Aqueous-only, pH-induced nanoassembly of dual pKa-driven contraphilic block copolymers.

pH-Responsive block copolymers, having two segments with functionalities of differing pK(a), were prepared by NMP, providing a "green" route to the assembly of core-shell functionalizable nanostructures.

Fractures of the condylar process: surgical versus nonsurgical treatment.

PURPOSE: The purpose of this study was to compare outcomes from surgical and nonsurgical treatment of condylar process fractures. PATIENTS AND METHODS: Two hundred thirty-four patients with fractures of the mandibular condylar process were treated by open or closed methods. In the follow-up study, 150 patients with a mean follow-up time of 2.5 years were analyzed using radiologic and objective and subjective clinical examinations. RESULTS: No significant difference in mobility, joint problems, occlusion, muscle pain, or nerve disorders were observed when the surgically and nonsurgically treated patients were compared. The only significant difference was in subjective discomfort. Surgically treated patients showed significantly more weather sensitivity and pain on maximum mouth opening. CONCLUSION: Because of its disadvantages, open surgery is only indicated in patients with severely dislocated condylar process fractures.

Indications and limitations of three-dimensional models in cranio-maxillofacial surgery.

Anatomical, life-like, three-dimensional (3D) models have a definite place in cranio-maxillofacial surgery. Our experience with 541 computer tomography (CT)-based 3D models employed in aiding corrective surgery of tumours, dysgnathia, traumatology, alveolar atrophy, congenital malformation and asymmetrical malformations in our department is discussed. From July 1988 to February 1997, 3D models of 346 patients were used. Most of these were produced at our clinic. The indications, advantages and limitations of 3D-models were analysed retrospectively. In the case of congenital malformations (n = 60), models facilitated precise diagnosis of the skeletal deformity. Simulation surgery allowed prediction and solution of intraoperative problems prior to the actual patient operation. Size, shape and localization of defects caused by trauma (n = 64), osteoradionecrosis (n = 17) or osteomyelitis (n = 2) determined the choice of transplant donor site. In patients suffering from dysgnathia (n = 144), 3D models enabled exact positioning of the jaws. Precise planning could only be accomplished with the help of 3D models, especially for asymmetrical malformations (n = 12). In cases of severe atrophy of the alveolar crest (n = 45), exact measurement of the bone was possible and facilitated the decision as to whether dental implants, bone transplants or a combination of these were indicated. The positioning of transplants and implants was carried out in the ideal relation to the opposite jaw. In tumour patients (n = 186), it is not always possible to identify the tumour borders precisely on the CT scan or 3D model. Therefore, the defect was assumed to be bigger, a longer bridging plate constructed and this measurement corrected according to the intraoperative situation. The advantage of the 3D models consisted of an accurate representation of anatomical structures, bone or soft tissue. This allows precise preoperative diagnosis, operation planning and model operations. Due to this, the correct approach as well as operation technique could be chosen, outcomes of constant high quality were achieved, and there was a reduction in operation time.

A study of replanted permanent teeth in different age groups.

The purpose of this study was to evaluate the benefits of replanting avulsed permanent teeth in different age groups. Of the 112 replanted teeth, 103 could be examined after 2.5 years on average. The teeth were divided into three groups: immature teeth (group A), mature teeth in children and adolescents (group B), and mature teeth in adults (group C). Concomitant injuries did not differ statistically between the groups. Extra-alveolar time with unphysiologic storage was longer than 15 min in 81 teeth. The results were statistically different for pulpal healing (A >> B > C), loss of marginal bone (C > A), amount of replacement resorption (A and B > C), alveolar growth inhibition (A > B >> C), local gingivitis (B > A and C) and buccal gingival retraction (C > A and B). Only 3 of 23 extracted teeth were lost because of replacement resorption alone. Only 2 of the 23 extracted teeth showed revascularization of the pulp. The results suggested that replanting avulsed teeth should be considered a temporary solution in children and adolescents. In these patients, the benefit of tooth replantation is mainly the time gained to establish an optimal treatment plan. Mature teeth with a necrotic periodontal ligament replanted in children before the pubertal growth spurt seemed to have the poorest prognosis.

[Replantation of avulsed immature permanent teeth. Results in 39 cases after an average of 2.5 years]. / Replantation totalluxierter unreifer bleibender Zähne. Durchschnittliche 2,5-Jahres-Ergebnisse in 39 Fällen.

The aim of this investigation was a critical assessment of the short- and medium-term results of replantation of immature, avulsed permanent teeth. Thirty-nine teeth were investigated after 2.5 years on average. Only 7 teeth (18%) had been replanted within 5 min after avulsion. Sixteen teeth (41%) showed revascularisation or ingrowth of alveolar bone into the pulp. Twenty-two teeth (56%) showed signs of ankylosis, 6 (15%) had been exfoliated or extracted. Seventeen teeth (77% of the ankylotic ones) exhibited an alveolar growth arrest of 1.5 mm per 10 cm body growth. By planimetric assessment, the yearly loss of root dentin by replacement resorption was about 15%. The appearance was compromised in 11 cases (33%) by severe discoloration. In spite of intense therapeutic effort and partial success, the results must be classified as unsatisfactory. In avulsions of immature permanent teeth, replantation therefore has to be considered an intermediate solution. Since the main reason for a failure is extended extra-oral unphysiologic storage, replantation by lay helpers immediately after the accident should be propagated as a first-aid treatment to improve the situation of the replanted tooth. In addition, more attention should be paid to preserving teeth in tissue cultures before replantation.