Oral Implants: The Paradigm Shift in Restorative Dentistry.

The discovery of the phenomenon "osseointegration," or functional ankylosis, has led to the development of oral implants with high clinical performance. Consequently, the placement of titanium implants has changed the paradigms of restorative dentistry. Implants are used to prevent placing reconstructions anchored on natural teeth when these are vital and intact. Furthermore, implants are suitable to improve subjective chewing function and to replace missing and strategically important abutments. The osseointegration process is characterized by a predictable sequence of healing events that encompass the formation of woven bone, parallel fibers, and lamellar bone and result in fully functional bone that will remodel throughout life. While the osseointegration facilitates the use of implants as prosthetic abutments, it has to be kept in mind that the peri-implant soft tissue may be subject to biological complications. This, in turn, may result in an infectious process that will jeopardize the osseointegration. Consequently, the monitoring of the peri-implant tissues is an important aspect, and early intervention in situations with peri-implant mucositis is mandatory for the prevention of peri-implantitis. Hence, it is evident that oral implants need lifelong maintenance care if their longevity is to be assured.

Immediate and delayed loading of fixed dental prostheses supported by single or two splinted implants: A histomorphometric study in dogs.

To evaluate presumptive differences in osseointegration at implants supporting crowns that are physiologically loaded either immediately or 3 months after installation. All premolars and first molars were extracted bilaterally in six dogs. After 3 months of healing, three implants were installed on the premolar region and two in the molar region in one side of the mandible. Likewise, after another 3 months, five implants were installed in the contralateral side, and impressions were taken bilaterally. Within 48 hours, two single crowns were screwed bilaterally onto two implants in the premolar region, and two splinted crowns reproducing the shape of the first molar were screwed bilaterally onto the implants in the molar region. The mesial implants were used as no-loaded controls. Sacrifices were performed after 3 months, and histological analyses were performed. At the premolar sites, mineralised bone-to-implant contact (MBIC%) was 78.0 ± 4.0% and 70.9 ± 7.9% at the delayed and immediately loaded sites, respectively. This difference was statistically significant. At the control implants, MBIC% was 61.4 ± 14.7% and 63.1 ± 13.1% at the delayed and the immediately loaded sites, respectively. At the molar sites, MBIC% was 79.2 ± 10.9% and 61.1 ± 10.3% at the delayed and immediately loaded sites, respectively. Applying a delayed loading to fixed dental prostheses supported by single or two splinted implants yielded higher proportions of bone-to-implant contact (osseointegration) compared to immediately loaded implants. Moreover, both types of loading protocols yielded a higher rate of osseointegration compared to unloaded implant sites after 3 months following implant installation.

Strontium hydroxyapatite in situ gel-forming system - a new approach for minimally invasive bone augmentation.

OBJECTIVES: To achieve ideal functional and aesthetic requirements, ridge augmentation is often required before dental implant placement. Bone augmentation (especially vertical), which normally consists of complex and invasive surgeries, still remains challenge. This study seeks to investigate the feasibility of an injectable in situ gel-forming system containing strontium hydroxyapatite (SrHA) and alginate for minimally invasive bone augmentation in a rat calvarial model. MATERIAL AND METHODS: SrHA-alginate solution was prepared by mixing SrHA powder with alginate solution (20 mg/mL) to the final concentration of 0.5% (w/v). Each animal received a 200-µL single subperiosteal injection of either SrHA-alginate solution or alginate solution. The new bone formation was assessed at 0, 4, and 8 weeks histologically and radiologically. RESULTS: The SrHA-alginate solution materials could form solid gel once injected. As such, no sutures were required to close the injection site. Significantly greater amount of new bone formation was observed in the SrHA-alginate group compared with the alginate group both by micro-CT and by histological section. The newly formed bone in the SrHA-alginate group originated both from the underlying original bone and from the elevated periosteum. A 2.3-fold increase of the vertical bone height was observed in the SrHA-alginate group compared with 1.3-fold increase in the alginate group. CONCLUSIONS: Rat calvarial bone augmentation was achieved by a single subperiosteal injection of SrHA-alginate solution without any administration of stem cells or growth factors. The in situ gel-forming material may hold potential therapeutic benefits for local bone augmentation in a minimally invasive manner.

