Biomedical subjects

Giulio Preti

Publications and source records attributed to Giulio Preti.

10 recordsLinked to original sources

PubMed2006

Tooth loss and obstructive sleep apnoea.

BACKGROUND: Complete tooth loss (edentulism) produces anatomical changes that may impair upper airway size and function. The aim of this study was to evaluate whether edentulism favours the occurrence of obstructive sleep apnoea (OSA). METHODS: Polysomnography was performed in 48 edentulous subjects on two consecutive nights, one slept with and the other without dentures. Upper airway size was assessed by cephalometry and by recording forced mid-inspiratory airflow rate (FIF50). Exhaled nitric oxide (eNO) and oral NO (oNO), were measured as markers of airway and oropharyngeal inflammation. RESULTS: The apnoea/hypopnoea index (AHI) without dentures was significantly higher than with dentures (17.4 +/- 3.6 versus 11.0 +/- 2.3. p = 0.002), and was inversely related to FIF50 (p = 0.017) and directly related to eNO (p = 0.042). Sleeping with dentures, 23 subjects (48%) had an AHI over 5, consistent with OSA, but sleeping without dentures the number of subjects with abnormal AHI rose to 34 (71%). At cephalometry, removing dentures produced a significant decrease in retropharyngeal space (from 1.522 +/- 0.33 cm to 1.27 +/- 0.42 cm, p = 0.006). Both morning eNO and oNO were higher after the night slept without dentures (eNO 46.1 +/- 8.2 ppb versus 33.7 +/- 6.3 ppb, p = 0.035, oNO 84.6 +/- 13.7 ppb versus 59.2 +/- 17.4 ppb, p = 0.001). CONCLUSION: These findings suggest that complete tooth loss favours upper airway obstruction during sleep. This untoward effect seems to be due to decrease in retropharyngeal space and is associated with increased oral and exhaled NO concentration.

Aged↗

PubMed2005

Retention of luting agents on implant abutments of different height and taper.

OBJECTIVE: The purpose of this study was to evaluate the retention of four cements used to lute metal restorations onto computer designed and manufactured titanium implant abutments of different heights and convergence angles. MATERIAL AND METHODS: Test specimens consisted of metal coping cemented on Procera titanium abutments of 5, 7, and 9 mm of height, and of 0 degrees , 4 degrees , and 8 degrees of convergence angle. The cements used were zinc-phosphate, zinc oxide-eugenole, polyurethane resin with and without vaseline. The samples were tested in a universal testing machine. The mean uniaxial load at point of separation was determined. The results were statistically evaluated with ANOVA. RESULTS: The luting agent, the height, and the taper influence the retention of metal casting on customized CAD-CAM implant abutments. CONCLUSION: The most retentive cement was zinc-phosphate, followed by polyurethane, polyurethane plus vaseline, and zinc oxide-eugenol.

Analysis of Variance↗

PubMed2005

Biological factors involved in the osseointegration of oral titanium implants with different surfaces: a pilot study in minipigs.

BACKGROUND: The stability of titanium implants is determined by the rigid load-bearing connections that are formed by the bone, a process that involves a complex network of cells, pro- and anti-inflammatory mediators, and growth factors. The osseointegration processes at the interfaces of machined and porous implants were studied using molecular and histological techniques. METHODS: Two machined and two porous titanium implants were inserted into the tibiae of four minipigs. The animals were sacrificed at 15, 30, 60, and 90 days post-implantation. The levels of bone morphogenetic protein (BMP)-4, transforming growth factor (TGF)-beta1, and tumor necrosis factor (TNF)-alpha were quantified in the peri-implant osseous samples. The levels of interleukin (IL)-1beta, IL-6, IL-10, and TNF-alpha in the serum were also assessed. RESULTS: Histomorphological analysis showed evidence of bone ossification around the porous implant at 60 days. Surrounding the machined implants, highly sclerotic fibrous pads started the healing response at 90 days, and the levels of TGF-beta1 and BMP-4 began to increase at 60 days, at which time bone ossification around the porous implants was already evident. TNF-alpha was not present in the bone next to the implants. The serum levels of cytokines IL-1beta, IL-6, and IL-10 were not increased. The serum level of TNF-alpha increased during the healing process. CONCLUSIONS: We observed that the levels of BMP-4 and TGF-beta1, which play essential roles in the osteogenesis process, increased earlier around the porous implants than around the machined implants. Similarly, the ossification process was initiated earlier at the surfaces of the porous implants than at the surfaces of the machined implants.

