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Implantology

Authors Dr. Prerna Kaushik

Dental Implants is now a mainstream protocol in aesthetic and restorative dentistry. Bone and soft tissue around the implant constantly remodels, which is attributed to numerous factors. Most important of all being the “concept of establishing the biologic seal or Biologic Width”, this may be considered as a 3-D zone representing the body’s defense mechanism to seal the implant abutment interface, which is further influenced by the thickness of soft tissues. (Tidu Mankoo)

Seibert and Lindhe (1989) coined the term periodontal biotype to describe different gingival architecture types based on bucco-lingual thickness.
 
  1. Thin scalloped type periodontium
  2. Thick flat type periodontium

In implant dentistry the peri-implant mucosa has been differentiated in thick, medium and thin tissue biotype .
 
Table-1 Techniques for measuring soft tissue thickness:-
 

TECHNIQUE

ADVANTAGE

DISADVANTAGE

Visual inspection

Simple, straight forward, non-invasive and inexpensive

Subjective and highly variable

Transgingival probing

Simple, straightforward and inexpensive

Invasive- requires local anesthesia and affected by probe diameter, angulation, probing force and distortion of gingival tissues.

Probe transparency

Simple, straightforward and inexpensive

Subjective and invasive

Ultrasonic device

Simple, straightforward and inexpensive

Additional cost involved, large probe diameter may hinder its use in areas of limited access, accuracy might be affected by moisture

CBCT imaging

Non-invasive, can provide quantitative measurements, images can be manipulated for better visualization of the hard and soft tissues.

Expensive, requires technical expertise, and higher radiation exposure compared to conventional tomography.


Evans and Chen defined biotype by probe transparency,to check for the biotype, a UNC periodontal probe was to be inserted into the gingival sulcus of the facial tooth surface. If the probe is not visible through the facial gingival, a thick biotype will be assigned. If only the black color of the probe markings are visible, a moderate biotype will be assigned. If the millimeter markings on the probe are completely visible through the tissues the biotype will be designated as thin.
Each biotype has its specific characteristics:-
The lower risk is posed by a thick, broad band of attached mucosa, typically resistant to recession. The thick mucosa is able to mask the color of the implant and their submucosal metallic component, reducing the risk of not achieving a pleasing esthetic result. Martin et al
In contrast, a thin tissue biotype have the highest esthetic risk of mucosal recession.
A recent study by Nisapakultorn et al. found that peri-implant tissue biotype was significantly associated with facial marginal mucosal level. Also, patients with a thin biotype had less papilla fill and an increased risk of peri-implant facial mucosal recession.
 
Table-2 CHARACTERISTICS OF THIN AND THICK TISSUE BIOTYPES;-
 

CHARACTERISTICS

THIN

THICK

Profile

Highly scalloped

Relatively flat soft tissue and bone contours

Soft tissue texture

Delicate and friable

Dense and fibrotic

Width of keratinized and attached gingival

Narrow

Wide

Bone thickness

Thin with bony dehiscences and fenestrations

Thick with ledges

Reaction to insults

Reacts readily with gingival recession

Relatively resistant to gingival recession, reacts with formation of pocket or infrabony defect.


TOOTH MORPHOLOGY IN RELATION TO THE PERIODONTAL BIOTYPE

Tooth morphology is related to the periodontal biotype, and this phenomenon is most evident in the anterior esthetic zone of the mouth. The triangular shaped tooth is linked to a thin, scalloped periodontium (Biotype I) (Ochsenbein et al). In this biotype, the interproximal contact area is located in the coronal one-third of the crown and is associated with a long, thin papilla. The square-shaped tooth is connected to a thick, flat periodontium(Biotype II) (Ochsenbein et al) The interproximal contact area is located at the middle one-third of the crown and supports a short, wide papilla.( Ochsenbein et al, Olsson et al.)

According to Pallaci et al. gingival thickness, the morphology of the gingiva and the interdental papilla, and the osseous architecture are all determining factors in periodontal biotyping and can influence surgical approaches and healing . Ochsenbein & Ross described healthy periodontal tissues by the biotype categories of 1. thin scalloped- (thin gingival tissue, long papillae, and thin, scalloped bone) and 2. thick flat- (thick gingival tissue, short and wide papillae, and thick, flat bone).

Olsson & Lindhe further categorized the periodontium based on the associated tooth form and susceptibility to gingival recession. The triangular tooth form is associated with a scalloped and thin periodontium. The contact area for the triangular tooth shape is at the coronal third of the crown, supporting a long and thin papilla. The squared tooth combines with a thick and flat periodontium. The contact area for the square tooth shape is at the middle third of the crown, supporting a short and wide papilla.

Periodontal biotyping affects practically all periodontal surgical procedures, including crown lengthening, implant placement and tissue grafting. A thin periodontal biotype is the more technique-sensitive and may lead to gingival recession or black triangle formation. An implant placed in a site with a thin periodontal biotype may develop mucosal recession or bluish color changes.
 
Table 3- FATT criteria for immediate implant placement:- ( Bach Le)
 

FATT

Favorable

Unfavorable

Favorable gingival level

Free gingival margin >1mm coronal to anticipated level.

Free gingival margin at or apical to anticipated level.

