Klaus Gotfredsen

Evaluation of Guided Bone Generation Around Implants Placed Into Fresh Extraction Sockets: An Experimental Study in Dogs

Immediate placement of implants into fresh extraction sockets would have the principal advantage of decreasing the recommended period of healing. It also would result in a guided placement of the implant, and it could reduce the resorption of the alveolar bone in the extraction area. However, when an implant is placed immediately into an extraction socket, it may not engage the walls of the socket near the crest of the alveolar ridge. With the presence of a bone defect around an implant, ingrowth of soft tissue could compromise the achievement of osseointegration in the crestal bone area. The objective of this study was to evaluate the crestal bone healing response adjacent to implants placed immediately into fresh extraction sockets with and without covering membranes. Eight adult mongrel dogs had the third and fourth mandibular premolars extracted bilaterally. Thirty-two submerged titanium hollow-screw implants were inserted immediately into the extraction sockets. On the right side, the implants were covered with an expanded polytetrafluorethylene membrane, whereas the left side served as a control. One dog was killed after 2 weeks, one after 4 weeks, and six after 12 weeks. Soft tissue dehiscence developed over 10 implants (12-week dogs) covered with membranes. Dehiscence was noted histologically over three contralateral control implants. When soft tissue dehiscence occurred and the membrane was left exposed without oral hygiene during healing, the degree of bone integration was significantly less than in the control sites without membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

A Method for Preparing and Staining Histological Sections Containing Titanium Implants for Light Microscopy

An improved method for preparing and staining ground tissue-implant sections for light microscopy is presented. Undecalcified tissue blocks with titanium implants were dehydrated in an ascending series of ethanol and stained in toto with basic fuchsin. Specimens were infiltrated and embedded in methyl methacrylate and sections were prepared using a cutting-grinding-system. The polished surface was counterstained with light green or anilin blue. Light polymerizing resin was used as slide mounting medium and for mounting the coverglass. The sections obtained were 10-15 microns thick with tissue architecture which clearly differentiated structures at the tissue-implant interface. The method was very useful for computer assisted morphometric analysis.

A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis.

OBJECTIVES The purpose of this clinical study was to describe outcome variables of all-ceramic and metal-ceramic implant-supported, single-tooth restorations. MATERIALS AND METHODS A total of 59 patients (mean age: 27.9 years) with tooth agenesis and treated with 98 implant-supported single-tooth restorations were included in this study. Two patients did not attend baseline examination, but all patients were followed for 3 years. The implants supported 52 zirconia, 21 titanium and 25 gold alloy abutments, which retained 64 all-ceramic and 34 metal-ceramic crowns. At baseline and 3-year follow-up examinations, the biological outcome variables such as survival rate of implants, marginal bone level, modified Plaque Index (mPlI), modified Sulcus Bleeding Index (mBI) and biological complications were registered. The technical outcome variables included abutment and crown survival rate, marginal adaptation of crowns, cement excess and technical complications. The aesthetic outcome was assessed by using the Copenhagen Index Score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. The statistical analyses were mainly performed by using mixed model of ANOVA for quantitative data and PROC NLMIXED for ordinal categorical data. RESULTS The 3-year survival rate was 100% for implants and 97% for abutments and crowns. Significantly more marginal bone loss was registered at gold-alloy compared to zirconia abutments (P = 0.040). The mPlI and mBI were not significantly different at three abutment materials. The frequency of biological complications was higher at restorations with all-ceramic restorations than metal-ceramic crowns. Loss of retention, which was only observed at metal-ceramic crowns, was the most frequent technical complication, and the marginal adaptations of all-ceramic crowns were significantly less optimal than metal-ceramic crowns (P = 0.020). The professional-reported aesthetic outcome demonstrated significantly superior colour match of all-ceramic over metal-ceramic crowns (P = 0.015). However, no significant differences in the other aesthetic parameters at various restoration materials were registered. After 3 years, the patient-reported outcome variables at different restoration materials were not significantly different. CONCLUSION The biological outcomes at the zirconia and metal abutments were comparable. All-ceramic crowns demonstrated better colour match, but higher frequency of marginal discrepancy compared to metal-ceramic crowns. Generally, the patients noticed no difference in aesthetic outcome of all-ceramic and metal-ceramic restorations.

