Role of rhBMP-7, Fibronectin, And Type I Collagen in Dental Implant Osseointegration Process: An Initial Pilot Study on Minipig Animals.

BACKGROUND: The biological factors involved in dental implant osseointegration need to be investigated to improve implant success. METHODS: Twenty-four implants were inserted into the tibias of six minipigs. Bone samples were obtained at 7, 14, and 56 days. Biomolecular analyses evaluated mRNA of BMP-4, -7, Transforming Growth Factor-ß2, Interleukin-1ß, and Osteocalcin in sites treated with rhBMP-7, Type 1 Collagen, or Fibronectin (FN). Inflammation and osteogenesis were evaluated by histological analyses. RESULTS: At 7 and 14 days, BMP-4 and BMP-7 increased in the sites prepared with rhBMP-7 and FN. BMP-7 remained greater at 56 days in rhBMP-7 and FN sites. BPM-4 at 7 and 14 days increased in Type 1 Collagen sites; BMP-7 increased from day 14. FN increased the TGF-ß2 at all experimental times, whilst the rhBMP-7 only did so up to 7 days. IL-1ß increased only in collagen-treated sites from 14 days. Osteocalcin was high in FN-treated sites. Neutrophilic granulocytes characterized the inflammatory infiltrate at 7 days, and mononuclear cells at 14 and 56 days. CONCLUSIONS: This initial pilot study, in a novel way, evidenced that Type 1 Collagen induced inflammation and did not stimulate bone production; conversely FN or rhBMP-7 showed neo-osteogenetic and anti-inflammatory properties when directly added into implant bone site.

TNF-alpha TGF-beta2 and IL-1beta levels in gingival and peri-implant crevicular fluid before and after de novo plaque accumulation.

AIMS: The aim of this split-mouth study was to investigate levels of tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta2) and interleukin-1 beta (IL-1beta) in gingival crevicular fluid (GCF) and peri-implant crevicular fluid (PICF) after a 21-day-period of de novo plaque accumulation in the same patient. MATERIAL AND METHODS: In 25 patients, samples of GCF and PICF were collected in the sulcus of the tooth and of the implant after professional hygiene. After the no-hygiene phase (21 days), second samples of GCF and PICF were taken. Third samples were collected after 69 days of re-establishment oral hygiene techniques. The crevicular fluids were used to determine the volume and the levels of TNF-alpha, TGF-beta2 and IL-1beta. RESULTS: The volume of the crevicular fluids increased significantly after 21 days of plaque accumulation around teeth and implants and decreased significantly by 69 days. TNF-alpha and TGF-beta2 did not change significantly among the three different samples. A significant increase of IL-1beta was observed after plaque accumulation around the teeth GCF, whereas in the PICF the increase was not statistically significant. CONCLUSIONS: These data suggest that increased volumes of GCF and PICF could be useful markers of early inflammation in gingival and peri-implant tissues. In the presence of de novo plaque, implants showed lower, and nearly significant, levels of IL-1beta compared with teeth.

A new clinical method for evaluating the closest speaking space in dentulous and edentulous subjects: a pilot study.

This study proposes a new clinical procedure for measuring the closest speaking space (CSS) and compares it with an instrumental method. The study population included 15 edentulous and 10 dentulous subjects free of systemic disease, speech defects, or masticatory system dysfunction. For all subjects, the CSS was measured using clinical and instrumental methods. The clinical method utilized polyvinyl siloxane, commonly used for interocclusal records, injected on the occlusal surface of the premolars just before the pronunciation of a word containing the consonant sound "s" 3 times. The instrumental method used a kinesiograph. Statistical analysis was performed using 1-way repeated-measures analysis of variance and the Student t test for paired data. There was no statistical difference between the clinical and instrumental methods of determining CSS. Within the limitations of this study, based on a small sample, the new simpler and less expensive method to record the CSS should be considered and further investigated.

A new coping for overdentures. Part 2: Preliminary results of a clinical study.

The aim of this study was to evaluate a new type of coping used for overdentures. Twenty-nine patients received 60 new chairside copings prepared by 3 operators. The copings, used to anchor removable prostheses, were followed up for between 6 months and 4 years with inspection, probing, and radiographic evaluation. Five teeth (8.3%) were extracted. A few clinical problems occurred, including decementation, periodontal pathology (loss of support and bleeding on probing), subgingival decay, and root fracture. No differences were noted in the incidence of complications among the 3 operators. The study demonstrated the clinical predictability of the new copings.

A new coping for overdentures. Part 1: A pilot study of the marginal precision.

The aim of this study was to investigate the marginal precision of new chairside copings prepared on 20 extracted teeth. The marginal fit was examined microscopically through 360-degree external observations. Subsequently, 10 new copings were adapted in vivo on 10 teeth that were planned for extraction. After extraction, the marginal fit was evaluated using the same protocol. The mean values of the marginal gap for the 2 groups (20 and 10 copings) were 24.1 and 32.6 microm, respectively. The marginal precision of the new copings was within the clinically accepted limits.

Absence of soluble CD14 in saliva of young patients with dental caries.

It is generally accepted that salivary components are important for dental health, but to date no clear correlation has been found between one or more of these components and the outcome of dental caries. The identification of salivary factors preventing, favoring or signaling dental caries might help to control the disease. In the present study, western blotting analysis of whole saliva from 20 healthy caries-free children showed the presence of the soluble form of CD14, a bacterial pattern-recognition receptor for many bacterial components that is involved in the innate immune response. The identity of the protein was confirmed through N-terminal sequencing by Edman degradation, and by partial sequencing with mass spectrometry of tryptic peptides. Conversely, CD14 was completely absent in the saliva of 20 age-matched patients affected by two to eight carious lesions, but appeared in their saliva a few weeks after dental restoration. These results suggest that the absence of salivary soluble CD14 could represent an useful index of caries activity, and might be used to detect early carious lesions not visible by oral inspection.

Cytokines and growth factors involved in the osseointegration of oral titanium implants positioned using piezoelectric bone surgery versus a drill technique: a pilot study in minipigs.

BACKGROUND: Most dental implants are positioned using a drilling surgery technique. However, dentistry recently experienced the implementation of piezoelectric surgery. This technique was introduced to overcome some of the limitations involving rotating instruments in bone surgery. This study used biomolecular and histologic analyses to compare the osseointegration of porous implants positioned using traditional drills versus the piezoelectric bone surgery technique. METHODS: Porous titanium implants were inserted into minipig tibias. Histomorphology and levels of bone morphogenetic protein (BMP)-4, transforming growth factor (TGF)-beta2, tumor necrosis factor-alpha, and interleukin-1beta and -10 were evaluated in the peri-implant osseous samples. RESULTS: Histomorphological analyses demonstrated that more inflammatory cells were present in samples from drilled sites. Also, neo-osteogenesis was consistently more active in bone samples from the implant sites that were prepared using piezoelectric bone surgery. Moreover, bone around the implants treated with the piezoelectric bone surgery technique showed an earlier increase in BMP-4 and TGF-beta2 proteins as well as a reduction in proinflammatory cytokines. CONCLUSION: Piezoelectric bone surgery appears to be more efficient in the first phases of bone healing; it induced an earlier increase in BMPs, controlled the inflammatory process better, and stimulated bone remodeling as early as 56 days post-treatment.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.