**1. Introduction**

In contemporary implant prosthodontics, proper treatment planning prior to dental implant placement is equally important as the prosthetic factors. The good work of oral surgeon could be easily ruined by poor prosthodontic execution, thus changing the dental implant therapy success into therapy failure.

For decades, the scientific literature identified the following criteria for the survival and success of dental implant-based prosthetic rehabilitation:

	- Implant placed in situ and loaded; no chronic discomfort; no nerve lesion; no peri-implant infection with suppuration; no mobility; no continuous periimplant radiolucency [1, 3].

• No probing depth greater than 5 mm in the presence of a bleeding index of 3 [4].

Absence of radiographic peri-implant bone resorption greater than 1.5 mm in the first year of function [2] and greater than 0.2 mm in subsequent years (i.e. 1.7 mm after 2 years); alternative cut-off values for radiographic bone resorption after 2 years of 2 mm (I. Success) and 4 mm (II. Satisfactory Survival) were also evaluated [5].

Currently, implant success is defined by these three criteria [6]:


These criteria are based on older studies, previous dental implant designs and restorations that are not biocompatible, and they might need to be re-evaluated. Porcelain fused to metal (PFM) restorations lack the biocompatibility of zirconia, which is widely used today, and current concepts allow bone stability or even growth over time. Therefore, the expected 1.5 mm loss after 1 year and subsequent gradual resorption can be considered relicts of the past [6].
