Early crestal bone loss: Is it really loss?

Abstract Bone remineralization around dental implants might be possible after early crestal bone loss.


| CLINICAL CASES
In this article, we are going to present you 3 different clinical cases of early crestal bone loss and bone remineralization.

| Case 1
Bone level (Biohorizons) implant was placed at the site of #46 tooth simultaneously with healing abutment. After 3 months of osseointegration ( Figure 1A), metal ceramic crown was placed with a regular platform ( Figure 1B). During regular checkup, bone remineralization around dental implant #46 is visible together with stable crestal bone ( Figure 1C).

| Case 2
Another clinical case shows similar postop result. Bone level (Biohorizons) dental implant was placed nonsubmerged. Periapical X-ray before prosthetic treatment shows early crestal bone loss (Figure 2A). After implant loading with a metal ceramic crown and regular platform, bone remains similar with previous observations ( Figure 2B). Two years later, periapical radiograph was made and it shows bone remineralization at the site #36 ( Figure 2C). Crestal bone contour is stable.

| Case 3
Third clinical case: Patient came to the clinic for the implant placement at the site #36. Bone level (Straumann) dental implant was placed, and healing abutment was screwed at the same surgery. Three months later, periapical X-ray reveals pleasant results but still early crestal bone loss is visible ( Figure 3A). During prosthetic treatment, implant was loaded with metal ceramic crown and platform switching ( Figure 3B). Two years later, a regular checkup and new periapical X-ray were made. It is seen that bone remineralization occurred also in this case with a stable crestal bone around implant neck ( Figure 3C).

| DISCUSSION
Three similar cases were showed with visible crestal bone loss and following remineralization process around dental implants. With this in mind, it can be presumed that not always crestal bone loss is real bone resorption of the bone tissue. In some cases, only demineralization of crestal bone happens, looking like a bone loss in periapical X-ray.
Demineralization is the process caused by inflammation when mineral ions of hydroxyapatite (HA) removed from the hard tissues, particularly in the bone. 2 Even though HA is one of the most stable calcium phosphate salt, 3 the inflammation process might lead to the bone matrix changes following bone loss. Inflammation is related with the overproduction of various cytokines and bone cells. 4 They initiate hyperactivation of osteoclasts and lead to the bone degradation; also, some cytokines negatively affect osteoblast function. 5 Remineralization might be achieved by increasing osteoblasts function; particularly, these cells promote crystal formation of hydroxyapatite, propagate growth in the interior part of membrane-limited matrix vesicles, 6 and induce crystals in the collagenous extracellular matrix thus mineralizing bone matrix overall. 7 There are many factors influencing early crestal bone loss. The most important are platform switching, polished implant neck, stable connection, and sufficient vertical soft tissue thickness around implant neck. 8 Paying attention to these factors, it seems possible to have a huge potential for zero bone loss or even bone remineralization, if it happens. Previous option is already seen in our clinical practice.
As a weakness of this statement could be mentioned accuracy of periapical X-rays, the state of being parallel and equally angulated.
Bone remineralization may occur around dental implants with a history of early crestal bone loss after loading. There is still considerable uncertainty of exact histological