CLINICAL PERSPECTIVES FOR REVISED DRILLING GUIDELINES FOR PW IMPLANTS ART1090

Recommended Drilling Guidelines For Parallel Walled Implants Based On Bone Quality:

Emerging techniques in dental implant surgery are trending towards one-stage procedures and immediate loading.Unlike a two-stage approach, these procedures may be more hallenging and aggressive; and therefore may require a high level of initial primary stability of the implant. To this end, new drilling guidelines have been recommended by BIOMET 3i for parallel walled implants, to increase initial primary stability.

Anatomy Of An Implant

In order to implement the most appropriate drilling protocol based on bone quality, it is important to understand the critical dimensions of an implant. These dimensions include the apical diameter of the implant, the major and minor diameter of the implant body and the diameter of the implant collar (Figure 1).

based on the diameter of the chosen implant. For example, in softer bone types, the final diameter twist drill should be selected so that the osteotomy is slightly undersized (smaller than the minor diameter of the implant) thus allowing for bone compression upon insertion of the implant. Insertional torque should also be considered when selecting the final twist drill. However, the insertional torque that is achieved may not be constant among all bone

densities. Therefore, it may be necessary to modify the drilling protocol to achieve both adequate compression and insertional torque.

The clinical case presentation to follow demonstrates placement of a 5mm diameter parallel walled NanoTite™ Certain® Implant in soft (Type IV) bone. A single-stage protocol was followed.

Based on these dimensions and clinician assessment of bone quality, BIOMET 3i has established drilling guidelines to increase bone-to-implant contact. Surgical Protocol Selection Based On Bone Quality Once a clinician has determined bone quality at each implant site, the recommended drilling protocol should be selected based on the diameter of the chosen implant. For example, in softer bone types, the final diameter twist drill should be selected so that the osteotomy is slightly undersized (smaller than the minor diameter of the implant) thus allowing for bone compression upon insertion of the implant.

Insertional torque should also be considered when selecting the final twist drill. However, the insertional torque that is achieved may not be constant among all bone densities. Therefore, it may be necessary to modify the drilling protocol to achieve both adequate compression and insertional torque. The clinical case presentation to follow demonstrates placement of a 5mm diameter parallel walled NanoTite™ Certain® Implant in soft (Type IV) bone. A single-stage protocol was followed. This clinical case example is representative of the individual clinician’s experience in clinical practice and may not be indicative of other cases due to varying patient subsets and clinical scenarios. To review the complete recommended drilling guidelines for placement of BIOMET 3i Implants based on bone quality, please refer to the Surgical Manual (CATSM).

Placement Of A 5mm Diameter ParallelWalled NanoTite™ Certain®

Implant In Soft (Type IV) Bone: A Case Presentation

INITIAL PATIENT PRESENTATION

A 70-year-old male patient presented with a partially edentulous posterior right mandible (Figure 1). A failed fixed partial denture previously supported by teeth Nos. 27, 29 and 31 [43, 45 and 47] had been removed six months prior due to root fracture of tooth No. 27 [43] and severe periodontitis of tooth No. 31 [47]. The patient was referred to the dental clinic seeking implant treatment to restore his ability to masticate properly. The patient desired a fixed restoration for his missing dentition. The treatment plan accepted by the patient included extraction of the remainder of tooth No. 29 [45] and placement of three dental implants to support fixed restorations.

DIAGNOSIS

• Partially edentulous mandibular right posterior quadrant

• Retained pier abutment for preexisting PFD, tooth No. 29

• Adequate bone quantity for implant placement without

the need for grafting

• Adequate keratinized soft tissue in the edentulous area

for implant placement

• Adequate interocclusal clearance with the opposing

Dentition

TREATMENT PLAN

• Extraction of the retained tooth No. 29 [45]

• Placement of three implants into tooth sites Nos. 27, 28

and 30 [43, 44 and 46] in a single-stage protocol

• Placement of Encode® Healing Abutments in lieu of cover

screws

• Soft-tissue closure with intermittent sutures around the

healing abutments

• Impressions of the Encode Healing Abutments in three

months for fabrication of definitive Encode Abutments

and PFM restorations

IMPLANT PLACEMENT

On the day of surgery, the patient received local anesthesiaby infiltration in the mandibular right posterior quadrant. The remainder of tooth No. 29 [45], the mandibular right second bicuspid, was extracted. A full thickness mucoperiosteal flap with vertical releasing incisions was reflected to the buccal and lingual aspects of the ridge to allow visual inspection of the position of the mental foramen and the terminal branch of the mental nerve (Figure 2).