Attachment on adjacent tooth

<5mm from anticipated contact point

>5mm from anticipated contact point

Thick / Thin biotype

No translucency on probing

Probe visible through gingival

Thick / Thin labial bone

>1mm residual labial bone

<1mm residual labial bone

 
Table 4- TISSUE BIOTYPES (Bach Le)
 

 

Periodontium

Tooth shape

Band of keratinized tissue

Associated gender

Thin biotype

Scalloped

Slender

Thin

Female

Thick biotype

Blunted

Square

Thick

Male


A thick biotype will have a large amount of attached keratinized gingival with greater resistance to traumatic or inflammatory recession, however a thin biotype is susceptible to recession induced by resorption of thin labial cortical plate. Thus, biotype conversion by increasing the quality and quantity of the facial gingival tissue with SCTG(Sub-epithelial Connective Tissue Graft) might be beneficial for facial gingival stability. Saadoun et al Certain studies attempted to correlate tissue thickness and crestal bone stability.
It was observed that within the first year of function , a maximum of 1.45 mm of crestal bone loss was associated with an initial tissue thickness of < 2.5 mm (thin biotype). Reported 1.8mm of marginal mucosal recession in thin-biotypes compared to 0.6mm in thick biotypes. A thick biotype is important since they have increased blood supply that will enhance the revascularization of bone grafts, leading to increased healing and graft incorporation. Thin biotypes actually compromise the collateral blood supply to the surgical site. Another advantage of a thick biotype is the ability to attain and maintain primary wound closure.

REVIEW OF LITERATURE:-

Olsson and Lindhe (1991) referred to these as periodontal biotypes and found the "thick flat" periodontal biotype to be more prevalent than the "scalloped thin" form (85 % to 15 %). The contour and form of the gingiva is closely followed the contour of the underlying bone. The stability of the osseous crest and position of the free gingival margin are directly proportional to the thickness of the bone and gingival tissues.

Kan et al. (2003b) measured the peri-implant mucosal dimensions of 45 implants placed in the maxillary anterior. Peri-implant biotypes were also evaluated and categorized as thick and thin. He concluded that the level of the interproximal papilla is independent of the proximal bone level next to the implant, but is related to the interproximal bone level next to the adjacent teeth. The papilla heights between thick and thin biotypes were compared after 1 year of function and reported .
Table 3 Papilla Height Relative to Periodontal Biotype
 

 

                                                            Mesial                                                 Distal

Mean Papilla Height                           4.2mm                                                 4.2 mm

Thick Biotype                                                 4.5mm                                                 4.5mm

Thin Biotype                                       3.8mm                                                 3.8mm


Kan et al. (2009) conducted a study in which 20 consecutive patients who had undergone immediate single tooth replacement with connective tissue grafting, soft tissue changes and biotypes were evaluated. At a mean follow-up of 2.15 years, 100% of the sites had 2: 50% papilla fill while 80% of the sites had complete papilla fill, validating the efficacy of immediate tooth replacement in preserving the interproximal papilla. In addition, patients exhibited thick biotype morphology. However, no significant differences were observed between the initially thin or thick gingival biotypes when comparing changes in mean facial gingival levels.

Kan et al. 2011, showed that sites with thick gingival biotypes exhibited significantly smaller changes in facial gingival levels than sites with thin gingival biotypes at 1 year after placement (-0.25 mm versus -0.75 mm respectively) and at the 4 year follow up (-0.56 mm and -1.50 mm respectively).

Kim et al. (2011) showed that sites with thicker gingival biotypes exhibited statistically significantly smaller changes in facial gingival levels than sites with thinner gingival biotypes at 1 year after placement.
REFERENCES:-
  1. Tidu Mankoo. Maintenance of interdental papillae in the esthetic zone using multiple immediate adjacent implants to restore failing teeth- a report of Ten cases at 2 to 7 years follow-up. The European Journal of Esthetic Dentistry. Vol. 3 No. 4 Winter 2008
  2. Seibert J , Lindhe J . Esthetics and periodontal therapy . Textbook of clinical periodontology .ed 2 . Copenaghen : Munksgaard ; 1989 . p. 477 - 514 .
  3. Jia-hui Fu, Angle Lee. Influence of tissue biotype on implant esthetics. Int J. Oral and Maxillofac Implants. 2011;26:499-508.
  4. Martin W C , Morton D , Buser D . Diagnostic factors for esthetic risk assessment . ITI Treatment Guide, Vol I: Implant therapy in the esthetic zone: single-tooth replacements . Berlin : Quintessence ; 2007 . p. 11 - 20 .
  5. Nisapakultorn K , Suphanantachat S , Silkosessak O , Rattanamongkolgul S . Factors affecting soft tissue level around anterior maxillary single-tooth implants . Clin Oral Implants Res 2010 ; 21 : 662 - 70 .
  6. Ochsenbein C, Ross S. A concept of osseous surgery and its clinical applications. Charles C. Thomas Publishing, Co., 1973: 276–322.
  7. Olsson M, Lindhe J. Periodontal characteristics in individuals with varying forms of the upper central incisors. J Clin Periodontol 1991: 18: 78–82.
  8. Park LE. Appearance-based rejection sensitivity: implications for mental and physical health, affect, and motivation. Pers Soc Psychol Bull 2007: 33: 490–504.
  9. Pontoriero R, Carnevale G. Surgical crown lengthening: a12-month clinical wound healing study. J Periodontol 2001:72: 841–848.
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