Surface Wear and Retention Force of Zirconia and PEKK Implant-retained Crowns.

PURPOSE: The aim of this study was to evaluate the surface wear and retention force of telescopic attachments made of zirconia primary crowns and poly-ether- ketone -ketone (PEKK) secondary crowns for 2-implant retained mandibular complete overdentures. MATERIALS AND METHODS: Ten healthy completely edentulous patients aged 55-60 years were selected for this study. Each patient received two implants in the mandibular canine regions. Maxillary conventional complete dentures were constructed against implant-retained mandibular overdentures for all patients. Zirconia- PEKK telescopic attachments were fabricated to retain the overdentures where primary copings were constructed of zirconia and secondary ones were constructed of PEKK. Retention force and surface wear were evaluated at the time of overdenture insertion (T0), and after 6 months of overdenture use (T6). RESULTS: The results revealed less wear of zirconia copings compared to PEKK ones at T0 and T6. However, both materials showed insignificant wear after 6 months of overdenture use. A significant increase in retention force was observed after 6 months of overdenture use. CONCLUSION: Within limitations of this study, PEKK may be considered a promising alternative material for telescopic secondary crowns construction combined to zirconia primary ones, regarding the wear resistance and the satisfactory retention forces.

Aponeurotic hernias. Recent observations upon paraumbilical and epigastric hernias.

The mechanism of herniation through the anterior abdominal wall aponeuroses remains inadequately explained. Recently, when the structural significance of the anterior abdominal wall aponeuroses was recognized, some light was shed. The etiology and surgical repair of aponeurotic hernial defects were restudied on a structural-functional biomechanical basis.

A new concept of the aetiology and surgical repair of paraumbilical and epigastric hernias.

The aetiological factors concerned in the production of paraumbilical and epigastric hernias have been reviewed along structural--functional lines. A positive relation between the aponeurotic pattern and herniation was demonstrable at operation in 25 patients with paraumbilical or epigastric hernias. The effect of abdominal distension, obesity, and straining are discussed. A new type of surgical repair planned on this basis is described. The preliminary results obtained with this technique are reported, with a discussion of other previously described types of surgery.

Surgical anatomy of the aponeurotic expansions of the anterior abdominal wall.

Dissection of the anterior abdominal wall in 40 fresh cadavers, with confirmation of the anatomical findings at operation in 25 patients, has enabled the patterns of distribution of the aponeurotic expansions of the abdominal muscles to be traced and the relation of structure to function to be determined. It is pointed out that the linea alba should no longer be regarded as the line of insertion of the abdominal muscles but as the area of decussation of the tendinous aponeurotic fibres of the muscular strata passing from one side to the other, for which the name "midline aponeurotic area" is proposed. Two separate functional areas are described, a "parachute respiratory mechanism" in the upper abdomen and a belly support in the lower abdomen. Attention is drawn to the functional derangement that may follow some of the standard abdominal incisions and to possible mechanisms of herniation through the midline aponeurotic area.

A clinico-radiological survey of deep venous thrombosis of the leg.

In a clinico-radiological survey of 150 cases of varicose veins of the leg, 44 had primary varicosities with no dermal complications; their venograms showed patency of the deep veins of the leg. In 106 cases presenting dermal complications, venographic evidence of deep venous occlusion was present. The dermal complications of varicosities are, therefore, always secondary to deep venous occlusion. Deep venous occlusion of the leg was confined to the lower 1/3 of the leg in 58% of the cases occurring as a complication of silent varices. In 15% it involved the upper 1/3. This lesion complicated trauma and surgical operations. In 5% thrombosis occurred in the muscular sinusoids as a complication of septicaemia. In 22%, deep venous occlusion in lower 1/3 of the leg extended to the middle and upper thirds with a corresponding ascending aggravation of the clinical picture. The underlying factors in the pathogenesis of dermal complications are discussed as well as the role of the lymphatics. The reported classification of deep venous occlusion of the leg may prove of value if a venographic study is not feasible. A review of the various types of treatment is presented in the light of these informations.