Novel bioresorbable strontium hydroxyapatite membrane for guided bone regeneration.

OBJECTIVES: Membrane materials have been widely used for guided bone regeneration (GBR). However, due to bio-functional limitation of the current membranes, the ideal resorbable membrane that can stimulate bone regeneration has yet to be developed. This study seeks to investigate the effects of a strontium hydroxyapatite (SrHA)-containing membrane for GBR. MATERIAL AND METHODS: Strontium hydroxyapatite powder was synthesized and mixed with gelatin solution to the final concentration of 10 mg/ml (Sr10) and 20 mg/ml (Sr20). Approximately 100-µm-thick membranes were fabricated, and the mechanical properties and strontium ion release pattern were analyzed. Rat bone marrow stromal cell (BMSC) responses were investigated in vitro. Bilaterial rat calvarial defects were used in vivo to compare the SrHA membranes against commercially available collagen membranes and evaluated radiologically and histologically. RESULTS: Strontium hydroxyapatite membranes exhibited higher elasticity and strength than the collagen membrane, and slow strontium ion release was also confirmed. No BMSC cytotoxicity was found on the SrHA membranes, and the alkaline phosphatase positively stained area was significantly greater than the collagen membrane at earlier time point. At 4 weeks, both micro-CT and histological analyses revealed that the Sr20 group yielded significantly greater bone formation. CONCLUSIONS: The SrHA-containing membrane developed in this study was found to be a biocompatible material that can stimulate BMSC differentiation as well as bone regeneration and maturation in rat calvarial defects at early time point compared with collagen membrane. The best result was observed in Sr20 group, which can be potentially effective for GBR.

Effects of root surface debridement using Er:YAG laser versus ultrasonic scaling - a SEM study.

OBJECTIVE: Despite promising results of Er:YAG laser in periodontal debridement, to date there is no consensus about the ideal settings for clinical use. This experimental clinical trial aimed to determine the effects of debridement using Er:YAG laser and to compare with ultrasonic treatment. MATERIALS AND METHODS: Sixty-four teeth were divided into two in vivo and in vitro subgroups. Each tooth received ultrasonic treatment on one side and Er:YAG laser debridement at either 60, 100, 160 or 250 mJ pulse(-1) and at 10 Hz on the other side on a random basis. All samples were morphologically analyzed afterwards under scanning electron microscope for surface changes and dentinal tubules exposure. Treatment duration (d) was also recorded. RESULTS: Laser debridement produced an irregular, rough and flaky surface free of carbonization or meltdown while ultrasound produced a relatively smoother surface. The number of exposed dentinal tubules (n) followed an energy-dependent trend. The number of exposed tubules among the in vivo laser groups was n 60 mJ = n 100 mJ < n 160 mJ < n 250 mJ (P < 0.001). Also 160 and 250 mJ lasers led to significantly more dentinal exposure than ultrasound under in vivo condition. Within the in vitro laser groups, dentinal tubules exposure was n 60 mJ < n 100 mJ < n 160 mJ < n 250 mJ (P ≤ 0.0015). Furthermore, in vitro laser treatments at 100, 160 and 250 mJ led to significantly more dentinal denudation than ultrasound. Treatment duration (d) for the in vivo groups was d 60 mJ > d 100 mJ > d Ultrasound = d 160 mJ > d 250 mJ (P ≤ 0.046), while for the in vitro groups it was d 60 mJ > d 100 mJ = d Ultrasound = d 160 mJ >d 250 mJ (P ≤ 0.046). CONCLUSIONS: Due to excessive treatment duration and surface damage, Er:YAG laser debridement at 60 and 250 mJ pulse(-1), respectively, is not appropriate for clinical use. Although laser debridement at 100 and 160 mJ pulse(-1) seems more suitable for clinical application, compared to ultrasound the former is more time-consuming and the latter is more aggressive. Using a feedback device or lower pulse energies are recommended when using laser in closed field.

Developing implant dentistry education in Europe: the continuum from undergraduate to postgraduate education and continuing professional development.

