CHAPTER 11: HOST MODULATION & IMPLANT THERAPY

Host Modulation Therapy (HMT)

Used in addition to scaling and root planing (SP) and surgery.

Modifies or reduces destructive aspects and upregulates protective aspects of the host response

Adjunctive approach to conventional periodontal therapy targeting the patient’s immune-inflammatory response, which drives tissue breakdown

purpose of Host Modulation Therapy (HMT)

aims to reduce excessive inflammation

enhance wound healing

periodontal stability

Risk Factors of Host Modulation Therapy (HMT)

Addresses factors that adversely affect host response (e.g., smoking, diabetes, genetic susceptibility)

addresses the host side of the host-bacterial interaction, ameliorates excessive inflammatory processes to enhance wound healing and periodontal stability

drug classes that evaluated as HMTs:

NSAIDs

bisphosphonates

tetracyclines

enamel matrix proteins

growth factors

BMPs

comprehensive management of host modulation therapy

patient education

bacterial reduction (SP)

site-specific antibacterial treatment

risk factor modification

surgery if needed.

Host Modulation Therapy (HMT) Agents

NSAIDs

Bisphosphonates

sub-antimicrobial-dose doxycycline (SDD)

NSAIDs

Systemic use can significantly slow alveolar bone loss.

Inhibit Prostaglandin E2 (PGE2), which upregulates bone resorption

Stopping it may cause a “rebound effect” with accelerated bone loss

Not indicated as adjunctive HMT due to serious side effects and the need for long-term daily use.

risk of NSAIDs

GI problems

hemorrhage

higher fragility of bone

—due to daily use for up to 3 years showed benefits however these can be an effect

Bisphosphonates

inhibits osteoclast activity, shown to enhance alveolar bone status in studies.

bone-seeking agents that inhibit bone resorption by disrupting osteoclast activity.

not approved for periodontal disease; discouraged due to risk primarily with intravenous use

risk of bisphosphonates

osteonecrosis of the jaws (ONJ)

sub-antimicrobial-dose doxycycline (SDD)

must not be used as monotherapy

can be combined with local antimicrobial delivery systems

acts via MMP (MMP-8 and MMP-9) inhibition, enzyme, cytokine reduction, osteoblast stimulation—not an antibiotic effect

only FDA-approved systemically administered HMT adjunct to SRP for chronic periodontitis

• MMP → matrix metalloproteinases

• ex: Periostat

indications of sub-antimicrobial-dose doxycycline (SDD)

for chronic and aggressive periodontitis as adjunct to SRP

useful in refractory cases and high-risk patients (smokers, diabetics, osteoporotic, genetically susceptible)

contraindications of sub-antimicrobial-dose doxycycline (SDD)

allergy to tetracycline

pregnancy / lactation

children <12 yeats

disadvantage: may reduce efficacy of oral contraceptives

benefits of sub-antimicrobial-dose doxycycline (SDD)

gains in attachment

reduced probing depth

stimulates osteoblasts

no resistance risk at 20mg dose

effective even in high-risk patients (e.g., smokers)

dosage of sub-antimicrobial-dose doxycycline (SDD)

20mg BID for 3–9 months → first round of SRP

SDD + local delivery (atridox) + SRP

demonstrated >2mm improvement in attachment gains and probing depth reductions vs SRP alone (p<0.0001) in a 6-month, 180 patient trial

Locally Administered HMTs

Used as adjuncts to surgical procedures to stimulate regeneration

Topical NSAIDs have not been approved

examples of FDA-approved Locally Administered HMTs

Enamel Matrix Proteins (Emdogain)

Recombinant human platelet-derived growth factor-BB (GEM 215)

Bone Morphogenetic Proteins (rhBMP-2 / INFUSE)

Osseointegration

clinically defined as asymptomatic rigid fixation

direct structural and functional connection between living bone and implant surface without soft tissue.

initial healing of osseointegration

Mirrors bone fracture repair

Immobility: Movement greater than 150 μm prevents osteoblast differentiation → fibrous scar tissue → nonintegration

Temperature: Bone necrosis occurs if overheating during drilling exceeds 47°C for 1 minute.

Bone Maturation

Steady remodeling state reached after ~18 months

Progresses from fast-growing, poorly mineralized woven bone to slow-growing, dense lamellar bone.

Primary stability (placement) of osseointegration

depends on implant geometry and bone quantity/quality.

Secondary stability (over time) of osseointegration

depends on implant surface and percentage of bone contact.

peri-implant soft tissues

includes oral epithelium, sulcular epithelium, a sulcus, long junctional epithelial attachment, and underlying connective tissue — similar to teeth

Implants

Bone is in direct contact with the implant

lack a periodontal ligament (PDL), cementum, and Sharpey’s fibers.

Long junctional epithelium

attaches to titanium via basal lamina and hemidesmosomes.

Peri-implant “Biologic Width”

Combined height of epithelial attachment and supracrestal connective tissue

• ~3–4 mm or 4–4.5 mm

Connective Tissue Fibers

Cannot insert into the implant surface.

Run mostly parallel or in a cuff-like circular orientation, forming a soft tissue “seal.”

Keratinized Tissue

Not required for long-term success.

may cause pain or discomfort during oral hygiene due to mobility of nonkeratinized mucosa.

Vascular Supply

Scarcer than around teeth; no contribution from PDL.

Peri-implant tissues respond to plaque with inflammation similar to periodontal tissues

probe stops in healthy tissue

~1.5 mm coronal to alveolar crest (above the bone)

Clinical Consequences (Teeth vs. Implants)

• Lack of Resiliency:

  • Implants lack a PDL, so they are rigidly attached and cannot move to compensate for occlusal disharmony.

  • Overload can cause microfractures and bone loss.

• Growth:

  • Implants placed before growth completion will not migrate or erupt with natural teeth.

  • Can lead to occlusal problems; therefore, contraindicated in growing patients.

• Maintenance:

  • Long-term success requires meticulous plaque control.

  • Frequent maintenance visits are recommended (e.g., every 3–4 months).

comprehensive periodontal management

patient education & oral hygiene

high-quality SRP + local delivery

host modulation (SDD)

risk factor modification

surgery + HMT if indicated