Measurements were taken to determine the height of bone from the mental foramen to the top of the crest (Figure 3). With the implant drilling unit set at 1500rpm, preparation of the osteotomy for tooth site No. 30 [46] began with an ACT® Pointed Starter Drill (ACTPSD) to mark the ideal location for placement of the first implant and to pierce the cortical bone (Figure 4). Copious irrigation was used during high speed drilling. Initial drilling was also performed in tooth sites 27 and 28 [43 and 44]. Preparation of the osteotomy in tooth site No. 30 continued (Figure 5) with a 2mm Twist Drill (ACT2015). During initial drilling, the bone quality was deemed to be soft (Type IV). Therefore, a clinical decision was made to undersize the osteotomies based on newer drilling guidelines aimed at ensuring a high level of initial primary stability for the implant.

CLINICAL TIP: The accumulation of bone debris in the cutting flutes of the 2mm Twist Drill provides a good indication of bone quality during initial preparation of the osteotomy. For example, less accumulation of bone debris may be indicative of the presence of soft bone (Type IV) in the site. To verify the direction and position of the implant steotomies, Direction Indicators (DI100) were placed into the three sites (Figure 6). The 2mm Twist Drill was used again to the full predetermined implant depth for each site.

A Pilot Drill (PD100) was placed into the osteotomy created by the 2mm Twist Drill (Figure 7) and advanced to the depth marked with a laser line to shape the coronal aspect of the implant site. Preparation of the osteotomy in tooth site No. 30 continued with a 3.25mm Twist Drill (ACT3215) to the desired depth (Figure 8) for placement of a 5mm diameterx 10mm length NanoTite™ Certain® Implant.

 NOTE: The osteotomies for tooth sites 27 and 28 [43 and 44] were prepared following the guidelines for placement of 4mm diameter implants in soft bone. Next, a 5mm Countersink/Pilot Drill (CD500) was placed into the coronal aspect of the osteotomy (Figure 9) and advanced to the first laser line (for crestal placement) to shape the coronal aspect of the implant site. The drill was used at 1200rpm. Based on the newer drilling guidelines for placement of parallel walled implants in soft bone, this was the last drill used prior to placement of the implant.

A 5mm diameter NanoTite™ Certain® Implant was picked up from the sterile package sing a Certain Implant Placement Driver Tip (IIPDTS). The implant was carried to the mouth Figure 10) and placed into the prepared site at approximately 15-20rpm at a torque of 40Ncm (Figure 11). Following the recommended protocol for placement of NanoTite Implants, irrigation was not used during implant placement allowing the blood to contact the implant surface and thus, maximizing fibrin concentration at the site. Final implant positioning was accomplished with the hand ratchet to ensure primary stability of the implant. The implants for the two other sites were then placed (Figure 12).

CLINICAL TIP: When using the hand ratchet for final implant positioning in the osteotomy, use light downward pressure with the thumb or forefinger to maintain engagement and alignment of the driver tip and the internal interface of the implant.

Encode® Healing Abutments consistent with the size of the implants placed and the tooth anatomy/soft-tissue depth at each implant site, were placed into the internal interfaces of the implants and visually inspected to ensure full seating (Figure 13). The soft-tissue flaps were closed around the healing abutments with 4.0 Vicryl (Ethicon, Inc.) interrupted sutures (Figure 14). A periapical radiograph was taken to ensure complete seating of the healing abutments. The patient was prescribed 2g V-PC (Kåvepenin) Ibuprofen as needed and was instructed to rinse with chlorhexidine gluconate (CHX) rinse three times per day.

The patient was seen for a post-operative visit 10 days later (Figure 15). Healing was progressing as planned. Due to the poor bone quality, a clinical decision was made to wait

three months before seeing the patient for impressions of the Encode Healing Abutments, fabrication of definitive Encode Abutments and fabrication of the PFM restorations.