How to: Rebuild an arch using a hybrid implant

Many advancements have occurred in dental implantology in the past several decades. Perhaps one of the most significant developments that provides the dental patient with the greatest benefit is the hybrid implant. The hybrid implant is a small diameter implant that offers full prosthetic versatility. It has been proven to provide long-term success in a myriad of clinical cases. One of its advantages is providing implant anchorage in cases of minimal bone width.

The American Dental Skinny® 2.4 implant is one such hybrid that is effortless to place, having an extremely friendly delivery system. It is offered to provide the dental profession the broadest selection of threaded implants for all bone types.

Case presentation
The patient is a petite 68-year-old woman. She presented with a failing maxillary roundhouse bridge. The patient was aware the bridge was failing and opted for sequential restorations based on need and location where the failing roundhouse could be separated. The bridge was bisected between the maxillary right lateral incisor (pontic) and the right central incisor (abutment). The ridge was extremely narrow and the patient vigorously rejected bone grafting recommendations (Fig. 1). The abutment tooth was removed, and the patient wore a transitional removable partial denture (RPD) until healing occurred and was ready for implant placement.

Phase one
Following pre-operative evaluation and treatment planning, the surgical portion began. A blunt dissection exposed the minimal residual alveolar ridge. The osteotomy was initiated with a Locator Drill to establish location and trajectory (Fig. 2). Care was taken in the location and trajectory to optimize implant placement between the cortical plates.

The osteotomy was then completed using the internally irrigated Final Sizing Drill, which features a built in countersink. The Final Sizing Drill matches the geometry of the implant and is 2.4 mm in diameter. The Skinny 2.4 mm implant was delivered to the osteotomy (Fig. 3) and then threaded into the osteotomy using the vial cap driver of the delivery system. The vial cap may be removed and replaced with any 4 mm square driver. The straight hand driver was used for this case.

The implant is threaded to final depth (Fig. 4). The limited dimension of the alveolar ridge is apparent in the visualization directly up the long axis of the implant. An implant of greater diameter would have proven problematic. A case of this type demands an implant with all prosthetic options and capabilities. The first stage surgical cover screw is packaged with its own 0.050”/1.25 mm hex driver. This driver was used to remove the fixation screw from the green implant mount driver and also to drive the first stage surgical cover screw.

After the first implant was placed and confirmed, the second implant was placed distal to establish the extent of implant placement. The second implant location was determined using the Initial Locator Drill. The width of the residual ridge was narrow. The treatment planning of any case may be as individual as the practitioner. It’s appropriate to have a hybrid implant on hand to solve potential unexpected bony configurations. If more width is encountered, then an implant of greater diameter may be used. But it’s important that there be no compromises by using a small diameter hybrid implant in cases with compromised ridge. The only other option would be to perform a bone grafting or ridge expansion procedure, which exposes the patient to another surgical procedure and a delay in completion of treatment.

The second implant was delivered to the osteotomy using the vial cap driver from the delivery system. It was threaded to depth as far as was comfortable digitally.

The cap was removed and the implant was threaded to final depth using the 4 mm straight hand driver.

The first stage surgical cover screw was threaded into the implant using the premounted delivery driver.

The surgical phase of this quadrant was completed by repeating the previous steps and placing two more hybrid implants between the two that were illustrated. The case was sutured for closure, a radiograph was taken and the patient was dismissed.

After three months of healing, during which time the patient wore a transitional removable appliance without incident, she presented to uncover the implants. A panoramic radiograph was taken confirming proper healing (Fig. 5). The implants were surgically exposed and the same 0.050-inch hex driver was used to remove the first stage surgical screw. Tissue healing abutments were placed.

After two weeks of healing, the tissue healing abutments were unthreaded. The same drivers that were used at the time of surgery were then used as transfer copings. They were inserted into the implants and secured with the same fixation screws as at the time of surgery. It’s important to locate the flat of the impression coping in a manner that it can be remembered, usually to the buccal.