Cobalt release from implants and consumer items and characteristics of cobalt sensitized patients with dermatitis

Background. Cobalt allergy is prevalent in dermatitis patients. Very little documentation exists about current sources of cobalt exposure.

Hyaluronan in non‐surgical and surgical periodontal therapy: a systematic review

AIM To evaluate the effect of hyaluronan (HY) application as monotherapy or as adjunct to non-surgical and/or surgical periodontal therapy. METHODS Literature search was performed according to PRISMA guidelines with the following main eligibility criteria: (a) English or German language; (b) pre-clinical in vivo or human controlled trials; (c) effect size of HY evaluated histologically or clinically. RESULTS Two pre-clinical in vivo studies on surgical treatment and 12 clinical trials on non-surgical and/or surgical treatment were included. Most of the studies were highly heterogeneous, regarding with HY product used and application mode, and of high risk of bias, thus not allowing meta-analysis. The majority of clinical studies described a beneficial, occasionally statistically significant, effect of HY on bleeding on probing (BoP) and pocket depth (PD) reduction (2.28-19.5% and 0.2-0.9 mm, respectively), comparing to controls; no adverse effects were reported. CONCLUSIONS Hyaluronan application as adjunct to non-surgical and surgical periodontal treatment seems to have a beneficial, generally moderate, effect on surrogate outcome variables of periodontal inflammation, i.e., BoP and residual PD, and appears to be safe. The large heterogeneity of included studies, does not allow recommendations on the mode of application or effect size of HY as adjunct to non-surgical and surgical periodontal treatment.

Consensus report ‐ reconstructions on implants. The Third EAO Consensus Conference 2012

INTRODUCTION This group was assigned the task to review the current knowledge in the areas of implant connections to abutments/reconstructions, fixation methods (cement vs. screw retained) for implant-supported reconstructions, as well as the optimal number of implants for fixed dental prosthesis and implant-supported overdentures. MATERIAL AND METHODS The literature was systematically searched and critically reviewed. Four manuscripts were produced in the four subject areas based on systematically search strategy and consensus statements, clinical recommendations and implication for future research were formulated. RESULTS The following four position papers were the basis for the consensus statements, the clinical recommendations and directions for future research: Internal vs. external connections for abutments/reconstructions: A systematic review. Cemented and screw-retained implant reconstructions: A systematic review of the survival and complication rates. What is the optimal number of implants for fixed reconstructions? A systematic review. What is the optimal number of implants for removable reconstructions? A systematic review on implant-supported overdentures. The remit of this working group was to update the existing knowledge in the areas of reconstructions on implants. The group acknowledged the results of previous workshops and systematic reviews were provided by the following position papers: Stefano Gracis, Konstantinos Michalakis, Paolo Vigolo, Per Vult von Steyern, Marcel Zwahlen, Irena Sailer. Internal versus external connections for abutments/reconstructions: a systematic review. Irena Sailer, S. Mühlemann, Marcel Zwahlen, Christoph Hämmerle, Daniel Schneider. Cemented and screw-retained implant reconstructions: A systematic review of the survival and complication rates. Guido Heydecke, Frank Renouard, Ailsa Nicol, Marcel Zwahlen, Tim Joda. What is the optimal number of implants for fixed reconstructions? A systematic review. Mario Roccuzzo, Francesca Bonino, Luigi Gaudioso, Henny Meijer. What is the optimal number of implants for overdentures? A systematic review.

A feasible, aesthetic quality evaluation of implant-supported single crowns: an analysis of validity and reliability

OBJECTIVES To test the reliability and validity of six aesthetic parameters and to compare the professional- and patient-reported aesthetic outcomes. MATERIAL AND METHODS Thirty-four patients with 66 implant-supported premolar crowns were included. Two prosthodontists and 11 dental students evaluated six aesthetic parameters, the Copenhagen Index Score (CIS): (i) crown morphology score, (ii) crown colour match score, (iii) symmetry/harmony score, (iv) mucosal discolouration score, (v) papilla index score, mesially and (vi) papilla index score, distally. The intra- and inter-observer agreement and the internal consistency were analysed by Cohens κ and Cronbachs α, respectively. The validity of CIS parameters was tested against the corresponding Visual Analogue Scales (VAS) scores. The Spearman correlation coefficients were used. Six aesthetic Oral Health Impact Profile (OHIP) questions were correlated to the CIS and the overall VAS scores. RESULTS The intra-observer agreement was >70% in 2/3 and >50% in all observations. The inter-observed agreement was >50% in 4/5 of all observations. The mucosal discolouration score had the overall highest observed agreement followed by the papilla index scores. The crown morphology and the symmetry/harmony scores had the overall lowest agreement. The Cronbach α value was over 0.8 for all observers. All CIS scores demonstrated significant (P<0.0001) correlation to the corresponding VAS scores. Low correlation coefficients (CIS/OHIP: r(s) <0.36; VAS/OHIP: r(s) >-0,24) were found between patient and professional evaluations. CONCLUSIONS The feasibility, reliability and validity of the CIS make the parameters useful for quality control of implant-supported restorations. The professional- and patient-reported aesthetic outcomes had no significant correlation.

