CBCT is of course more accurate as most of the researches proved that there were no significant differences between CBCT measurements and reality and some authors said that even these differences are not clinically significant
CBCT can definitely provide adequate information related to alveolar ridge resorption; however, it also includes a cost factor and exposure to ionizing radiation for the patient. A very simple way to determine bone width will be by using an endo file and invasively puncturing the soft tissue (under local anesthesia both buccally and lingually/palatally) until bony resistance is felt. This will provide a measure of the soft tissue which can then be deducted from the ridge width to obtain bone thickness. This technique is also sometimes known as "bone sounding". The only drawback I see with this is that it is invasive, albeit nothing more than an injection prick. The several advantages include their relatively inexpensive technique, no need for radiation exposure, and the ability to obtain instant information that is clinically relevant.
Dear Alberto, it is a fact that, at the state of knowledge, the absence of an universally accepted measurement method, able to assess the degree of defect correction and the three-dimensional stability over time of the augmented bone, still prevent clinicians to draw significant conclusions about the long-term clinical success of the different augmentation procedures.
Of course, neither open flap caliper measurements nor CT scan can be considered feasible routine methods of monitoring bone stability over time, because of their unreasonable economical and biological costs.
I fully agree with Dr Kashi that “bone sounding” is the technique with the best cost-benefit ratio, but - as rightly pointed out Dr Nakamai about the angulation of the caliper- the reproducibility of position may be an issue, for any chosen instrument for measuring . This problem - for bone sounding - may be partly overcome by using a template customized on the basis of final restoration and pierced at some buccal and lingual/palatal points at each implant site. In this way the holes guide the endo files during bone sounding in a reproducible position and angle, allowing the long-term evaluation of the horizontal stability of the augmented bone.
In this regard, if you think it might worthwhile, please view the article
Horizontal and vertical ridge augmentation in localized alveolar deficient sites: a retrospective case series. Implant dentistry. 06/2012; 21(3):175-85
available at : https://www.researchgate.net/publication/225054009_Horizontal_and_vertical_ridge_augmentation_in_localized_alveolar_deficient_sites_a_retrospective_case_series
Article Horizontal and Vertical Ridge Augmentation in Localized Alve...