Nasal Wall Oriented Implants for All-on-4 Fix-Detachable Maxillary Reconstruction

Immediate loading of full-arch prostheses on dental implants in the upper arch is challenging, as the bone is of low quality and obtaining sufficient torque may be difficult. The purpose of this case report is to describe the rehabilitation of a full-arch by means of placement of four internal tapered connection tilted implants and immediate loading. A 65-year-old man sought dental care with a partially edentulous upper arch. The teeth presented mobility and were extracted. In a second step, two conventional-length implants were placed in the anterior region and two tilted and nasal wall–directed extra-long implants in the posterior region. The insertion torques of 60 N.cm allowed the installation of an immediate prosthesis (hybrid). The clinical case report suggests that the placement of tilted and extra-long implants in the paranasal bone and immediate loading may be a viable option for rehabilitation of the edentulous upper arch.

Microbiological Sealing Analysis of a Tapered Connection and External Hexagon System

Considering the variety of implant connection systems available in the market and the contrasting literature regarding tapered connection systems in terms of bacterial leakage, the aim of this in vitro study was to compare the effectiveness of the bacterial seal at the implant/abutment interface between an external hexagon and a tapered connection system. Twelve sets of indexed tapered connection components and twelve sets of external hexagon connection components were used for microbiological analysis. In addition, for each model, an implant with its respective prosthetic abutment was used as a negative control and another as a positive control of microbial contamination. Failure of the abutment/implant interface seal was observed via turbidity or presence of deposits in the culture. Descriptive analysis of the data and relative frequency (percentage) as well as Fisher’s exact test were used at a significance level of 5%. Two of ten (20%) external hexagon specimens showed contamination against 0/10 (0%) tapered connection implants. In conclusion, both implant/abutment connections were able to prevent bacterial leakage in vitro.

The Effect of a Positioning Index on the Biomechanical Stability of Tapered Implant-Abutment Connections

The biomechanical stability of the implant-abutment connection is critical for the success of implant-supported restorations. This study investigated the effect of a positioning index on the abutment screw preload values of tapered connection implants. Twenty Morse taper implants presenting an internal locking hex received 10 solid and 10 straight screw retained abutments for cemented single-crown restorations. Ten abutments had a positioning index to fit the internal locking hex of the implant (straight), and 10 were locked only by the implant taper (solid). The preload values for each abutment screw after a tightening torque were registered by strain gauges. Prosthetic crowns were placed on each abutment and subjected to mechanical cycling. Detorque forces were applied to each abutment and compared with the initial torque values. Data were statistically analyzed using Kolmogorov-Smirnov and Student t tests. The nonindexed group presented higher initial preload (6.05 N ± 0.95 N) compared with the indexed group (4.88 N ± 0.92 N; P < .05). After cycling, the nonindexed group exhibited less reduction of preload (13.84% ± 6.43%) compared with the indexed group (52.65% ± 14.81%; P < .01). Indexed tapered abutments for single-crown restorations might represent greater biomechanical risk under function.