INTRODUCTION: Implant dentistry is a treatment modality which has mainstream clinical practice of comprehensive care, which however is not adequately represented in the undergraduate dental curricula. A consensus workshop organised by ADEE in 2008, set the benchmarks for the knowledge and competences a modern dental practitioner must possess with regard to implant dentistry, as well as defined undergraduate and postgraduate pathways for the acquisition of these competences. Today, 5 years later, there exist several challenges for the implementation of these benchmarks in both undergraduate curricula but also post-graduation educational pathways. METHODS: A consensus workshop was organised by ADEE, bringing together 48 opinion leaders, including academic teachers of all disciplines related to implant dentistry, specialists, representatives of relevant scientific and professional associations, as well as industry delegates. The objectives of the workshop were to evaluate the existing scientific literature, reported experience and best practices in order to identify potential and limitations for the implementation of implant dentistry in the undergraduate curriculum, as well produce recommendations for the optimal educational structures for postgraduate programmes and continuing professional development. RESULTS: The scientific committee conducted two European-wide questionnaire surveys to better document the current state of education in implant dentistry. Upon completion of the surveys, reviewers were appointed to produce three scientific review papers, identifying current achievements and future challenges. Finally, during the 3 days of the workshop, all the evidence was reviewed and the main conclusions and recommendations that were adopted by all participants are reported in the present Consensus Paper. CONCLUSIONS: Implementation of implant dentistry in the undergraduate curriculum has improved significantly, but still lags behind the benchmarks set in 2008 and the diversity between institutions remains big. At the post-graduation level, there is currently a wide diversity of courses and pathways towards competences related to implant dentistry and there is at present a great need for quality assurance, as well as standardisation and transparency of the learning outcomes.

Anti-infective surgical therapy of peri-implantitis. A 12-month prospective clinical study.

AIM: The aim of this prospective cohort study was to evaluate an anti-infective surgical protocol for the treatment of peri-implantitis. MATERIALS AND METHODS: Thirty-six implants in 24 partially dentate patients with moderate to advanced peri-implantitis were treated using an anti-infective surgical protocol incorporating open flap debridement and implant surface decontamination, with adjunctive systemic amoxicillin and metronidazole. Treatment outcomes were assessed at 3, 6 and 12 months. Patient-based statistical analyses using multiple regression analyses were performed. RESULTS: There was 100% survival of treated implants at 12 months. At 3 months, there were statistically significant (P < 0.01) reductions in mean probing depths (PD), Bleeding on Probing (BoP) and suppuration. The greater the mean PD at baseline, the greater the PD reduction at 3 months. At 3 months, there was also a significant mean facial mucosal recession of 1 mm (P < 0.001). All these changes were maintained at 6 and 12 months. At 12 months, all treated implants had a mean PD < 5 mm, while 47% of the implants had complete resolution of inflammation (BoP negative). At 12 months, 92% of implants had stable crestal bone levels or bone gain. There were no significant effects of smoking on any of the treatment outcomes. CONCLUSIONS: For the treatment of peri-implantitis, an anti-infective protocol incorporating surgical access, implant surface decontamination and systemic antimicrobials followed by a strict postoperative protocol was effective at 3 months with the results maintained for up to 12 months after treatment.

Transcriptional profiling of osseointegration in humans.

OBJECTIVE: To determine the temporal gene expression profile associated with the early healing events during osseointegration in a human model. MATERIAL AND METHODS: Nine solid screw-type cylindrical titanium implants, 4 mm long and 2.8 mm wide, with a chemically modified surface (SLActive) were surgically inserted in the retromolar area of nine human volunteers. The devices were removed using a trephine following 4, 7 and 14 days of healing. The tissue surrounding the implant was harvested, total RNA was extracted and microarray analysis was carried out to identify the differences in the transcriptome between days 4, 7 and 14. RESULTS: Gene ontology (GO) analysis of the temporal transcriptional changes was characteristic of a maturing, osteogenic process over the course of the study (4-14 days). At day 4, a gene expression profile associated with proliferation and immuno-inflammatory processes was predominant. However, by day 14, by far the most predominant mechanisms were associated with skeletogenesis, with the GO categories of skeletal system development, bone development and ossification being predominant, with the majority of changes occurring between days 7 and 14. Furthermore, the biological processes of angiogenesis and neurogenesis were also predominant by day 14. In terms of signal transduction, I-κB kinase/NF-κB cascade was predominant at day 4, whereas TGF-ß/BMP, Wnt and Notch signalling were all associated with the osteogenic process over the duration of the study. Furthermore, Ras and Rho protein signal transduction was regulated throughout the osseointegration process. CONCLUSION: The temporal transcriptional changes during osseointegration involve the expression of proliferation and immuno-inflammatory response associated genes during the early stages of osseointegration, which are ultimately replaced by genes associated with the biological processes of skeletogenesis, angiogenesis and neurogenesis. The early immuno-inflammatory changes appear to be regulated via the I-κB kinase/NF-κB cascade, whereas the later osteogenesis-related mechanisms are regulated by TGF-ß/BMP, Notch and Wnt signaling.

