You will be presented with the full text of a biomedical research paper. Please write an abstract for this paper. Your response should include the abstract and no additional text.

Paper text:
increased life expectancy is one of the greatest global public health challenges in developed countries . in italy
, the proportion of the population aged 65 exceeds 21% . in western europe , the proportion exceeds 16% , and in the us , australia , and oceania , it is 13%.14 in parallel with changes in the age pyramid ,
age - related challenges arise , and interest in combating visible signs of skin aging increases .
aging of the face through a dynamic process characterized by the degeneration of both the soft tissues and the bone structure leads to an altered relationship between these components.5 skin aging is a gradual , natural process classified as intrinsic or extrinsic , and involves genetic , hormonal , and environmental mechanisms .
intrinsic aging , also called chronologic aging , may be influenced by exogenous factors such as smoking , alcohol consumption , and exposure to ultraviolet radiation , which are considered the main factors of extrinsic aging.6 wrinkle formation is a consequence of these processes.712 requests for cosmetic procedures with permanent or temporary filler to reduce the number and depth of wrinkles and to provide an appropriate volume to the lips13,14 are increasing with variable results.15 reports of more or less serious complications are also increasing in number , however , even in the case of safe molecules such as hyaluronic acid.1618 degenerative processes involving the teeth ( tooth loss , poorly executed prosthetic rehabilitation , neglect of oral hygiene , etc ) also contribute to aging the appearance of a face.19 in fact , a face devoid of a smile with complete dentures appears more aged than one with a complete set of teeth , both subjectively and objectively with regard to the facial structures.20 in addition , the condition of edentulism is associated with a well - known progressive centripetal resorption of the alveolar process of the maxillary bones,21 with reduced support and stretching of the perioral tissues exerted by the teeth and underlying bone , and consequent worsening of wrinkles and lip volume .
to evaluate the effect of rehabilitation through removable implant - retained dentures on perioral wrinkles .
this prospective cohort , single - center trial , conducted in accordance with good clinical practices in human beings , involved 31 subjects who underwent rehabilitation of the upper and lower jaws with implant - retained dentures.22 this study was approved by the ethic committee of pavia state , fondazione irccs policlinico  san matteo  , pavia , italy ( document 09/21/2016 , n. 20020001513 ) .
the subjects were enrolled consecutively from among those who accessed the oral surgery and implantology service of the department of clinical surgical , pediatric , and diagnostic sciences at the university of pavia .
the surgical23 and prosthetic procedures used for all patients were those typically used by our team and included , briefly : medical history and clinical examination , obtaining consent , radiographic and hematologic evaluation , antibiotic prophylaxis , implant surgery , submerged healing for 68 weeks , second surgery , dental impressions , prosthetic proof - of - concept , and final restoration .
the skin at the perioral tissue level was intact in all subjects , and none of the patients were taking topical or systemic medications or substances that could interfere with the evaluation of perioral wrinkles .
patients were informed about the purpose of the research and the use of any obtained photographs in which patients would not be recognizable .
all patients freely provided their written consent to be included in this study and to the use of facial images for the purposes of the study .
perioral wrinkles and lip volume were evaluated by comparing photos at the beginning and end of the study for each case examined . the scale proposed by lamperle et al24 was used for evaluation of perioral wrinkles , in which a score from 0 to 5 is assigned according to the increasing severity of the wrinkles .
lip volume was graded according to the lip fullness scale,25 in which a score from 0 ( very thin ) to 4 ( full ) is assigned .
the patients were photographed before and after the rehabilitation program to compare the aesthetics of the perioral soft tissues with and without the final prosthesis in place . in this study , the following parameters were analyzed : upper and lower radial lip lines , marionette lines , upper and lower lip fullness , nasolabial folds , corner of the mouth lines , and labiomental crease .
personal data and medical history were also collected , with an emphasis on intrinsic and extrinsic factors that promote skin aging:26 prolonged periods of sun exposure , smoking , diet , and hormone replacement therapy .
the photographs were obtained using a professional digital slr camera fujifilm s5 pro ( fujifilm corporation , tokyo , japan ) , with a nikkor 35 mm ( nikon corporation , tokyo , japan ) fixed focal length lens . the images were recorded in high definition and saved in raw format to allow for the optimum setting of image parameters in post - processing .
two full - face photographs for each patient were obtained : one with and one without the dentures .
the images were obtained of the frontal face position , with the mouth of the patient in rest position . to avoid bias due to the shooting point position , the camera was mounted on a tripod and positioned 1 m from the patient s face , at the height of the mouth .
photographs of the smile were not obtained to avoid the possibility of biasing the observers .
once taken , the pictures were cut to place only the perioral area in the foreground ( figure 1 ) .
the images were identified by a label code and randomly inserted into a powerpoint ( microsoft corporation , redmond , wa , usa ) presentation with a black background .
after proper training , two observers independently and blindly evaluated the clinical images using an imac computer ( apple , cupertino , ca , usa ) with a 27 monitor in a dark room .
data were collected using a diagram drawn by the authors ( figure 2 ) and then input into an excel ( microsoft corporation , redmond , wa , usa ) spreadsheet .
the collected data were statistically analyzed using r core team ( 2013 ) ; r : a language and environment for statistical computing ( r foundation for statistical computing , vienna , austria ; http://www.r-project.org/ ) . because the results were scored subjectively , the observations were treated as ordinal qualitative variables using the wilcoxon test of ranks for paired data to determine the statistical significance .
