Prefabricated Crown User Guide - 3M ESPE Prefabricated Crowns - User Guide 5 care

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  • A comprehensive guide to achieving the b est results with 3M™ ESPE™ Prefabricated Crowns.

    Crowns User Guide


  • 3M ESPE Prefabricated Crowns - User Guide 1

    3M™ ESPE™ Stainless Steel Crowns 3

    3M™ ESPE™ Stainless Steel Primary Molar Crowns 3

    3M™ ESPE™ Stainless Steel Permanent Molar Crowns 6

    3M™ ESPE™ Polycarbonate Crowns 8

    3M™ ESPE™ Iso-Form™ Crowns 10

    Other 3M ESPE Crowns 13

    3M™ ESPE™ Gold Anodized Crowns 13

    3M™ ESPE™ Unitek™ Stainless Steel Crowns 13

    3M™ ESPE™ Strip Crowns 13

    Ordering Information 14

    Introductory Kits 3M ESPE Stainless Steel Crowns Primary Molars 14 Permanent Molars 14

    3M ESPE Polycarbonate Crowns 14

    3M ESPE Iso-Form Crowns 15

    3M ESPE Unitek Stainless Steel Crowns Primary Molars 15 Permanent Molars 15

    3M ESPE Gold Anodized Crowns 16

    3M ESPE Strip Crowns 16

    Refills 16

    3M™ ESPE™ Crown Instruments 17

    Table of Contents

  • The morphology of a primary molar differs significantly from that of a permanent molar tooth.

    The cervical areas of primary molars are narrower than their permanent counterparts, but the most bulbous part of the crown is at the cervical third. (1) It is beneath this bulbous area at the gingival margin where the stainless steel crown obtains its retention.

    The enamel and dentin of primary teeth are thinner than in the permanent dentition and the primary molar pulp chamber is comparatively large. (2) The mesial pulp horn extends toward the contact point area and the distal pulp horn lies under the center of the occlusal surface. Because the dentin is relatively thin it can be difficult

    to achieve adequate retention in a proximal cavity even when the cavity is only moderately deep. (3)

    Longevity of Primary Molar Restorations

    A number of authors have compared longevity of amalgam and stainless steel crown restorations in primary teeth. Braff in 1975 (4) found that 88% of amalgams placed in children needed follow-up treatment compared with 30% of the stainless steel crowns. Dawson et al (5) found that for restorations placed in children of average age 5.5 years, 58% of Class I and 70% Class II amalgams in primary molars needed further treatment before eight years old.

    However, only 11% of stainless steel crowns needed further treatment. The authors concluded that stainless steel crowns are the treatment of choice for primary molars, especially for multi-surface lesions in the first primary molar.

    Holland et al (6) found the median survival time for amalgams in the primary molars of three-year-old children was 11 months, and for seven- and eight-year-old children was 4 months. More recently, Roberts and Sherriff (7) found from evaluating patient records in a pedodontic practice, that the replacement rate for Class I and II amalgams at five years in primary molars was 15.4% compared with 2.8% for stainless steel crowns over the same time period.

    3M ESPE Stainless Steel Crowns are designed to provide long-term coverage of primary molar teeth and long-term provisional coverage of permanent molar teeth.

    Different designs of prefabricated metal crowns have been offered to the dental profession over the years ranging from straight sided “bucket” crowns to the anatomically shaped 3M ESPE stainless steel crowns available today.

    3M ESPE stainless steel crowns have been designed to accurately duplicate the anatomy of primary and first permanent molars in a selection of sizes (fig. 1). The crowns are manufactured with a life-like height, contour and occlusal surface. They are pre-crimped at the cervical margin to give good retention and a “snap” fit.

    The realistic anatomical shape of a

    3M ESPE stainless steel primary molar crown means that minimal adjustment is necessary to obtain good retention. There is good harmony with the patient’s occlusion and the smooth

    stainless steel alloy surface helps maintain gingival health and patient comfort (fig. 2).

    3M ESPE Prefabricated Crowns - User Guide 3

    3M™ ESPE™ Stainless Steel Crowns

    3M ESPE Stainless Steel Primary Molar Crowns

    (fig. 2)

    (fig. 1)

  • Eriksson et al (8) compared 104 crowned primary molars with 104 control teeth; 20 of the control teeth being sound and 84 having amalgams placed. The teeth were monitored over time until exfoliation. Initial treatment involved 107 visits to place 104 crowns and 85 visits to place 84 amalgams. Only 21% of the crowned teeth needed further treatment compared to 77% of the amalgam restored teeth. The additional time spent on further treatment for the amalgam group was 9.5 hours more than for the crown group.

