not always a suitable form of care for some patients. Studies have found that digital care visits were less applicable for new patients [38,50]. This also applies to patients that have musculoskeletal, skin [38,50], pediatric problems, acute and severe health issues [38,51], or conditions that certainly require physical examination [35]. They were also unsuitable for patients with severe mental problems such as paranoia, psychosis, etc. [46]. Medical oncology professionals noted that digital care visits were inappropriate for sensitive conversations with the patient, such as for delivering bad news [51].

#### 3.5.3. Technical Issues

Technical issues may become a serious barrier to providing quality care. In ten of twenty-eight studies, authors reported that healthcare professionals had encountered connectivity issues. Lost connection [36,45,51,52,60], difficulty logging on [46], patients not being able to connect [42], poor or unstable internet connection [50,60], over half the clinicians in Mammen et al. and Yu et al. indicated they experienced audio, video, and connectivity issues [53,58]. Healthcare professionals from other studies also expressed they had problems with poor quality sound or video during the visits, which affected the overall quality of the consultation as it was more difficult to communicate and assess the patient [42,46,52,60,61].