Gene expression profile of osseointegration of a hydrophilic compared with a hydrophobic microrough implant surface.

OBJECTIVES: To compare the gene expression profile of osseointegration associated with a moderately rough and a chemically modified hydrophilic moderately rough surface in a human model. MATERIAL AND METHODS: Eighteen solid screw-type cylindrical titanium implants, 4 mm long and 2.8 mm wide, with either a moderately rough (SLA) or a chemically modified moderately rough (SLActive) surface were surgically inserted in the retromolar area of nine human volunteers. The devices were removed using a trephine following 4, 7 and 14 days of healing. The tissue surrounding the implant was harvested, total RNA was extracted and microarray analysis was carried out to identify the differences in the transcriptome between the SLA and SLActive surfaces at days 4, 7 and 14. RESULTS: There were no functionally relevant gene ontology categories that were over-represented in the list of genes that were differentially expressed at day 4. However, by day 7, osteogenesis- and angiogenesis-associated gene expression were up-regulated on the SLActive surface. Osteogenesis and angiogenesis appeared to be regulated by BMP and VEGF signalling, respectively. By day 14, VEGF signalling remains up-regulated on the SLActive surface, while BMP signalling was up-regulated on the SLA surface in what appeared to be a delayed compensatory response. Furthermore, neurogenesis was a prominent biological process within the list of differentially expressed genes, and it was influenced by both surfaces. CONCLUSIONS: Compared with SLA, SLActive exerts a pro-osteogenic and pro-angiogenic influence on gene expression at day 7 following implant insertion, which may be responsible for the superior osseointegrative properties of this surface.

Global oral health inequalities: task group--periodontal disease.

Periodontal diseases constitute one of the major global oral health burdens, and periodontitis remains a major cause of tooth loss in adults worldwide. The World Health Organization recently reported that severe periodontitis exists in 5-20% of adult populations, and most children and adolescents exhibit signs of gingivitis. Likely reasons to account for these prevalent diseases include genetic, epigenetic, and environmental risk factors, as well as individual and socio-economic determinants. Currently, there are fundamental gaps in knowledge of such fundamental issues as the mechanisms of initiation and progression of periodontal diseases, which are undefined; inability to identify high-risk forms of gingivitis that progress to periodontitis; lack of evidence on how to prevent the diseases effectively; inability to detect disease activity and predict treatment efficacy; and limited information on the effects of integration of periodontal health as a part of the health care program designed to promote general health and prevent chronic diseases. In the present report, 12 basic, translational, and applied research areas have been proposed to address the issue of global periodontal health inequality. We believe that the oral health burden caused by periodontal diseases could be relieved significantly in the near future through an effective global collaboration.

Role of flap tension in primary wound closure of mucoperiosteal flaps: a prospective cohort study.

AIM: To evaluate the role of suture tension in primary wound closure of mucoperiosteal flaps. MATERIALS AND METHODS: Sixty patients, scheduled for a single implant installation, were recruited. Before suturing, the wound closing forces were measured with an electronic tension device. One week after the surgery, the wounds were inspected with regard to complete closure. RESULTS: The applied tension varied between 0.01 and 0.4 N. In 72% a tension of 0.01-0.1 N was applied, resulting in few dehiscences (10%). Higher closing forces (>0.1 N) increased the percentage of wound dehiscences significantly (> or = 40%). CONCLUSIONS: It appears necessary to control flap tension at the time of wound closure to achieve a primary closure.

Significance of Periodontal Risk Assessment in the recurrence of periodontitis and tooth loss.

