HISTOLOGICAL COMPARISON OF THE BIOLOGIC WIDTH BW IMPLANTS TEETH effect of bone preservation MTO IMPORT makigusa

 

 

 

Histological analysis of the biological width surrounding primate teeth offers insights into why the blood supply is reduced after tooth extraction and implant placement. This occurs because of the reduction of ridge width and height. The reduction in blood supply tends to be exacerbated as development of a new biologic width after implant placement causes facial bone to be lost both vertically and horizontally. 

 

 

In the human body, ectodermal tissue serves to protect against invasion from bacteria and other foreign materials. However, both teeth and dental implants must penetrate this defensive barrier. The natural seal that develops around both, protecting the alveolar bone from infection and disease, is known as the biologic width. Around natural teeth, the biologic width has been shown to consist of approximately 1mm of connective tissue, 1mm of epithelium, and 1mm or more of sulcular depth (Figure 1).1 

The biologic width that develops around implants at the time of abutment connection has been demonstrated to incorporate tissue zones of similar dimensions.2 

However, Figures 2 and 3 demonstrate some morphologic differences in the distribution of the vascular network.

 

To assess the microvasculature of the biologic width in primates, the author worked with Japanese snow monkeys (Macaca fuscata), whose masticatory function and mandibular morphology closely resembles that of humans.4 

A premolar tooth was extracted and clear morphological differences were observed between the gingival area of the alveolus, the alveolar mucosa, and the body of the mandible. 

Furthermore, three different blood supply routes to the gingival connective tissue attachment site were identified. 

 

MUITO IMPORTANTE

The origins of these blood supply routes are as follows:

from the periodontal ligament to the connective tissue,

from the alveolar process to the periodontal ligament and then to the connective tissue,

and from the alveolar process directly to the connective tissue (Figure 4).

 

 

Figure 5: Illustration depicting the inherent thinning of the ridge

following the development of the biologic width around standard

two-stage implants. Note the increase in cortical bone and the

reduction in cancellous bone.

 

When implants replace teeth the overall blood supply to the gingival connective tissue is reduced,

due to the absence of a periodontal ligament.

 

This has

important implications for clinicians considering placement

of implants, particularly in the aesthetic zone, where

recession of buccal gingival tissue is a common

occurrence.5,6

 

 

The thicker the native hard and soft tissue, the more

abundant the blood supply that can be expected after

iimplant placement, with correspondingly heightened

expectations for aesthetic success.

 

Besides the absence of the periodontal ligament, blood

supply around dental implants is less than that around

natural dentition as the result of a dynamic process of bone

remodeling.

 

After implant placement, the biological width

must be reestablished & ON ABUTMENT´S IMPLANT CONNECTION.

As this occurs, circumferential bone loss typically occurs around the implant’s coronal aspect up

to the first implant thread (Figure 5).

Also, resorption in a palatal direction following tooth loss results in ridge thinning.

The thin bone remaining on the facial aspect of the implant tends to be cortical, with significantly less vascularity.

 

Furthermore, in a thin ridge, there is rapid drop

off (sloping) of the buccal aspect of the crest, resulting in

more of the blood supply being positioned apically, where

the bone crest is wider and more cancellous (Figure 6).

 

 

 

The microgap that occurs at the junction of the implant

and abutment in traditional two-stage implant systems has

been implicated as a cause of the vertical and horizontal

bone loss occurring after abutment connection.7

Bacterial

contamination of this microgap has been associated with

formation of an inflammatory cell infiltrate8,9 that, in turn,

may trigger circumferential bone resorption.

 

 

In theory, if bone is

preserved, it will support soft tissue that may impact the

aesthetic outcome. Greater bone volume can also increase

blood supply for the health and maintenance of soft tissues

(Figure 7).

For this reason, candidates with thick biotypes are

better candidates for implants in the aesthetic zone.

 

FIGURA 10 NÃO ESTÁ NO MESMO NÍVEL QUE FIGURA 9 NO CENTRO DO IMPLANTE