Henny J. A. Meijer

Treatment outcome of immediate, early and conventional single-tooth implants in the aesthetic zone: a systematic review to survival, bone level, soft-tissue, aesthetics and patient satisfaction

AIM This study evaluated, through a systematic review of the literature, the outcome of single-implant restorations in the aesthetic zone with natural adjacent teeth, thereby addressing immediate, early and conventional implant approaches. MATERIAL AND METHODS MEDLINE (1950-2008), EMBASE (1966-2008), and CENTRAL (1800-2008) were searched to identify eligible studies. Two reviewers independently assessed the methodological quality using specific study-design-related assessment forms. RESULTS Out of 86 primarily selected articles, 19 studies fulfilled the inclusion criteria. A meta-analysis showed an overall survival rate of 95.5% [95% confidence interval: (93.0-97.1)] after 1 year. A stratified meta-analysis revealed no differences in survival between immediate, early and conventional implant strategies. Little marginal peri-implant bone resorption was found together with low incidence of biological and technical complications. No significant differences in outcome measures were reported in clinical trials comparing immediate, early or conventional implant strategies. CONCLUSION The included literature suggested that promising short-term results could be achieved for immediate, early and conventional single-implants in the aesthetic zone. However, important parameters as aesthetic outcome, soft-tissue aspects, and patient satisfaction were clearly underexposed. The question whether immediate and early single-implant therapies would result in better treatment outcomes remained inconclusive due to lack of well-designed controlled clinical studies.

Isolation of a cytomegalovirus-like agent from wild rats

SummaryIn 8 of 10 wild rats trapped in The Netherlands, an infectious viruslike agent was isolated predominantly from the salivary glands and could be serially passed in laboratory rats. In rat embryo cells a typical cytomegalo-like cytopathic effect was produced. The morphologic and cultural characteristics of the isolated agent were comparable with those of the mouse cytomegalovirus (MCMV). The virus-nucleocapsid had a size of 92 nm and was not ether-resistant. The extracellular nucleocapsids were often enclosed by an outer layer of very variable shape and size. The formation of Fc receptors on cells infected with the rat virus could be demonstrated. The wild rats possessed neutralizing antibodies to the isolated agent. The rat agent grew only in rat embryo fibroblast cells while MCMV grew in rat and mouse embryo cells. The rat agent gave plaques in REF monolayers. Electron microscope studies showed the presence of nucleocapsids in the nucleus.

A systematic review of the prognosis of short (<10 mm) dental implants placed in the partially edentulous patient

AIM This study evaluated, through a systematic review of the literature, the estimated implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. MATERIALS AND METHODS A systematic search was conducted in the electronic databases of MEDLINE (1980-October 2009) and EMBASE (1980-October 2009) to identify eligible studies. Two reviewers independently assessed the methodological quality of the articles using specific study design-related quality assessment forms. RESULTS Twenty-nine methodologically acceptable studies were selected. A total of 2611 short implants (lengths 5-9.5 mm) were analysed. An increase in implant length was associated with an increase in implant survival (from 93.1% to 98.6%). Heterogeneity between studies was explored by subgroup analyses. The cumulative estimated failure rate of studies performed in the maxilla was 0.010 implants/year, compared with 0.003 found in the studies in the mandible. For studies that also included smokers, the failure rate was 0.008 compared with 0.004 found in studies that excluded smokers. Surface topography and augmentation procedure were not sources of heterogeneity. CONCLUSION There is fair evidence that short (<10 mm) implants can be placed successfully in the partially edentulous patient, although with a tendency towards an increasing survival rate per implant length, and the prognosis may be better in the mandible of non smoking patients.

Biology of Rat Cytomegalovirus Infection

Cytomegalovirus infection of Brown Norway rats was studied after intraperitoneal or subcutaneous inoculation of virus. No clinical illness was apparent during the 1st month postinfection (p.i.). Low titers of virus were detected in many organs at day 4 p.i. for the intraperitoneally inoculated animals and at day 11 p.i. for those inoculated subcutaneously. Thereafter, the virus disappeared from all tested organs except the salivary glands, where it appeared on day 11 p.i. and reached high levels by 4 weeks p.i. Histologically, no abnormalities were observed. The virus had an immunosuppressive effect during the 1st week p.i., as indicated by the immune response to sheep red blood cells.

Mandibular overdentures supported by two or four endosseous implants: a 10-year clinical trial

OBJECTIVE The aim of this 10-year clinical trial was to evaluate the treatment outcome (condition of hard and soft peri-implant tissues, patient satisfaction, surgical and prosthetic aftercare) of mandibular overdentures supported by two or four implants. MATERIALS AND METHODS Sixty edentulous patients with a mandibular height between 12 and 18 mm participated. Thirty patients were treated with an overdenture supported by two IMZ implants (group A) and 30 patients were treated with an overdenture supported by four IMZ implants (group B). Standardised clinical and radiographic parameters were evaluated 6 weeks after completion of the prosthetic treatment and after 1, 5 and 10 years of functional loading. Prosthetic and surgical aftercare was scored during the evaluation period, as well as patient satisfaction. RESULTS There were no statistically significant differences with regard to any of the studied clinical or radiographic parameters of the peri-implant tissues between the groups. In addition, no differences in satisfaction and aftercare were observed between the groups. CONCLUSION There is no difference in the clinical and radiographical state of patients treated with an overdenture on two or four implants during a 10-year evaluation period. Patients of both groups were evenly satisfied with their overdentures and received the same amount of aftercare. For reasons of cost-effectiveness, a two-implant overdenture is advised for patients with a Cawood classes IV-VI resorption of the mandible and complaints concerning retention and stability of the lower denture.