A periapical radiograph was taken at this time to ensure proper interfacing of components.
Conventional crown and bridge impression techniques and materials were used to take an impression. After the impression material was set and the tray was removed, the impression copings were removed by unscrewing the fixation screws. Analogs were affixed to the transfer copings and the transfer copings were reinserted into the impression using the flats for indexes.

The impression was poured up creating an implant level master model. The impression copings were removed and replaced with cement on abutments and milled for parallelism with the aid of a surveyor.

At the next appointment, the modified abutments were threaded into the implants and a radiograph was taken. Conventional crown and bridge impression techniques were employed, and the final bridge was fabricated and inserted (Fig. 6). This completed the first phase of this full maxillary restoration. The patient was very satisfied with the result and that it was accomplished with no bone grafting, which greatly minimized surgical chair time and expense. This two-phased approach made this case feasible from a time and economic standpoint with no compromise in outcome.

Phase two
The patient was comfortable for about 2½ years until the remaining segment of the original roundhouse conventional bridge failed as anticipated. The bridge and the failed teeth were removed, and a transitional RPD was fabricated for the patient. The patient then presented for the second phase of the full arch reconstruction.

A panoramic radiograph was taken showing phase one implants and the remaining edentulous ridge was exposed. Many cases present unexpected anatomical challenges that are encountered at the time of surgery. Although cone beam tomography is helpful, not all practices and patients can incorporate this emerging technology. Having a hybrid implant such as the Skinny 2.4 available can save a case like this.

Surgical reflection via blunt dissection revealed the narrow ridge with an unusual diminishing volume to the distal. The osteotomy is begun, using an Initial Locator Drill and completed with the Final Sizing Drill (Fig. 7).

The implant was digitally threaded as deep as bone density permits (Fig. 8). A 4 mm square driver was used to complete seating to final depth.

A second osteotomy was begun, taking advantage of “islands of bone.” Final sizing drill completed the osteotomy (Fig. 9). Every attempt was made while bisecting a very narrow ridge to achieve parallelism with the first implant, however because the Skinny 2.4 has total prosthetic versatility, corrections in angulation can be made during the prosthetic phase. With green drivers left in place, the third osteotomy is prepared taking advantage of bony ridge bulge. 

The final implant is threaded to depth following previous protocol (Fig. 10). Drivers are removed using a 0.050” hex tool exposing internal geometry of implants.

First stage surgical cover screws are placed and then the tissue is closed with sutures. A radiograph is taken.

Three months later, the patient returned and the implants were uncovered. The uncovering was accomplished minimally without a full flap. The tissue healing abutments were placed. The patient was dismissed and returned two weeks later for placement of the original green drivers that were used as indexed transfer copings (Fig. 11).

The proximal abutment of the phase one bridge incorporated an inlay/wing for added strength of the final completed restoration. A closed tray impression technique was used to create a master model. Straight cement on abutments were placed and secured to the master model (Fig. 12). The abutments were custom milled in the laboratory on a surveyor.

The patient returned and the tissue healing abutments were placed with the custom milled abutments in proper orientation (Fig. 13). A final panoramic radiograph was taken (Fig. 14), and the case was completed (Fig. 15).

Conclusion
This case demonstrates the need for, and the benefit of, a small diameter hybrid implant. The importance of a small diameter implant with full prosthetic capability can not be overstated. In challenging cases, or in cases where there’s not an abundant volume of bone, the Skinny 2.4 can offer the patient and the practitioner the benefits of decades of dental implant research and innovation. This case couldn’t have been accomplished before the development of the Skinny 2.4 without extensive, surgically invasive bone grafting and/or ridge expansion; these procedures introduce additional surgery and potential complications. Ideally all therapies should be accomplished with the least number of surgeries and procedures. The Skinny 2.4 should be on hand to immediately solve implant challenges.