Joseph H. Kronman

The efficacy of several irrigating solutions for endodontics: a scanning electron microscopic study.

The perforated irrigation needle was used to test a high-volume (20 c.c.) final flush of prepared root canals. Three solutions: TEGO 1 percent, NaOCl 5.25 percent, and REDTA were tested. The roots were split longitudinally and were prepared for examination under the scanning electron microscope immediately after preparation and final flushing. In addition, groups were prepared and flushed in the same manner, but after splitting they were soaked in the respective solutions for 3 hours and then examined. The results indicated that the smeared layer is caused by instrumentation, that it is not removed by TEGO or NaOCl, and that it is removed by REDTA. It may be that the smeared layer is a slurry of dentin filings, since REDTA does not remove soft tissue. All solutions produced a canal quite free of debris; however, none of the tested irrigants was completely satisfactory by itself.

Cranioskeletal displacements caused by rapid palatal expansion in the rhesus monkey

w right1 was the first to suggest that all consequences of maxillary expansion should be studied before its LISC is undertaken. He stated: “Arbitrary application of mechanical forces to teeth must be made with references to bony changes which must ultimately occur in the structures beyond the teeth.” It was on this basis that the present project was first conceived. It was hoped that, 1)~ duplicating the expansion procedures in rhesus monkeys exactly as they arc carried out in human patients, bony changes and displacements which may occur as a result of rapid palatal expansion could be ascertained. All the animals were studied under both natural and ultraviolet light to determine bony displacements or remodeling as indicated by the absorption or nonabsorption of a tetracycline dye previously injected into the animals.

New method of irrigation during endodontic treatment

A new method of intracanal irrigation using a perforated needle was examined. This system was compared with the conventional endodontic needle from both an in vitro and a clinical standpoint. Results indicated that a more complete irrigation was achieved with the perforated needle than the conventional one. Patients reported no untoward effects from the technique.

Adaptation and porosity of poly-HEMA in a model system using two microorganisms

This study was designed to evaluate the resistance of a hydrophilic plastic polymer (poly-HEMA) to bacterial invasion. A new model system was devised using specific bacteria and nutrient indicator medium. The results showed that poly-HEMA does not allow penetration of a highly motile organism.

Porion and condyle as cephalometric landmarks--an error study.

With the recent increase in the use of functional appliances for orthodontic treatment in which condylar growth plays an important role in the final results, orthodontists and researchers should be aware of the process of growth and development of various components of the skull to see the changes of measurements on cephalometric tracings in different stages of treatment. This study was conducted to assess the reliability of the porion and condyle on the lateral cephalogram. A group of 24 patients was selected randomly from the Orthodontic Department at Tufts University. Two sagittal roentgenograms, one in habitual (centric) occlusion and one with the mouth wide open, were taken. Each cephalogram was traced by two observers to determine discrepancies in tracing the shape and position of the porion and condyle. The Pearson product-moment coefficient of correlation was performed for inter- and intraobserver reliability for locating the porion and condyle in open- and closed-mouth positions. It was concluded that the porion and condyle cannot be located accurately and consistently on sagittal roentgenograms in the closed-mouth position. Therefore it appears advisable to obtain an open-mouth cephalogram and superimpose it onto the respective closed-mouth cephalogram. This will provide greater accuracy and reliability in obtaining cephalometric measurements.

Statistical evaluation of the position of the mandibular foramen.

The position of the mandibular foramen and its importance to successful inferior alveolar anesthesia has been well documented. The current study attempts to use position of the narrowest AP width of the ramus and the gonial angle as the important parameters in locating MF, rather than using isolated measurements of the bony mandible proper.

Scanning electron microscope study of a new irrigation method in endodontic treatment.

The effectiveness of a newly developed perforated endodontic irrigation needle, with its distal aperture sealed, was compared to conventional endodontic irrigation procedures. In all instances 5 percent sodium hypochlorite was used since the delivery system, rather than the irrigant, was being evaluated. A base line group in which all soft tissue was described was also included. The results indicate that the perforated endodontic irrigation needle is a very effective instrument for the cleansing of instrumented root canals.

A Comparative in vitro Study of GK-101 and GK-101E in Caries Removal

(1) This study indicated that both GK-101 and GK-101E exerted a statistically significant chemical action in the removal of carious material, in addition to any mechanical effects of the delivery system and applicator tip. (2) The superiority of GK-101E over saline in caries removal was noted, regardless of lesion consistency. (3) GK-101 was statistically superior to saline in caries removal in medium-hard lesions; it was not statistically superior to saline in lesions of medium consistency.

Electron Microscopic Evaluation of Altered Collagen Structure Induced by N-Monochloroglycine (GK-101)

The effects of N-monochloroglycine (NMG) solutions on the structure of collagen were studied by transmission electron microscopy. In addition to finding that collagen structure was altered by NMG solutions, the results offer evidence that buffer and water also exert some effect on collagen fiber structure.

Anatomic basis for disk displacement in temporomandibular joint (TMJ) dysfunction.

This study was designed to investigate the site of lateral pterygoid muscle insertion into the temporomandibular joint (TMJ) disk, and the relationship between that attachment and the disk displacement. One hundred and ten TM joints from 78 cadavers were collected and sectioned in the sagittal plane. Sixty-two unilateral specimens were available and 16 additional specimens were selected randomly from the remaining cadavers in which both condyles were available. Thus statistical comparisons were not confounded by autocorrelation and were based on 78 independent specimens. The sites of muscle attachment in relation to the disk were identified histologically. Of the 78 joints 49 had anterior disk displacement. Of the 42 cases with insertion directly into the disk, 30 had anterior disk displacement. In contrast, only 19 of the 36 disks without direct muscle insertion were displaced. This finding indicated a statistically significant relationship between functional muscle attachment and disk displacement (chi 2 = 9.28, df = 1, p = 0.006). However, the superior head of the lateral pterygoid muscle (SLP) may not be the precipitating factor for anterior disk displacement even though it does coordinate disk movement on closure. Since other factors (e.g., trauma) can result in disk displacement, the SLP can maintain disk displacement only when it inserts directly into the disk. In cases of normal disk arrangement and condylar attachment, the muscle may not play a clinically significant role in disk displacement because disk attachment at the medial and lateral poles of the condyle allows the disk to move freely with the condyle.(ABSTRACT TRUNCATED AT 250 WORDS)