A long-term study of 370 autotransplanted premolars. Part IV. Root development subsequent to transplantation

The purpose of the present study was to analyse the extent of root development subsequent to transplantation in a material of 370 transplanted premolars. Before transplantation, the grafts were classified according to stage of root development (i.e. quarters of root length and constriction of the apical foramen) and length of tooth development (measured in mm from the cusp tip to the apical foramen). At radiographic controls the extent of root formation was registered. These figures were compared to the final tooth length of 288 non-transplanted premolars from the present material as well as to tooth length determinations of 534 premolars extracted for orthodontic purposes. Furthermore, intra-individual and inter-individual differences in tooth length were examined in a skull material with 40 pairs of premolars. These method studies indicated that root growth was probably determined genetically with great right-left accuracy and variation related to location of premolar (maxilla or mandible) and sex. A statistical analysis of the transplant material revealed that stage as well as length of tooth development assessed prior to transplantation were significantly related to final tooth length after transplantation. In most cases of transplantation performed at early stages of root development, a reduction in the final root length was seen. When a qualitative analysis of root development was performed in teeth with incomplete root formation at the time of transplantation, and where a homologous non-transplanted premolar was present, it was found that 14 per cent showed total arrest of root formation, 65 per cent partial arrest whereas 21 per cent showed no arrest (i.e. normal root formation). Premolars in ectopic position in the mandible before transplantation showed a significantly reduced root growth compared to matched pairs with normal position of the tooth graft. The present study indicated that no, partial or total damage to the Hertwig's epithelial root sheath was probably the explanatory factor for variations in root growth.

A long-term study of 370 autotransplanted premolars. Part II. Tooth survival and pulp healing subsequent to transplantation

The purpose of the present investigation was to determine the long-term prognosis of autotransplanted premolars with respect to tooth survival and pulpal healing. The material consisted of 195 patients aged 7 to 35 years, with a total of 370 autotransplanted premolars with observation period ranged from 1 to 13 years. Teeth transplanted with incomplete and complete root formation showed 95 per cent and 98 per cent long-term survival respectively: Pulp healing as evaluated by sensibility testing and radiographic signs of partial pulp canal obliteration was usually verified 6 months after transplantation. The frequency of pulpal healing (versus pulp necrosis), appeared to be closely related to stage of root development at time of transplantation. Teeth transplanted with incomplete and complete root formation showed 96 per cent and 15 per cent pulp healing respectively. Another and associated factor which could equally well predict pulpal healing was the diameter of the apical foramen of the graft. Finally, in teeth with completed root formation, the use of bursa with internal cooling and no extra-alveolar storage prior to transplantation seemed to increase the chance for pulpal healing. The present study indicates, that the size of the apical foramen and possibly the avoidance of bacterial contamination during the surgical procedure are explanatory factors for pulpal healing.

A long-term study of 370 autotransplanted premolars. Part I. Surgical procedures and standardized techniques for monitoring healing

Tooth autotransplantation has recently become a method of treating certain orthodontic problems. Over a 13-year period 370 premolar transplants were monitored by electrometric pulp sensibility testing and radiographic examination for pulp and periodontal ligament healing as well as root growth. This article describes the surgical technique as well as the precision of sensibility testing and radiographic examination for evaluating transplant healing. The sensibility response was found markedly related to the stage of tooth development but not to the type of premolar. The precision of sensibility testing (i.e. deviation of two consecutive measurements at a few weeks' interval) was found to range from 15-36 per cent for the different stages. Film holders were used to standardize the intraoral radiographic exposures. The precision percentage for the measuring technique of tooth length and crown width based on a single radiograph read twice (reading error) ranged from 1.1 to 1.8 with only small variations among the different types of premolar. The precision percentage of the radiographic exposure technique evaluated from two consecutive radiographs (measuring plus exposure error) was found to range from 1.2 to 4.2, again with small variations among the different premolars. The accuracy of the radiographic technique (i.e. deviation of radiographically determined tooth dimensions from the true values) was found to range from 2.0 to 2.9 with only small variation between the various types of premolar. In conclusion the evaluation of electrometric sensibility testing should take into account the stage of root formation of premolars.

