James R. Moergeli

Significance of the Frankfort-mandibular plane angle to prosthodontics

Cephalometric information, specifically, vertical facial types and the Frankfort-mandibular plane angle, pertinent to prosthodontics has been discussed. The Frankfort-mandibular plane angle (FMA) is formed by the intersection of the Frankfort horizontal plane and the mandibular plane. This angle can be traced and measured by means of a diagnostic overlay. An FMA of 25 +/- 5 degrees is within normal range. A high-angle patient has an FMA of 30 degrees or more, and a low-angle patient has an FMA of 20 degrees or less. A high FMA is characterized by open-bite skeletal patterns, and a low FMA by closed-bite skeletal patterns. The clinical manifestations pertinent to prosthodontics in high- and low-angle (FMA) patients are shown in Table I. However, not all clinical characteristics are present in a given patient. The classification in Table I is a beginning. The authors consider the prosthodontic study of cephalometrics an unexploited research tool. Hopefully, in the future, it will help to bridge the gap of the biological-technical interplay that is such an integral part of prosthodontics.

An improved obturator for a defect of the nasal septum

An improved technique for treating an intranasal septal perforation defect has been described, including an impression method using Silastic 382 medical grade elastomer. A clear, polished acrylic resin obturator is fabricated with retrieval holes and an orientation guide. This type of intraseptal nasal obturator is comfortable and can alleviate symptoms created by nasal septal defects.

Effect on the fit of removable partial denture frameworks when master casts are treated with cyanoacrylate resin

Master casts of improved dental stone were made from irreversible hydrocolloid impressions of a metal model. Half of the master casts were treated with cyanoacrylate resin and half were untreated controls. They were sent to a dental laboratory for framework fabrication. The returned frameworks were examined for acceptability and their completeness of seating was determined. The frameworks fabricated on the treated master casts fit significantly better than the controls. The improved seating may be attributed to an increased surface hardness, increased abrasion resistance, and improved surface morphology, but further study is necessary.

Changes in pH of irreversible hydrocolloid impression materials during setting

Two ophthalmic and four dental irreversible hydrocolloid materials were tested in vitro to determine the initial pH and changes in pH to completion of set over 4 minutes. The ophthalmic Moldite material became more basic during its setting whereas the ophthalmic Moldeye material remained stable throughout the setting. The other materials tested decreased in pH with time.

Composite dowels and cores: Effect of moisture on the fit of cast restorations

A study was undertaken to evaluate the effect of interim restorations on the dimensional stability of composite post and core buildups subjected to moisture during the fabrication of cast restorations. Dimensional change associated with composite dowel and core buildups did not significantly alter the fit of cast restorations compared with natural teeth under the same conditions. The use of composite dowels and cores for the restoration of endodontically treated teeth is not contraindicated because of potential dimensional instability of the resin when exposed to moisture. Well-fitting interim restorations for either natural teeth or composite dowel and core buildups improved the fit of cast restorations 23% to 36%.

Prosthetic requirements for selective placement of interstitial needles in the treatment of osteogenic sarcoma of the mandible

Abstract Dentists may perform an important adjunctive role in support of other medical specialists. In a combined treatment of osteogenic sarcoma of the mandible, a course of radiation to the mandible is followed by resection. A prosthesis for selective placement of interstitial radium needles is fabricated. The rationale for treatment and the prosthesis design requirements have been presented.

Irritation of ocular tissue by irreversible hydrocolloids

Two ophthalmic and two dental irreversible hydrocolloid materials were tested on rabbit conjunctivae to determine histologically their potential to irritate these tissues. Each of the four impression materials elicited nearly the same amount of inflammatory response. The differences between the response of the controls and the response to Ophthalmic Mold-Eye, Jelset Special Formula, and Kerr Alignate Type II were significant. These results indicate that certain dental irreversible hydrocolloids may be used for ocular prostheses but that they should be used with caution because of the inflammation caused by irreversible hydrocolloids.

A study of the acceptability of lateral interocclusal records by the Hanau H-2 articulator.

The acceptability of lateral interocclusal records by the Hanau H-2 articulator was studied on 28 edentulous patients. Acceptability was determined in both right and left lateral jaw movements. Of the 56 lateral interocclusal records made, 39 (70%) were accepted by the Hanau model H-2 articulator.