Gold alloy and Teflon matrices showed the highest retention values without retention loss after 3 years of simulated function. Titanium and O-ring matrices presented a continuous loss of retention with the highest wear on the ball attachments when combined with the titanium matrix.

A retrospective clinical evaluation of 1,314 cast gold restorations in 114 patients placed by one practitioner was conducted. A very high percentage of patients contacted (114/116 [98.3%]) participated in the evaluation. Almost 90% of the restorations had been in service for over 9 years, 72% for over 20 years, and 45% from 25 to 52 years. All restorations had been cemented using zinc phosphate cement. The restorations were evaluated by independent evaluators in terms of marginal integrity, anatomic form, and surface texture, and 96% of the evaluations were excellent (Figures 1-5). Sixty restorations required removal and replacement, yielding an overall failure rate of 4.6% or a survival rate of 95.4%. The survival rates at various time periods were 97% at 9 years, 90.3% at 20 years, 94.9% at 25 years, 98% at 29 years, 96.9% at 39 years, and 94.1% for restorations in place > 40 years. It appears that properly fabricated cast gold inlays, onlays, partial veneer crowns, and full veneer crowns can provide extremely predictable, long-term restorative service. It is suggested that the use of such restorations should not be automatically precluded simply because they are gold colored. These restorations should be considered in patients who are more concerned with longevity than esthetics, and in those patients in whom placement of a conservative cast gold restoration would not result in an unesthetic display of metal.

Objectives Evaluate the effects of two different machined‐collar lengths and designs on peri‐implant healing. Material and Methods An implant with a microtextured surface and 3.6mm‐long internal‐connection machined collar was compared to two implants that had an identical 1.2mm‐long external‐connection machined collar, but one had the microtextured surface while the other's was machined. Participants received the three implants, with microgap at the crest, alternately at five sites between mental foramen, and a full‐arch prosthesis. Peri‐implant bone levels were measured after 23 to 26 years of function. Keratinized tissue height, plaque, probing depth, bleeding, and purulence were also evaluated. Descriptive and mixed models for repeated\measures analyses were used, with Bonferroni correction for pairwise comparisons. Results Twenty‐two participants (110 implants) were evaluated at the 25‐year examination. Microtextured implants with the longer machined collar had significantly greater mean marginal bone loss (−1.77mm ± 0.18, mean ± SE) than machined (−0.85mm ± 0.18, p < .001) and microtextured (−1.00 ± 0.18mm, p < .001) implants with the shorter machined collar. Keratinized tissue height was greater for internal‐connection (0.74mm ± 0.10) versus external‐connection (0.51 ± 0.08, p =  0.01) microtextured implants. No differences were observed for plaque (p = 0.78), probing depth (p = 0.42), bleeding (p  = 0.07), and purulence (p = 1.00). Implant survival rate was 99%. Conclusions Implants with the 1.2mm machined collar limited bone loss to 1mm, while those with the longer machined collar showed > 1.5mm loss after 25 years of function with microgap at the crest. Internal‐connection design and fixture surface microtexturing did not result in greater bone preservation. ClinicalTrials.gov Identifier: NCT03862482.

Sémiotiques 1 : mises au point, mises en question Volume 1, numéro 1, automne 1990 URI : id.erudit.org/iderudit/800856ar

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