A long-term study of 370 autotransplanted premolars. Part III. Periodontal healing subsequent to transplantation

The purpose of the present investigation was to determine the long-term prognosis of autotransplanted premolars with respect to periodontal healing. The subjects consisted of 195 patients aged 7 to 35 years, with a total of 370 autotransplanted all operated and followed with a standard technique. The observation period ranged from 1 to 13 years. Periodontal healing as demonstrated radiographically was complete in most cases after 8 weeks. Root resorption occurring after transplantation was divided into surface-, inflammatory- and replacement resorption (ankylosis). Root resorption occurred in 52 of the transplanted teeth and was usually diagnosed within 6 months. Root resorption was found to be significantly related to increasing stage of root development and the stage of eruption at the time of transplantation. Subsequent orthodontic movement of teeth with completed root formation at the time of transplantation resulted in a slight increase in the frequency of both surface and inflammatory resorption. The present study indicates that trauma to the PDL of the transplant is the explanatory factor for the development of root resorption.

Comparative inhibition of ras p21 protein synthesis with phosphorus-modified antisense oligonucleotides

A rabbit reticulocyte lysate translation assay was used to quantitatively compare a series of antisense oligodeoxyribonucleotides (11-mers) having different internucleoside linkages and various degrees of complementarity (100-80%) with the start codon and downstream 8 bases of Balb-ras p21 mRNA. The oligomers had either contiguous phosphodiester, or alternating methylphosphonate-phosphodiester, or contiguous methylphosphonate, or contiguous phosphorothioate linkages. Under the conditions used for the assay, all of the test compounds when present in about 10(3)-10(4) excess over mRNA (15 nM mRNA) inhibited protein synthesis to a degree which was dependent on both the concentration and sequence of the oligomer. At low concentrations (12.5-25 microM), the phosphorothioate analogs were the most potent inhibitors of p21 protein synthesis; however, a sequence non-specific effect for these oligomers was dominant at higher concentrations of oligomer (100-200 microM). The methylphosphonate oligomers appeared to be slightly more discriminant. Relative hybridization strengths were assessed by melting (Tm) studies using a DNA oligomer target to mimic the mRNA.

Novel inhibitors of enkephalin-degrading enzymes. II: N5'-substituted-4-thioxohydantoic acids as aminopeptidase inhibitors

Some 2-substituted-(2'-aminophenyl)-4-thioxohydantoic acids (o-amino PTC-amino acids) have antinociceptive activity when administered (icv) alone (IC50 = 0.04-0.87 microM/animal) and show a striking prolongation of the antinociceptive action of (D-Ala-2 D-Leu5)-enkephalin (DADL) in combination. The effects are thought to be mediated via opioid receptors since they are naloxone-reversible. Although inhibitors of the enkephalin degrading puromycin-insensitive, bestatin-sensitive aminopeptidase (possibly aminopeptidase M) their action is weak (IC50 = 32 microM leucine, 536 microM, glycine) and they might be considered to have a direct antinociceptive effect on opioid receptors. The titled compounds constitute novel 'lead' compounds for the development of potent aminopeptidase M inhibitors.

The results of radiation therapy in advanced carcinoma of the lung in the Beijing region of China

From 1958 to 1973, 682 patients with lung cancer were treated by radiation therapy in the Cancer Institute, Chinese Academy of Medical Sciences, Beijing, China. The clinical presentation, sex, age, histology and stage and palliative effects of radiation therapy were reported. The 1-, 3- and 5-year survival rates were 40.62, 8.94 and 3.81%, respectively. The prognostic factors such as staging, histology, combination with chemotherapy and response of tumours are discussed. The causes of failure are also analysed. It is suggested that improving the local control rate of squamous cell carcinoma would increase the survival rate.