Implant supported overdentures--the Copenhagen experience

OBJECTIVES To evaluate the functional and biological effect of implant-supported overdenture treatment in the lower jaw. METHODS AND MATERIALS Thirty-two patients were consecutively treated with Astra Tech implants in the lower jaw for retaining overdentures. All implants had a diameter of 3.5 mm and all but two of the implants were longer than 10 mm. For the implant supported overdentures two methods of attachment were used, a bar or a ball. RESULTS One of 69 fixtures was lost during the 4-5 year observation period. The mean bone loss for all fixtures was less than 0.2 mm per year. Complications included 15 fractures of the ball attachment and 26 episodes of looseness of the matrices holding the screw in place. Patient satisfaction with the treatment of the lower jaw was high although 7 patients found that control of the upper denture was poor following treatment. CONCLUSIONS When the bone quality and quantity is sufficient, two implants can support an overdenture in the lower jaw, providing prosthesis which functions well.

Effect of nanocoating with rhamnogalacturonan-I on surface properties and osteoblasts response.

Long-term stability of titanium implants are dependent on a variety of factors. Nanocoating with organic molecules is one of the methods used to improve osseointegration. Therefore, the aim of this study is to evaluate the in vitro effect of nanocoating with pectic rhamnogalacturonan-I (RG-I) on surface properties and osteoblasts response. Three different RG-Is from apple and lupin pectins were modified and coated on amino-functionalized tissue culture polystyrene plates (aminated TCPS). Surface properties were evaluated by scanning electron microscopy, contact angle measurement, atomic force microscopy, and X-ray photoelectron spectroscopy. The effects of nanocoating on proliferation, matrix formation and mineralization, and expression of genes (real-time PCR) related to osteoblast differentiation and activity were tested using human osteoblast-like SaOS-2 cells. It was shown that RG-I coatings affected the surface properties. All three RG-I induced bone matrix formation and mineralization, which was also supported by the finding that gene expression levels of alkaline phosphatase, osteocalcin, and collagen type-1 were increased in cells cultured on the RG-I coated surface, indicating a more differentiated osteoblastic phenotype. This makes RG-I coating a promising and novel candidate for nanocoatings of implants.

Does longstanding nicotine exposure impair bone healing and osseointegration? An experimental study in rabbits

OBJECTIVES The aim of this study was to analyze the effect of longstanding nicotine exposure on bone healing and osseointegration of titanium implants. MATERIALS AND METHODS 20 female rabbits received either nicotine (n = 10) or saline (n = 10) administered subcutaneously via mini-osmotic pumps for 32 weeks. The pump delivered 6 microg/kg/min of nicotine for the animals in the test group. Blood samples were collected and plasma cotinine levels were measured monthly. Six months after the commencement of nicotine or saline administration three osteotomy preparations, one in right, femoral condyle and two in the right tibia were made. One experimental implant was placed in the femur site and one in the most distal preparation of the tibia. The remaining site in the tibia was left empty. The osteotomy preparation and implant installation procedure was repeated in the left leg of the rabbits after 2 weeks. The implants in the tibial site were subjected to removal torque test (RMT) 2 weeks later. Block biopsies of the two other osteotomy sites were prepared for histological analysis. RESULTS Although no differences in RMT values were found between test and control groups, there was a significant increase in RMT between 2 and 4 weeks within each group. The histomorphometric analysis of bone-to-implant contact and bone density in the bone defects revealed no differences between the test and the control group after 2 or 4 weeks of healing. CONCLUSION Longstanding (6 months) nicotine exposure did not impair bone healing and osseointegration of titanium implants.