A systematic review of implant-supported maxillary overdentures after a mean observation period of at least 1 year

AIM The aim of the present systematic review of implant-supported maxillary overdentures was to assess the survival of implants, survival of maxillary overdentures and the condition of surrounding hard and soft tissues after a mean observation period of at least 1 year. MATERIAL AND METHODS MEDLINE (1950-August 2009), EMBASE (1966-August 2009) and CENTRAL (1800-August 2009) were searched to identify eligible studies. Two reviewers independently assessed the articles. RESULTS Out of 147 primarily selected articles, 31 studies fulfilled the inclusion criteria. A meta-analysis showed an implant survival rate (SR) of 98.2% per year in case of six implants and a bar anchorage. In case of four implants and a bar anchorage, the implant SR was 96.3% per person. In case of four implants and a ball anchorage, the implant SR was 95.2% per year. CONCLUSION In all three treatment options, the SR of the implants is more than 95%. The studies included reveal that a maxillary overdenture supported by six dental implants, which are connected with a bar, is the most successful treatment regarding survival of both the implants and overdenture. Second in line is the treatment option with four implants and a bar. The treatment option with four or less implants and a ball attachment system is the least successful.

A Double‐Blind Randomized Controlled Trial (RCT) of Titanium‐13Zirconium versus Titanium Grade IV Small‐Diameter Bone Level Implants in Edentulous Mandibles – Results from a 1‐Year Observation Period

BACKGROUND The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two-implant overdenture has been recommended as the standard of care. The use of small-diameter implants may extend treatment options and reduce the necessity for bone augmentation. However, the mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable. PURPOSE This randomized, controlled, double-blind, multicenter study investigated in a split-mouth model whether small-diameter implants made from Titanium-13Zirconium alloy (TiZr, Roxolid™) perform at least as well as Titanium Grade IV implants. METHODS AND MATERIALS Patients with an edentulous mandible received one TiZr and one Ti Grade IV small-diameter bone level implant (3.3 mm, SLActive®) in the interforaminal region. The site distribution was randomized and double-blinded. Outcome measures included change in radiological peri-implant bone level from surgery to 12 months post-insertion (primary), implant survival, success, soft tissue conditions, and safety (secondary). RESULTS Of 91 treated patients, 87 were available for the 12-month follow-up. Peri-implant bone level change (-0.3 ± 0.5 mm vs -0.3 ± 0.6 mm), plaque, and sulcus bleeding indices were not significantly different between TiZr and Ti Grade IV implants. Implant survival rates were 98.9 percent and 97.8 percent, success rates were 96.6 percent and 94.4 percent, respectively. Nineteen minor and no serious adverse events were related to the study devices. CONCLUSION This study confirms that TiZr small-diameter bone level implants provide at least the same outcomes after 12 months as Ti Grade IV bone level implants. The improved mechanical properties of TiZr implants may extend implant therapy to more challenging clinical situations.

Mandibular overdentures supported by two Branemark, IMZ or ITI implants: a ten-year prospective randomized study

OBJECTIVES The aim of this prospective comparative study was to evaluate the survival rate, condition of peri-implant tissues, patient satisfaction and surgical and prosthetic aftercare of the IMZ-implant system (two-stage cylinder type), the Brånemark-implant system (two-stage screw type) and the ITI-implant system (one-stage screw type) supporting a mandibular overdenture during a 10-year follow-up period. MATERIALS AND METHODS Three groups of 30 edentulous patients were treated with two endosseous implants in the interforaminal region of the mandible. Clinical and radiographic parameters were evaluated immediately after completion of the prosthetic treatment and after 1, 5 and 10 years of functional loading. Prosthetic and surgical aftercare was scored during the evaluation period, as well as patient satisfaction. RESULTS The 10-year survival rate was 93% for the IMZ group, 98% for the Brånemark group and 100% for the ITI group (IMZ<ITI, p<0.05). Mean marginal bone loss was limited over a period of 10 years. No differences in satisfaction and aftercare were observed between the groups. CONCLUSION It is concluded that two implants placed in the interforaminal region, connected with a bar, supply a proper base for the support of a mandibular overdenture in the edentulous patient. After10 years, no relevant changes had developed between the three implant systems.

The development and characterization of monoclonal antibodies against rat cytomegalovirus induced antigens

SummaryIn this paper the development of a battery of approximately 70 mouse monoclonal antibodies (McAbs) to RCMV-induced antigens and their characterization is discussed.Their reactivity with the whole scala of ca. 30 virus specific proteins was tested in an enzyme linked immunoassay (ELISA) whereas their ability to detect RCMV-antigens at different locations ofin vitro infected cell cultures and at different stages of infection was tested by immunofluorescence.In order to determine to what specific (viral) protein each of these McAbs is directed against we used an immunoprecipitation technique, followed by SDS-PAGE.Furthermore, neutralizing capacity of each McAb was tested, as well as the immunoglobulin class they belong to.In this manner we defined six categories of monoclonal antibodies on the basis of immunofluorescence aspect.The six categories identify most important viral structural proteins.

Microradiography to evaluate bone growth into a rat mandibular defect

Microradiography has been evaluated to measure bone healing into a 5.0mm outer diameter mandibular defect in the rat. This method provides high-resolution radiographs of the defects that can be used for an accurate measurement of bone defect healing. In 12 rats, the defect widths of 42-day-old mandibular defects have been measured both using microradiographs and histological sections. The defect width+/-S.D. measured 3.42+/-0.98 mm microradiographically and 3.47+/-1.11 mm histologically. Both methods were accurate in determining defect widths but microradiography has the advantage over histology that an image is obtained from the entire defect, making it possible to measure areas of bone growth.