Chương 3 Mô mềm quanh răng và Implants Jan Lindhe, Jan L. Wennström, and Tord Berglundh


Fig. 3-10 Radiograph obtained from the premolars in the left side of the mandible. Fig. 3-11



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Fig. 3-10 Radiograph obtained from the premolars in the left

side of the mandible.



Fig. 3-11 Radiograph obtained from the implants in the right

side of the mandible.

was observed that the alveolar bone crest was located

about 1 mm apical of a line connecting the cemento-

enamel junction of neighboring premolars (Fig. 3-10).

The radiographs from the implant sites disclosed that

the bone crest was close to the junction between the

abutment and the fixture part of the implant (Fig.

3-11).

Histological examination of the sections revealed



that the two soft tissue units, the gingiva and the

peri-implant mucosa, had several features in common.

The oral epithelium of the gingiva was well keratin-

ized and continuous with the thin junctional epithe-



The Mucosa at Teeth and Implants

Fig. 3-12 Microphotograph of a cross section of the buccal

and coronal part of the periodontium of a mandibular

premolar. Note the position of the soft tissue margin (top

arrow), the apical cells of the junctional epithelium (center

arrow) and the crest of the alveolar bone (bottom arrow).

The junctional epithelium is about 2 mm long and the

supracrestal connective tissue portion about 1 mm high.

73

lium that faced the enamel and that ended at the

cemento-enamel junction (Fig. 3-12). The supra-

alveolar connective tissue was about 1 mm high and

the periodontal ligament about 0.2–0.3 mm wide. The

principal fibers were observed to extend from the

root cementum in a fan-shaped pattern into the soft

and hard tissues of the marginal periodontium (Fig.

3-13).


The outer surface of the peri-implant mucosa was

also covered by a keratinized oral epithelium, which

in the marginal border connected with a thin barrier

epithelium (similar to the junctional epithelium at the

teeth) that faced the abutment part of the implant

(Fig. 3-14). It was observed that the barrier epithe-

lium was only a few cell layers thick (Fig. 3-15) and
Fig. 3-13 Higher magnification of the supracrestal connective

tissue portion seen in Fig. 3-12. Note the direction of the

principal fibers (arrows).

that the epithelial structure terminated about 2 mm

apical of the soft tissue margin (Fig. 3-14) and 1–

1.5 mm from the bone crest. The connective tissue in

the compartment above the bone appeared to be in

direct contact with the surface (TiO2) of the implant

(Figs. 3-14, 3-15, 3-16). The collagen fibers in this con-

nective tissue apparently originated from the perios-

teum of the bone crest and extend towards the margin

of the soft tissue in directions parallel to the surface



of the abutment.















74

Anatomy


Fig. 3-16 Microphotograph of a section (buccal–lingual) of

the implant–connective tissue interface of the peri-implant

mucosa. The collagen fibers invest in the periosteum of the

bone and project in directions parallel to the implant surface

towards the margin of the soft tissue.

Fig. 3-14 Microphotograph of a buccal–lingual section of the

peri-implant mucosa. Note the position of the soft tissue

margin (top arrow), the apical cells of the junctional

epithelium (center arrow), and the crest of the marginal bone

(bottom arrow). The junctional epithelium is about 2 mm

long and the implant–connective tissue interface about

1.5 mm high.

Fig. 3-17 Implants of three systems installed in the mandible

of a beagle dog. Astra Tech Implants® Dental System (left),

Brånemark System® (center) and ITI® Dental Implant System

(right).

The observation that the barrier epithelium of the

healthy mucosa consistently ended at a certain dis-

tance (1–1.5 mm) from the bone is important. During

healing following implant installation surgery, fibro-

blasts of the connective tissue of the mucosa appar-

ently formed a biological attachment to the TiO2 layer

of the “apical” portion of the abutment portion of the

implant. This attachment zone was evidently not rec-

ognized as a wound and was therefore not covered

with an epithelial lining.

In further dog experiments (Abrahamsson et al.

1996, 2002) it was observed that a similar mucosal

attachment formed when different types of implant

systems were used (e.g. Astra Tech Implant System,



Fig. 3-15 Higher magnification of the apical portion of the

barrier epithelium (arrow) in Fig. 3-14.



