Maryland Bridge Research Articles

Two unique clinical applications using acid-etched restorations

Two "Maryland bridges" replacing anterior teeth fused to the facial surface of the abutments are described.

Shear bond strengths and scanning electron microscope evaluation of three different retentive methods for resin-bonded retainers

T he “Maryland bridge” with resin-bonded retainers has been well described in the literature.‘-‘3 Electrolytically etching the base metal markedly improved the bond strength between the metal and resin.8J0 However, to avoid contamination by saliva and foreign substances on the internal surface of the retainer, etching has been advocated after a try-in appointment.‘0~‘2 Because of the laboratory equipment needed and the sensitivity of the electrolytic technique, dentists have limited control of the quality of the metal etch. Table I. Composite shear bond strengths (megapascals)

An alternative to cast etched retainers

0 ne of the most significant advances in prosthodontics is the development of the resin-bonded retainers or “Maryland Bridge”.‘-3 This system precludes the need for extensive preparation of the abutment teeth. Other advantages include reduced patient treatment and laboratory time and cost. Clinical studies have demonstrated the effectiveness of this treatment,4 which is used in several countries around the world.5, 6 Table I. Materials included in the study

Saliva contamination and resin bonding of etched metal retainers

This study was performed to determine how preapplication of unfilled resin and subsequent saliva contamination would affect the shear strength of the etched-metal resin-bonded retainer. There was no significant difference in the shear strength of the metal-resin bond among experimental groups when the metal retainer was bonded in the routine manner, when unfilled resin was applied and allowed to polymerize before bonding of filled resin, or when saliva contamination occurred before the addition of filled resin. Preapplication of unfilled resin to etched metal retainers may serve as a means of protecting the etched metal surface for routine try-in of "Maryland bridges" before final cementation.

New technique for semipermanent replacement of missing incisors

An investigation was carried out to study the efficiency of a new technique for semipermanent replacement of missing incisors. A flexible system allowing slight physiologic movement of the bridge units was created by bonding an acrylic tooth to the abutments by means of three orthodontic wires, as shown in Figs. 9 to 11. Between June, 1981, and December, 1982, fifty-three bridges of this type were inserted in a sample that was nonselected relative to overbite and overjet. It comprised fifty-one persons 10 to 22 years of age (mean, 16; SD, 3.9). During an observation period of 5 to 22 months (mean, 15; SD, 4.8) ten bridges came loose, giving a failure rate of 18.9% for the whole sample. All the loosened bridges were replacements for missing maxillary central incisors. The thirteen bridges replacing missing maxillary lateral incisors and two bridges inserted in the mandible functioned without problems. There was no correlation between failure rate and overjet and overbite. However, the functional occlusion was of importance. If there was antagonistic contact with the pontic during functional movements, the failure rate was 57.1%. If there was no such contact, however, the failure rate was only 5.4%. This difference was statistically significant. Accumulation of plaque was significantly higher around the abutments than on contralateral surfaces. However, no significant differences in gingival health were recorded. In two persons, dental caries was recorded on the abutment surface facing the pontic. The versatility of this system in several clinical situations was discussed, and detailed recommendations for fabrication and bonding were given. While this report should be regarded as preliminary, the clinical results are encouraging. It would seem that our version may offer some definite advantages over other new alternatives for bonded single-tooth replacements, such as the Rochette and Maryland bridges, in that it is simple, inexpensive, hygienic, easily repairable, and can be placed out of occlusion or reinforced with further wires, if necessary.

Bat-associated histoplasmosis in Maryland bridge workers : Sorley DL, Levin ML, Warren JW, Flynn JPG, Gerstenblith J: Am J Med 67: 623–626, 1979

Bat-associated histoplasmosis in Maryland bridge workers : Sorley DL, Levin ML, Warren JW, Flynn JPG, Gerstenblith J: Am J Med 67: 623–626, 1979

Bat-associated histoplasmosis in Maryland bridge workers

An epidemic of acute prolonged febrile respiratory disease affecting nine of 19 workers on a Maryland State bridge maintenance crew was diagnosed as histoplasmosis by serologic testing in all and by isolation of the organism in one. In our investigation, it was revealed that work on a particular bridge was associated with disease. Culture of bat guano from the site two months later revealed H. capsulatum. Four previously uninfected epidemiologic investigators also became ill with histoplasmosis following collection of soil and bat guano. This outbreak reveals that bats and bat guano are a source of histoplasmosis, suggests that only brief exposure is necessary for acute infection and reemphasizes that histoplasmosis is not confined to the midwestern states.