A 5‐year longitudinal cohort study on crown to implant ratio effect on marginal bone level in single implants

Abstract

Background A 5‐year longitudinal cohort study was carried out to evaluate the influence of anatomical crown to implant ratio (CIR) on peri‐implant marginal bone level (MBL) in single implants. Materials and Methods The longest possible implants, according to the availability of pristine bone, were inserted, one per patient, among periodontally healthy teeth in consecutively recruited subjects. CIR and MBL changes were measured on standardized radiographs. The relationship between MBL and multiple predictors was investigated. A statistical analysis suitable for mixed type distributions was conducted: for the discrete component a logistic regression model was used and for the continuous component the impact of the variables on MBL was examined by using robust nonparametric comparison tests. Results Seventy‐eight dental implants were inserted in 34 mandibles and 44 maxillae, with one stage procedure in 40 cases and two stage in 38 cases. Thirty‐five implants were <10 mm, while 43 were ≥ 10 mm long; 28 implants had a CIR ≤1 and 50 had a CIR >1. No drop‐outs or implant loss were observed. Bone loss occurred only in a few cases, measuring less than 0.5 mm and being significantly more pronounced for implant length ≥10 mm, for lower CIR values and for the two stage procedure. Conclusion Higher CIR values were not related to increased peri‐implant bone loss; a <10 mm long implant insertion may be safely considered for reduced bone heights.

Horizontal Ridge Augmentation and Contextual Implant Placement with a Resorbable Membrane and Particulated Anorganic Bovine Bone-Derived Mineral

“…Horizontal ridge augmentation has been illustrated using a variety of different techniques and materials [29]. In the case in question, we used a resorbable collagen membrane so as to avoid some of the drawbacks when using nonresorbable membranes, like the necessity for a second surgical procedure to remove the membrane combined with the risk of losing more of the regenerated bone due to flap reflection [30]. Moreover, the conclusion of an in vitro study which compared resorbable and nonresorbable membranes was that bioabsorbable membranes, particularly collagen and hyaluronic acid, may promote bone regeneration through their activity on osteoblasts which suggests that bioabsorbable membranes could be more apt than nonresorbable membranes because they encourage the regeneration and repair of bones [31].…”

Effect of crown-to-implant ratio and crown height space on marginal bone stress: a finite element analysis

“…It is also in line with the studies from Sutpideler et al [10] who found that the stresses were increased when the height of the prostheses increased, regardless of the angle of the applied force or the amount of offset. A study from Ramaglia et al [36] had already suggested that the marginal bone loss was neither influenced by the implants' length nor by the CIR.…”

“…Blanes [8], Okada et al [34] and Esfahrood et al [35] stated that the CIR does not influence the marginal bone maintenance. A longitudinal cohort study conducted by Ramaglia et al [36] suggested that bone loss is neither related to implant length nor to anatomical CIR. An in vitro experiment published by Nissan et al [37] reported that a different factor, the crown height space (CHS), would be more significant than CIR in assessing biomechanical-related detrimental effects, recommending vertical bone augmentation procedures when the CHS is 15 mm or longer [38].…”

Principles of biomechanics in oral implantology

“…Recent studies seem to only partially agree with this theory. A 5-year longitudinal cohort study published in 2019 [36] states that higher CIR values do not necessarily induce peri-implant bone loss and that using short implants may always be considered as an option in reduced bone heights. Other studies also state that increasing the CIR does not have significant effect on marginal bone loss [37][38][39][40].…”