Animals↗

PubMed2004

Growth-associated protein-43 immunoreactivity in human oral mucosa in dentate subjects, in edentulous patients and after implant-anchored rehabilitation.

OBJECTIVES: This study investigates expression of the neural growth-associated protein 43 (GAP-43) in the oral mucosa of (A) normal dentate subjects, (B) edentulous patients rehabilitated with conventional denture and (C) those rehabilitated with mandibular implant-retained overdentures (MIR-OVD), in the long term. This study evaluates morphological changes in the distribution and representation of sensory terminations and corpuscles in the alveolar mucosa under the action of different masticatory or prosthetic loads, in the three clinical groups. MATERIAL AND METHODS: GAP-43 immunoreactivity (-ir) was compared with the distribution of nerves fibres in the mucosa, as visualised using anti-protein gene product 9.5 (PGP 9.5), a general marker for peripheral nerves and terminals. RESULTS: GAP-43-ir was found to be highly expressed in the corium and submucosa in specimens from edentulous subjects wearing conventional denture and presenting a reduced number of PGP 9.5-ir nerves in the mucosa, but not in specimens from control subjects or patients wearing MIR-OVD, which on the contrary show a higher number of PGP 9.5-ir mucosal sensory fibres. CONCLUSION: As the mucosa under traditional denture has been shown to possess reduced innervation and the histological aspect of chronic overloading, these results may be considered indicative of a tentative induction to nerve re-growth in the under-innervated epithelium, or as a response to chronic inflammation. The detection of GAP-43-ir suggests that human oral mucosa presents signs of potential nerve plasticity also in the elderly, and that the type of rehabilitation and the condition of masticatory load transfer to the mucosa have important effects on the nerves underneath.

Adult↗

PubMed2002

Tooth-implant connection: some biomechanical aspects based on finite element analyses.

This study investigated, with the use of two- and three-dimensional finite element analysis, the peri-implant stress that occurred during loading of a tooth that was rigidly connected to a distally placed implant. A fixed bond between the bone and the implant was assumed, while the periodontal ligament was represented by means of three-dimensional nonlinear visco-elastic spring elements. Two different loading conditions were compared in the study: i) an axially directed static load of 50 kg that was applied to the tooth for 10 s, and ii) a transitional load of 50 kg that was applied for 5 milliseconds. Load duration appeared to have a greater influence than load intensity on the stress distribution in the bone around an implant and a rigidly connected tooth. Static load is, therefore, potentially more harmful for peri-implant bone than transitional load. The periodontal ligament seems to play a key role in the stress distribution between a tooth and a rigidly connected implant.

Alveolar Process↗

PubMed2002

Organization of the connective tissue barrier around long-term loaded implant abutments in man.

The study aimed to investigate the connective tissue seal and the spatial organization of collagen fibers around long-term loaded implants in man. Block specimens containing smooth titanium implant abutments and the surrounding supracrestal connective tissue were obtained from patients rehabilitated for at least 1 year with implant-retained overdentures or implant-supported fixed prostheses and were histologically investigated. The histological features of the connective tissue around long-term loaded titanium abutments were specific: the tissue was rich in collagen fibers, organized in bundles, presenting a constant spatial arrangement, similar to that reported in animal studies. Circular fibers, the most numerous, were located externally, and longitudinal fibers internally. Radial fibers inserted on the abutment surface, similar to those of the periodontal system, were not observed in any case. No histological differences were found between tissue sampled around implants supporting a fixed restoration and those anchoring an overdenture.

Aged↗

PubMedDate not supplied

Marginal adaptation of fixed prosthodontics: a new in vitro 360-degree external examination procedure.

