A risk assessment treatment planning protocol for the four implant immediately loaded maxilla: preliminary findings

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Statement of problem.

There is debate as to the efficacy of maxillary complete arch reconstructions when only 4 implants are used.


The purpose of this study was to determine what risk factors, if any, may increase the likelihood for implant failure in immediate function by using a tilted distal, 4-implant approach in the maxilla.

Material and methods.

A retrospective analysis of implant performance was conducted for patients treated with 4 implants placed in 285 maxillae (1140 implants) and 273 mandibles (992 implants) providing immediate function for complete arch implant-supported prostheses. The consecutively treated patient cohort consisted of those who provided consent between April 2008 and December 2010. A retrospective chart review was conducted to assess potential maxillary implant failure factors, including a history of smoking, gender, opposing occlusion, bone density, bone volume, insertion torque, parafunction, failed implant site, addiction, and systemic factors. Data were analyzed with descriptive statistics. A series of risk factors were postulated in an effort to establish guidelines for modification of treatment planning protocols in response to combined risks.


Several common primary factors in maxillary implant failure scenarios were identified through this process of patient profiling. Opposing natural dentition, male gender, lack of bone density, the distal implant site, and parafunction were sufficiently frequent occurrences in failure situations to suggest that either the use of additional implants or delayed loading and the provision of a complete denture as an interim prosthesis may be more appropriate in the management of patients identified as being high risk. Secondary factors such as bone availability (volume) and smoking were less common in failure situations.


A preliminary protocol is suggested for both treatment planning and profiling patients with respect to presenting characteristics that may contribute to implant failure. A decrease in failure occurrence has been noted anecdotally during the short term implementation of this protocol.

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