J.R. de Wijn

Porous acrylic cement for the correction of craniofacial deformities and repair of defects, animal experimentation and two years of clinical application

Abstract A recently developed self-curing porous acrylic bone cement promises a valuable improvement in craniofacial reconstruction. In situ curing and the open sponge-like porosity are advantageous for good contour reconstruction and fixation to the underlying bone. To date 12 selected patients with a variety of craniofacial deformities have been operated on. The preliminary results of clinical work are presented.

Physicochemical properties and mineralization assessment of porous polymethylmethacrylate cement loaded with hydroxyapatite in simulated body fluid.

The aim of this study was to evaluate the effect of carboxymethylcellulose (CMC) as a pore generator and hydroxyapatite (HA) as an osteoconductive agent on the physicochemical properties and in-vitro mineralization ability of porous polymethylmethacrylate (PMMA) cement. To this end, various compositions of PMMA cements, which differed in amount of millimeter-sized hydroxyapatite (HA) particles and CMC hydrogel, were prepared and immersed into simulated body fluid (SBF) for 0, 7, 14, 21 and 28 days. It was demonstrated that the incorporation of CMC hydrogel decreased the maximum temperature of cement to the normal body temperature and prolonged the handling time during polymerization. Further, the amount of CMC was responsible for the creation of porosity and interconnectivity, which in turn determined the final mechanical properties of cements. The loaded HA particles enhanced the potential bioactivity of cement for bone ingrowth. Albeit different amount of HA particles influenced their final exposures on the surface of cured cement, all of the three amounts of HA did not weaken the final mechanical properties of cements. The data here suggests that the HA particle loaded porous PMMA cement can serve as the promising candidate for bone reconstruction.

A mechanical investigation of the functioning of mouthguards

Mouthguards may play an important role in the prevention of injuries to the teeth and the related tissues of people participating in various branches of sport. Several publications provide statistical data concerning the effect of mouthguards in protecting the head and neck region, including the teeth of e.g. American football players (Ref. 1, 2, 3).Also, much information is available on the mechanical properties of potential mouthguard materials (Ref. 4, 5, 6). However, basic investigations to the mechanics of teeth protection by mouthguards have only scarcely been done (Ref. 7). It was the aim of this study to investigate the functioning of mouthguards, the attenuation of impact forces, non-destructively in terms of both local attenuation in the contact area and distribution of impact forces over adjacent teeth.

Porous root replacements: reactions of the surrounding tissues

Artificial tooth roots may help to preserve the volume of the alveolar ridge after the loss of the natural teeth. The suitability of mouldable porous polymethylmethacrylate (PMMA) cement to replace tooth roots is examined in an animal experiment. A description of the material, the method of application and the reactions of the surrounding tissues at several experimental periods up to 54 weeks are presented.

Release of an anti-inflammatory drug from some dental cements

Abstract Controlled release of the anti-inflammatory agent Tantum was studied from a number of commercially available dental cements used as matrices. Low water sorption cements released only minor amounts. Cavit released the major part (75%) within the first two days. The release from Durelon was pH dependent: at pH 4,8 20% was released after one day, at pH 7.0 55% after 2 days, which in both cases was followed by a slower release.

The Mechanical Performance of Solid and Porous Bone Cement

In an attempt to overcome some of the shortcoming of bone cement a porous bone cement was developed at our laboratories (1). In several previous studies we reported about the evaluation of this cement (2–6).