AIM: To investigate the association of the Periodontal Risk Assessment (PRA) model categories with periodontitis recurrence and tooth loss during supportive periodontal therapy (SPT) and to explore the role of patient compliance. MATERIAL AND METHODS: In a retrospective cohort, PRA was performed for 160 patients after active periodontal therapy (APT) and after 9.5 +/- 4.5 years of SPT. The recurrence of periodontitis and tooth loss were analysed according to the patient's risk profile (low, moderate or high) after APT and compliance with SPT. The association of risk factors with tooth loss and recurrence of periodontitis was investigated using logistic regression analysis. RESULTS: In 18.2% of patients with a low-risk profile, in 42.2% of patients with a moderate-risk profile and in 49.2% of patients with a high-risk profile after APT, periodontitis recurred. During SPT, 1.61 +/- 2.8 teeth/patient were lost. High-risk profile patients lost significantly more teeth (2.59 +/- 3.9) than patients with moderate- (1.02 +/- 1.8) or low-risk profiles (1.18 +/- 1.9) (Kruskal-Wallis test, p=0.0229). Patients with erratic compliance lost significantly (Kruskal-Wallis test, p=0.0067) more teeth (3.11 +/- 4.5) than patients compliant with SPT (1.07 +/- 1.6). CONCLUSIONS: In multivariate logistic regression analysis, a high-risk patient profile according to the PRA model at the end of APT was associated with recurrence of periodontitis. Another significant factor for recurrence of periodontitis was an SPT duration of more than 10 years.

Dimensional ridge alterations following immediate implant placement in molar extraction sites: a six-month prospective cohort study with surgical re-entry.

AIM: To assess dimensional ridge alterations following immediate implant placement in molar extraction sites. MATERIAL AND METHODS: Twelve subjects received 12 immediate transmucosal implants in molar extraction sites. Peri-implant defects were treated according to the principles of Guided Bone Regeneration by means of a deproteinized bone substitute and a bioresorbable collagen membrane. Changes in vertical (IS-BD, CREST-BD) and horizontal distances (EC-I, IC-I) of alveolar bony walls to the bottom of the defects (BD) and to the implant surfaces (I) were compared between implant placement and surgical re-entry at 6 months. RESULTS: The implant survival rate at 6 months was 100%. Statistically significant differences (P<0.01) were observed in the mean changes in vertical distances IS-BD and CREST-BD between baseline and re-entry. At re-entry, all peri-implant marginal defects assessed from the internal socket wall to the implant surface (IC-I) were healed. The residual combined thickness of the buccal wall with the newly formed peri-implant bone at sites with an initial thickness of 1 mm was statistically significantly smaller (P<0.05) compared with that of sites with an initial buccal thickness of 2 mm (2.50 +/- 0.76 vs. 4+/-0 mm). CONCLUSIONS: The marginal defects around immediate implants placed in molar extraction sites were completely filled after 6 months of healing through de novo bone formation. Bone resorption was observed from the external aspects of the buccal and oral socket walls. Dimensional changes of the external socket walls were mostly pronounced at the buccal aspects.

Soft tissues healing at immediate transmucosal implants placed into molar extraction sites with buccal self-contained dehiscences. A 12-month controlled clinical trial.

AIM: To assess soft tissues healing at immediate transmucosal implants placed into molar extraction sites with buccal self-contained dehiscences. MATERIAL AND METHODS: For this 12-month controlled clinical trial, 15 subjects received immediate transmucosal tapered-effect (TE) implants placed in molar extraction sockets displaying a buccal bone dehiscence (test sites) with a height and a width of > or =3 mm, respectively. Peri-implant marginal defects were treated according to the principles of Guided Bone Regeneration (GBR) by means of deproteinized bovine bone mineral particles in conjunction with a bioresorbable collagen membrane. Fifteen subjects received implants in healed molar sites (control sites) with intact buccal alveolar walls following tooth extraction. In total, 30 TE implants with an endosseous diameter of 4.8 mm and a shoulder diameter of 6.5 mm were used. Flaps were repositioned and sutured, allowing non-submerged, transmucosal soft tissues healing. At the 12-month follow-up, pocket probing depths (PPD) and clinical attachment levels (CAL) were compared between implants placed in the test and the control sites, respectively. RESULTS: All subjects completed the 12-month follow-up period. All implants healed uneventfully, yielding a survival rate of 100%. After 12 months, statistically significantly higher (P<0.05) PPD and CAL values were recorded around implants placed in the test sites compared with those placed in the control sites. CONCLUSIONS: The findings of this controlled clinical trial showed that healing following immediate transmucosal implant installation in molar extraction sites with wide and shallow buccal dehiscences yielded less favorable outcomes compared with those of implants placed in healed sites, and resulted in lack of 'complete' osseointegration.