in the period between january 2012 and june 2016 , 31 patients ( 15 males ) , between 47 and 77 years of age ( mean  standard deviation , 62.138.69 years ) , were enrolled at the service of oral surgery and implant dentistry of the department of clinical surgical , pediatric , and diagnostic sciences at the university of pavia .
all patients completed the study , and 31 mandibular and maxillary implant - prosthetic rehabilitations were completed .
rehabilitation with overdentures produced statistically significant improvement in the upper and lower radial lip lines , marionette lines , upper and lower lip fullness , nasolabial folds , and corner of the mouth lines ( table 1 ; figures 39 ) .
this study evaluated the effect of implant - retained denture rehabilitation22 on perioral wrinkles in edentulous patients .
the rating scale used is simple to read and facilitates comparison of the photographs of the observed cases .
moreover , the high definition photographs obtained with a professional camera allowed for better visualization of wrinkles because the images could be magnified to highlight the details of the observed elements . statistical analysis revealed that implant - retained denture rehabilitation significantly improved the aesthetics of the perioral soft tissues with regard to almost all wrinkle types evaluated .
statistically significant improvements were observed for the upper and lower radial lip lines , marionette lines , upper and lower lip fullness , nasolabial folds , and the corner of the mouth lines .
numerous studies have evaluated oral and perioral aesthetics , focusing on the form,27,28 structure,29 color,30 and position31,32 of the teeth , and the influence of prosthetic rehabilitation on the aesthetics of the smile.33 this is the first study to evaluate the influence of implant - retained rehabilitation on the appearance of perioral wrinkles and lip volume . with aging ,
the whole organism undergoes structural changes and at the same time the skin undergoes significant alterations due to intrinsic or extrinsic factors .
these processes result in the loss of elasticity and firmness of the tissue , leading to the formation of wrinkles .
in addition to this damage , loss of the teeth and consequent resorption of alveolar bone tissues considerably worsens the overall appearance of the face , with an accentuation of the typical features of aging : wrinkles , skin laxity , loss of tone , a decreased intermaxillary vertical dimension , mandibular prognathism , and lowering of the nasal tip.19,20 implant - retained denture rehabilitation allows  in addition to the restoration of masticatory function and the intraoral aesthetic  for restoration of the volume of the alveolar process and thus leads to optimal support of the perioral soft tissues .
therefore , proper prosthetic rehabilitation may help to improve the aesthetics of the perioral skin , reducing the amount and size of wrinkles involved in face aging and providing greater support to the lips .
moreover , besides the advantages of being less expensive than a full - arch implant - supported fixed prosthesis and providing greater stability compared to the traditional removable denture , overdentures are indicated even in cases in which the patient desires aesthetic improvement of the perioral soft - tissues .
in addition , rehabilitation with overdentures allows for easier maintenance of hygiene around implants compared to a full - arch implant - supported fixed prosthesis.34 while traditional removable dentures may also somewhat restore lost volume and provide optimum support to the soft tissues , these benefits are limited by the need to optimize stability . in the case of overdentures , which have extremely superior stability , modeling of the prosthetic flanges and positioning of the teeth
can be oriented not only to the recovery of optimal masticatory function , but also to the appropriate restoration of lost volume and support of soft tissues .
the results of this study highlight the importance of a comprehensive assessment that includes the dental situation of patients in need of an aesthetic medical intervention to improve the appearance of perioral tissues .
further research should be conducted to assess whether there are significant differences between the perioral aesthetics of full - arch implant - supported fixed prostheses and implant - retained denture rehabilitation .
a global treatment plan that aims to restore facial aesthetics in fully edentulous patients should consider implant - retained denture rehabilitation to provide adequate deep support of the perioral soft - tissue . in these patients ,
the use of aesthetic medicine techniques such as fillers may benefit from dental rehabilitation . in fully edentulous patients
backgroundthe onset of perioral wrinkles often prompts patients to request treatment . 
 this aesthetic deterioration linked to aging may be associated with tooth and alveolar bone loss in fully edentulous patients.purposeto evaluate perioral wrinkles before and after maxillary and mandibular rehabilitation with implant - retained dentures in fully edentulous patients.methodsin this prospective cohort , single - center , blinded study , patients requiring maxillary and mandibular rehabilitation with implant - retained dentures were enrolled . 
 the patients were photographed in the same position before and after oral rehabilitation . 
 wrinkles were evaluated in the photographs by blinded observers using validated rating scales . 
 the following parameters were analyzed : upper and lower radial lip lines , marionette lines , upper and lower lip fullness , nasolabial folds , corner of the mouth lines , and the labiomental crease . 
 statistical analysis was performed using the wilcoxon signed ranks test for paired data , with p<0.05 considered significant.resultsupper and lower implant - retained dentures were applied in 31 patients ( 15 males ; mean  standard deviation age 62.138.69 years , range 4777 years ) . 
 the oral rehabilitation procedures significantly improved ( p<0.05 ) the upper and lower radial lip lines , marionette lines , upper and lower lip fullness , the nasolabial folds , and the corner of the mouth lines.conclusionmaxillary and mandibular rehabilitation with implant - retained dentures in fully edentulous patients improves perioral aesthetics . 
 patients requiring oral rehabilitation and desiring perioral aesthetic improvement could benefit from treatment with this type of prosthesis .