    In a 1996 study performed by Einwag and Dünninger, it was concluded that stainless steel crowns proved far superior to multi-surface amalgam restorations with respect to both lifespan and replacement rate. (9) The study comprised 106 patients, 66 of whom were traced and included in the final evaluation. Approximately 83% of the stainless steel crowns had a lifespan of at least 8 years. Amalgam restorations survival rate after only one year was 80%. After 4.5 years, the rate was below 40%. In contrast, the survival rate for the stainless steel crowns at 4.5 years was more than 90%. The difference in replacement rate between the stainless steel crowns and amalgams was highly significant. Only 4 of 66 crowns (6%) had to be replaced compared to 38 of 66 amalgam restorations (58%).

    Indications for Use

    1. Where an amalgam is likely to fail in a primary molar, such as a Class II cavity where the proximal box is extended beyond the anatomic line angles. (10, 11)

    2. Extensive caries damage involving multiple surfaces of the tooth.

    3. Extensive decalcification around an already restored tooth where there is a high risk of recurrent caries. (10)

    4. For space maintenance.

    5. After pulp therapy or endodontic procedures on a primary molar.

    6. Developmental defects such as amelogenesis imperfecta, dentino- genesis imperfecta, or hypocalcified teeth. (11, 12) Stainless steel crowns are useful as an “emergency” measure to reduce the sensitivity of these teeth and allow the patient to eat and main- tain effective oral hygiene measures.

    Consider alternative treatment if:

    1. Patient is unable to cooperate with treatment.

    2. Primary tooth is approaching exfoliation; i.e., X-ray shows over half the primary tooth root resorbed.

    Technique for Use

    Effective local anesthetic should be given as the preparation will extend subgingivally.

    Occlusal reduction is carried out to obtain clearance of approximately 1.5 mm (fig. 3).

    If a rubber dam has been placed, the preparation can be compared with the occlusal height of the neighboring teeth. The mesial and distal contact points are cleared and a smooth taper from occlusal to gingival should be obtained that is free of ledges or shoulders (fig. 4).

    All caries are removed and the line angles rounded off. Often half or more of the tooth preparation is completed simply by caries removal. It is possible to lose a large amount of the clinical crown, yet still be able to fit a stainless steel crown.

    Stainless steel crowns are not close fitting, therefore the preparation does not have to be precise. The gingival finishing line should be a feather edge with no ledges or steps detectable. A reasonable taper mesially and distally will help to achieve this. If a step or ledge is present (fig. 5), the operator will have difficulty seating the crown and may be tempted to trim it unnecessarily.

    No preparation is usually needed on the buccal or lingual surfaces of primary molars except where there is a pronounced mesio-buccal convexity as seen on some primary first molars. The stainless steel crowns are flexible enough to spring over minor contours. (10)

    When multiple crowns are to be placed in the same quadrant, the adjacent proximal surfaces of the teeth being prepared should be reduced slightly more than usual. This will make multiple crown placement easier. (10)

    The finishing line should be approximately 1 mm below the gingival margin.

    The correct size crown is selected by measuring the mesio-distal width between the contact points of the neighboring teeth with calipers. If teeth are missing, the mesio-distal width of the matching tooth in the opposite arch can be measured. It is advisable to choose the smallest crown that will fit. If the crown is too large it is very time consuming to adjust it to obtain good retention.

    When fitting a crown for a second primary molar, where the first permanent molar has not yet erupted,

    3M ESPE Prefabricated Crowns - User Guide4

    (fig. 3)

    (fig. 4)

    (fig. 5)

  • 3M ESPE Prefabricated Crowns - User Guide 5

    care must be taken when measuring the available mesio-distal dimension for the crown. If the stainless steel crown encroaches on the space needed for eruption of the permanent molar, its eruption path may be distorted.

    To seat the crown on a prepared tooth it is placed lingually and rolled over the preparation to the buccal margin.

    A crown will often make an audible “click” as it springs into place over the gingival undercut area. Firm pressure is usually needed to seat the crown.

    The margina