A survey on undergraduate implant dentistry education in Europe.

INTRODUCTION: The aim of the survey was to assess the status of implant dentistry education and addressed various aspects related to competence level, practical implementation and barriers for further development in the field. MATERIALS AND METHODS: An e-mail survey was performed amongst 73 opinion leaders from 18 European countries invited to the Association for Dental Education in Europe (ADEE) workshop on implant dentistry. RESULTS: Forty-nine surveys were returned (67%) and it was found that theoretical and pre-clinical courses to an average of 36 h are given to undergraduates; 70% reported that students assist or treat patients with prosthetics; 53% reported that students assist with surgery and only 5% is operating patients. In 23% of the schools optional undergraduate courses are available and 90% offer postgraduate training. Barriers for including prosthetics and surgery are lack of time, funding or staff. Partial restorations, including surgery, in the posterior regions may be provided by dentists after attendance at additional courses but complex treatments should be limited to specialists. CONCLUSION: This survey confirms that implant dentistry is part of the undergraduate curriculum, albeit with a disparity in time. Whereas implant dentistry is an important part of clinical practice, coverage in the curriculum is limited and when compared with 10 years ago, even stagnating. Priorities within the curriculum should be evaluated depending on demands and treatment needs of the population. To optimise education, learning guidelines should be developed, based on the expected competencies for practicing dentists. Undergraduate education may start the process that must continue through all levels of education, including the postgraduate level.

Teaching and assessment of implant dentistry in undergraduate and postgraduate education: a European consensus.

This paper constitutes a summary of the consensus documents agreed at the First European Workshop on Implant Dentistry University Education held in Prague on 19-22 June 2008. Implant dentistry is becoming increasingly important treatment alternative for the restoration of missing teeth, as patients expectations and demands increase. Furthermore, implant related complications such as peri-implantitis are presenting more frequently in the dental surgery. This consensus paper recommends that implant dentistry should be an integral part of the undergraduate curriculum. Whilst few schools will achieve student competence in the surgical placement of implants this should not preclude the inclusion of the fundamental principles of implant dentistry in the undergraduate curriculum such as the evidence base for their use, indications and contraindications and treatment of the complications that may arise. The consensus paper sets out the rationale for the introduction of implant dentistry in the dental curriculum and the knowledge base for an undergraduate programme in the subject. It lists the competencies that might be sought without expectations of surgical placement of implants at this stage and the assessment methods that might be employed. The paper also addresses the competencies and educational pathways for postgraduate education in implant dentistry.

The rationale for the introduction of implant dentistry into the dental curriculum.

This paper provides arguments for the introduction of implant dentistry into the undergraduate curriculum. The survival of teeth is very high when disease is diagnosed and treated properly and maintenance is taken care of. Nevertheless, tooth replacements by fixed and removable prostheses are highly prevalent. It is expected that dentists will face a dramatically increased need to care for elderly patients and partially edentulous patients. Hence, the demand for implant reconstructions will be substantial and more appropriately trained and competent health professionals will be needed. Increasing demands of the patient regarding aesthetics and function will influence the demands for implant therapy. The improvement of oral function and subjective chewing comfort, the preservation of tooth structures or existing reconstructions and the replacement of missing, strategically important teeth are major indications for implant placement. From both a biological and an economical point of view, the single tooth replacement with an implant is the first choice in situations with no or minimally restored neighbouring teeth compared with conventional bridgework. Stability of full dentures represent a major problem especially for the mandible. It is well documented that placement of two implants supporting an overdenture substantially improve chewing capacity, increase quality of life and is a simple and cost-effective treatment thus rendering such treatment a 'standard of care' procedure. There is no doubt that dental students should learn to incorporate the indication of oral implants in their overall treatment planning. Therefore, they will have to understand the basic aspects of healing and tissue integration, basic biomechanical and material science principles as well as surgical and prosthetic techniques. They will have to be able to monitor continuously the peri-implant tissues, render appropriate supportive therapy and cope with biological and technical complications. While it is evident that the surgical procedure per se may require additional competence, the remainder of the aspects mentioned should be taught in the dental curriculum. This should include the attribution of responsibility for maintenance of implants and handling of biological and technical complications. Moreover, it is desirable to include the surgical technique for implant placement for 'straightforward' cases into the dental curriculum. The levels and limitations to which the various aspects of implant dentistry and related skills are to be taught are determined by the academic community. Obviously, ethical and legal aspects of implant dentistry should not be forgotten.