Astra Tech Dental, Mölndal, Sweden; Brånemark

System®, Nobel Biocare, Göteborg, Sweden; Strau-















The Mucosa at Teeth and Implants

75



a

b

c

Fig. 3-18 Microphotographs illustrating the mucosa (buccal–lingual view) facing the three implant systems. (a) Astra. (b)

Brånemark. (c) ITI.


mann® Dental Implant System, Straumann AG, Basel,

Switzerland; 3i® Implant System, Implant Innovation

Inc., West Palm Beach, FL, USA). In addition, the

formation of the attachment appeared to be indepen-

dent of whether the implants were initially sub-


Flap adaptation and suturing

OE

OE


merged or not (Figs. 3-17, 3-18).

In another study (Abrahamsson et al. 1998), it was

demonstrated that the material used in the abutment

part of the implant was of decisive importance for the

location of the connective tissue portion of the trans-

mucosal attachment. Abutments made of aluminum-

Test

B

2 mm



Control

B

4 mm
based sintered ceramic (Al2O3) allowed for the

establishment of a mucosal attachment similar to that

which occurred at titanium abutments. Abutments

made of a gold alloy or dental porcelain, however,

provided conditions for inferior mucosal healing.

When such materials were used, the connective tissue

attachment failed to develop at the abutment level.

Instead, the connective tissue attachment occurred in

a more apical location. Thus, during healing follow-

ing the abutment connection surgery, some resorp-

tion of the marginal peri-implant bone took place to

expose the titanium portion of the fixture (Brånemark

System®) to which the connective tissue attachment

was eventually formed.

The location and dimensions of the transmucosal

attachment were examined in a dog experiment by

Berglundh and Lindhe (1996). Implants (fixtures) of

the Brånemark System® were installed in edentulous

premolar sites and submerged. After 3 months of

healing, abutment connection was performed. In the

left side of the mandible the volume of the ridge

mucosa was maintained while in the right side the

vertical dimension of the mucosa was reduced to

≤2 mm (Fig. 3.19) before the flaps were replaced and

sutured. In biopsy specimens obtained after another

6 months, it was observed that the transmucosal


Fig. 3-19 Schematic drawing illustrating that the mucosa at

the test site was reduced to about 2 mm. From Berglundh &

Lindhe (1996).

attachment at all implants included one barrier epi-

thelium that was about 2 mm long and one zone of

connective tissue attachment that was about 1.3–

1.8 mm high.

A further examination disclosed that at sites

with a thin mucosa, wound healing consistently

had included marginal bone resorption to establish

space for a mucosa that eventually could harbor

both the epithelial and the connective tissue compo-

nents of the transmucosal attachment (Figs. 3-20,

3-21).


The dimensions of the epithelial and connective

tissue components of the transmucosal attachment at

implants are established during wound healing fol-

lowing implant surgery. As is the case for bone

healing after implant placement (see Chapter 5), the

wound healing in the mucosa around implants is a



delicate process that requires several weeks of tissue

remodeling.









76

Anatomy

In a recent animal experiment, Berglundh et al.

(2007) described the morphogenesis of the mucosa

attachment to implants made of c.p. titanium. A non-

submerged implant installation technique was used

and the mucosal tissues were secured to the conical

marginal portion of the implants (Straumann® Dental

Implant System) with interrupted sutures. The

sutures were removed after 2 weeks and a plaque-

control program was initiated. Biopsies were per-

formed at various intervals to provide healing periods

extending from day 0 (2 hours) to 12 weeks. It was

reported that large numbers of neutrophils infiltrated

and degraded the coagulum that occupied the com-

partment between the mucosa and the implant during

6 months


PM

the initial phase of healing. The first signs of epithe-

lial proliferation were observed in specimens repre-

senting 1–2 weeks of healing and a mature barrier

epithelium was seen after 6–8 weeks. It was also

demonstrated that the collagen fibers of the mucosa

were organized after 4–6 weeks of healing. Thus,

prior to this time interval, the connective tissue is not

properly arranged.

Conclusion

The junctional and barrier epithelia are about 2 mm

long and the zones of supra-alveolar connective

tissue are between 1 and 1.5 mm high. Both epithelia

are attached via hemi-desmosomes to the tooth/

implant surface (Gould et al. 1984). The main attach-

ment fibers (the principal fibers) invest in the root

cementum of the tooth, but at the implant site the

equivalent fibers run in a direction parallel with the

implant and fail to attach to the metal body. The soft

tissue attachment to implants is properly established

PM
aJE




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