PURPOSE: This study evaluated the marginal fit of experimental and custom-made fixed prosthetic restorations through a new 360-degree external examination. The minimum number of gap measurements required to produce relevant results for gap analysis was also investigated. MATERIALS AND METHODS: The marginal fit of six experimental and eight custom-made crowns was observed microscopically by means of a mechanical device, and software was employed to measure the gap. Two crowns, chosen from among the 14 previously evaluated, were reanalyzed to determine the minimum number of gap measurements required to produce significant results for gap analysis. RESULTS: The precision obtained with the custom-made crowns differed from that of the experimental specimens. The minimum number of measurements required to produce a sample mean value within +/- 5 microm of the mean, calculated over 360 measurements, taking standard error of the means < or = 4 microm, was 18 for experimental and 90 for custom-made crowns, for both equidistant measurement spacing and randomly selected points. CONCLUSION: Differences in fit between experimental specimens and custom-made ones showed that experimental results might not always be obtained in clinical practice. Within the limitations of the protocol of this study, the minimum number of measurements required to ensure relevant results for gap analysis was 18 for experimental and 90 for custom-made crowns.

Crowns↗

PubMedDate not supplied

Obstructive sleep apnea, depression, and oral status in elderly occupants of residential homes.

PURPOSE: Obstructive sleep apnea syndrome (OSAS) is a sleep disorder characterized by repetitive episodes of upper airway obstruction. Recently, it has been suggested that edentulism worsens sleep apnea; sleeping without dentures is associated with a significant increase in the apnea-hypopnea index. OSAS is also related to depression. The aim of this study was to assess, in a group of elderly occupants in residential homes in the Turin district of Italy, (1) the prevalence of key symptoms and indicators of OSAS and the prevalence of depressive feelings; (2) how the reduction of vertical dimension of occlusion (VDO) influenced the onset of OSAS; and (3) whether a relationship between OSAS and depression was present. MATERIALS AND METHODS: The sample population consisted of 403 people (77% men, 23% women; age range, 65 to 90 years). The subjects underwent the Italian version of the Mini Mental State Examination (MMSE) to assess their mental condition. The remaining collaborating subjects completed 2 questionnaires to assess the risk of OSAS (Berlin Questionnaire) and depressive feelings (Beck Depression Inventory). RESULTS: Of the 403 elderly residents initially evaluated with the MMSE, 97 were excluded from the study, reducing the sample size to 306 subjects (75% women, 25% men; mean age +/- standard deviation, 83.12 +/- 11.10 years). The analysis of these data revealed a statistically significant association between the risk for sleep apnea and the VDO (P < .0001), and between sleep apnea and depressive feelings (P < .05). CONCLUSION: This study revealed that inadequate VDO is closely associated with the risk of OSAS, and that depressive feelings are more present if there is a high risk for OSAS.

Aged↗

PubMedDate not supplied

Mandibular implant-retained overdentures with 2 different prosthetic designs: a retrospective pilot study on maintenance interventions.

This retrospective study aimed to investigate whether a mandibular implant-retained overdenture designed to counteract the rotation of the denture might influence the clinical outcome, as evaluated through the prosthetic maintenance interventions. The amount of repairs and relines of the mandibular and maxillary dentures required in an experimental group (6 patients wearing an implant-retained overdenture with a metal frame counteracting the rotation) and a control group (6 patients wearing an implant-retained overdenture allowing the rotation) was compared. Both mandibular and maxillary dentures needed few repairs or relines. The 2 types of dentures showed a similar number of maintenance interventions.

Dental Alloys↗

PubMedDate not supplied

A preliminary in vivo trial of load transfer in mandibular implant-retained overdentures anchored in 2 different ways: allowing and counteracting free rotation.

This in vivo pilot methodologic study used 3 patients to investigate load transfer in mandibular implant-retained overdentures anchored in 2 different ways: allowing (gap condition) and counteracting (contact condition) free rotation. Load cells and strain-gauged abutments were used to evaluate occlusal load, load transmitted to the nonworking-side mucosa, and stress on the working-side abutment, in both contact and gap conditions. The occlusal load was reduced and load was shifted from abutments to mucosa in the gap versus the contact condition. In the contact condition, patients reported more comfort and felt that they could exert greater occlusal force.

Bite Force↗