Bleeding on probing and pocket probing depth in relation to probing pressure and mucosal health around oral implants.

OBJECTIVES: To assess the bleeding on probing (BOP) tendency and periodontal probe penetration when applying various probing forces at implant sites in patients with a high standard of oral hygiene with well-maintained peri-implant tissues. MATERIAL AND METHODS: Seventeen healthy patients with excellent oral hygiene in a maintenance program after having been treated for periodontitis or gingivitis were recruited. Missing teeth had been replaced using oral implants. The BOP and probing depth (PPD) were assessed at the mid-buccal, mid-oral, mesial and distal aspects of the buccal surfaces of each implant. Moreover, contralateral teeth were designated and assessed for BOP and PPD in the same locations and at the same observation visits. At each visit, implants and contralateral teeth were randomly assigned to one of the standardized probing forces (0.15 or 0.25 N). The second probing force was applied at the repetition of the examination 7 days later. RESULTS: Increasing the probing pressure by 0.1 N from 0.15 N resulted in an increase of BOP percentage by 13.7% and 6.6% for implants and contralateral teeth, respectively. There appeared to be a significant difference of the mean BOP percentage at implant and tooth sites when a probing pressure of 0.25 N was applied. A significantly deeper mean PPD at implant sites compared with tooth sites was found irrespective of the probing pressure applied. CONCLUSIONS: The results of the present study demonstrated that 0.15 N might represent the threshold pressure to be applied to avoid false positive BOP readings around oral implants. Hence, probing around implants demonstrated a higher sensitivity compared with probing around teeth.

Marginal fit of cemented and screw-retained crowns incorporated on the Straumann (ITI) Dental Implant System: an in vitro study.

AIM: The aim of this study was to assess the marginal fit of crowns on the Straumann (ITI) Dental Implant System with special consideration of different casting dental materials. MATERIAL AND METHODS: Sixty porcelain-fused-to-metal crowns were fabricated: 18 crowns on standard cone abutments with an impression cylinder, partially prefabricated analogs, no coping and screw-retained (A); 18 crowns on solid abutments without an impression device, no analogs, no coping and cemented (B); and 18 crowns on solid abutments using an impression transfer cap, an analog with a shoulder, no coping and cemented (C). In each group, six crowns were made on epoxy mastercasts (Bluestar), six on synthetic plaster (Moldasynt) and six on super hard stone (Fujirock). Six additional crowns were fabricated with the transversal screw retention system onto the Octa system with impression transfer caps, metal analogs, gold copings and screw-retained (D). Impregum was used as impression material. Crowns of B and C were cemented with KetacCem. Crowns of A and D were fixed with an occlusal screw torqued at 15 N cm. Crowns were embedded, cut and polished. Under a light microscope using a magnification of x 100, the distance between the crown margin (CM) and the shoulder (marginal gap, MG) and the distance between the CM and the end of the shoulder (crown length, CL) was measured. RESULTS: MGs were 15.4+/-13.2 microm (A), 21.2+/-23.1 microm (B), 11+/-12.1 microm (C) and 10.4+/-9.3 microm (D). No statistically significantly differences using either of the casting materials were observed. CLs were -21.3+/-24.8 microm (A), 3+/-28.9 microm (B), 0.5+/-22 microm (C) and 0.1+/-15.8 microm (D). Crowns were shorter on synthetic casting materials compared with stone casts (P<0.005). CONCLUSIONS: CMs fit precisely with both cemented and screw-retained versions as well as when using no, partial or full analogs.