Simplifying implant planning and placement

Charles M. Oster

Dr Sean W. Meitner

Dr Gregori M. Kurtzman

Tue. 20 May 2025

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Implant planning and placement in the completely edentulous maxilla can present challenges both surgically and prosthetically whether a removable or fixed approach is planned. Placement of implants freehand does not take the osseous anatomy and its structures into consideration and may lead to problems such as nerve or blood vessel impingement as well as implant extension into the sinuses or nasal cavity. Guided placement has become the standard practice whether treating the completely or partially edentulous arch. While printed surgical guides are the standard practice, there may be circumstances where they are not possible.

Figs. 1a & b: Clear duplicate denture with the proposed sites outlined on the interior of the denture and guide holes created (a) and with 2 mm guided sleeves pressed into the holes (b). Sites: maxillary right second premolar, right first premolar, right canine, right central incisor, left lateral incisor, left first premolar and left second premolar.

Case presentation

A 65-year-old male patient presented for consultation on replacement of his complete maxillary denture with an implant-retained prosthesis. The patient indicated that he had been wearing his maxillary denture for 14 years and retention was poor and that he wished to eliminate the palatal coverage. Examination noted shallow vestibules and minimal retention of the denture to the arch. Further discussion with the patient to determine his expectations revealed that a removable prosthesis retained by implants would meet his expectations and allow easier home care than a fixed prosthetic approach.

Preparation of the diagnostic and surgical guide

An impression of the maxillary denture was taken extra-orally using alginate and a denture duplicator (Lang Dental) to allow fabrication of a diagnostic guide to be utilised with a CBCT scan in the planning phase of treatment. The patient was dismissed and scheduled for the CBCT scan.

Lucitone acrylic (Dentsply Sirona) was mixed and poured into the duplicator. Upon setting, the duplicate denture was removed, any marginal flash was removed with an acrylic bur and the duplicate denture was polished. Holes were drilled through the centre of the convexity of the tissue surface through the cingula of the oral surface of the anterior teeth and the central fossae of the posterior teeth of the duplicate denture with a 3/32 in. drill. In the duplicate denture, 2 mm guided sleeves were placed into the holes of the proposed sites (Figs. 1a & b).

The patient returned, and this diagnostic denture with the 2 mm guided sleeves was inserted intra-orally, and the CBCT scan was performed. The patient was again dismissed, and an appointment was scheduled for the surgical phase of treatment.

The CBCT scan data was imported into the planning software (Invivo5, Osteoid). The treatment plan was to place four implants spread around the arch to retain a new prosthesis with Atlantis Conus frictional fit abutments (Dentsply Sirona) on the implants and corresponding caps embedded into the prosthesis. The perspective sites were selected based on a preliminary review of the initial CBCT scan and the position of the available bone and its relation to the maxillary sinuses. Each potential site was analysed, and based on the analyses, a decision was made for each site regarding its suitability for implant placement.

The maxillary right first molar site was analysed, and it was determined that, although adequate buccopalatal width was present, insufficient crestal height was present inferior to the sinus floor and that sinus augmentation would be required to permit implant placement at that site (Figs. 2a-d). However, the patient preferred not to undergo sinus lift. It was decided based on that information that this site would not be used for implant placement.

The maxillary right second premolar site was analysed, and it was determined that sufficient crestal height and adequate buccopalatal width were present to allow for implant placement (Figs. 3a-d). No correction would be required in the buccopalatal or mesiodistal directions. A 4.8 × 9.0 mm Astra Tech EV implant (Dentsply Sirona) was selected for this site.

The maxillary right first premolar site was analysed for placement of a fixation screw to stabilise the full-arch surgical guide, and sufficient bone was found to be present to accommodate a 17 mm screw without contacting the maxillary sinus. No angular or linear correction would be needed (Figs. 4a-d).

The maxillary right canine site was analysed, and sufficient bone height was noted for implant placement (Figs. 5a-d). It was determined that no angular correction would be needed at this site. A 4.2 × 11.0 mm Astra Tech EV implant was planned for the site after 5 mm crestal ridge reduction.

The maxillary right central incisor site was analysed for placement of a fixation screw, and sufficient bone was noted (Figs. 6a-d). It was determined that a 1 mm offset correction would be needed to avoid the nasopalatine canal.

The maxillary left lateral incisor site was analysed, and sufficient bone was noted for implant placement without perforation of the nasal floor. However, a 15° correction to the buccal would be necessary to place the implant as planned, as well as crestal bone reduction of 5–6 mm owing to the thin crestal ridge (Figs. 7a-d). A 3.6 × 10.0 mm Astra Tech EV implant was planned for this site.

Figs. 2a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing insufficient crestal height in the maxillary right first molar site to allow implant placement without a crestal sinus lift (a–c). Site on the duplicate denture (d).

Figs. 3a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing sufficient bone to accommodate an implant in the maxillary right second premolar site and no need for angular or linear correction (a–c). Site on the duplicate denture (d).

Figs. 4a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing sufficient bone to accommodate a fixation screw in the maxillary right first premolar site and no need for angular or linear correction (a–c). Site on the duplicate denture (d).

Figs. 5a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing sufficient height of the maxillary right canine site to accommodate an implant and no need for correction (a–c). Site on the duplicate denture (d).

Figs. 6a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing sufficient bone to accommodate a fixation screw in the maxillary right central incisor site and the need for a 1 mm linear distal correction to avoid the nasopalatine canal (a–c). Site on the duplicate denture (d).

Figs. 7a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing sufficient bone and the need for a 15° buccal correction to accommodate an implant in the maxillary left lateral incisor site (a–c). Site on the duplicate denture (d).

Figs. 8a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing sufficient bone to accommodate a fixation screw in the maxillary left first premolar site and no need for angular or linear correction (a–c). Site on the duplicate denture (d).

Figs. 9a–d: Virtual planning with the diagnostic guide placed intra-orally during the CBCT scan showing sufficient bone to accommodate an implant in the maxillary left second premolar site and no need for angular or linear correction (a–c). Site on the duplicate denture (d).

The maxillary left first premolar site was analysed for a fixation screw, and sufficient bone was noted (Figs. 8a-d). It was determined that no angular or linear correction would be needed.

The maxillary left second premolar site was analysed, and sufficient bone was noted for implant placement (Figs. 9a-d). No correction would be required at this site to accommodate an implant. A 4.8 × 8.0 mm Astra Tech EV implant was planned for this site. The final plan was for placement of implants in the sites of the maxillary right second premolar, right canine, left lateral incisor and left second premolar and fixation screws in the sites of the maxillary right first premolar, right central incisor and left first premolar.

A putty base was created in the diagnostic guide using a two-part hard-setting polysiloxane material (COLTENE). Guide posts (2 × 30 mm; DePlaque) were inserted through the guided sleeves in the diagnostic guide at the implant and fixation screw sites before the putty base had set (Fig. 10).

After setting of the putty base, the guide posts were removed, and the diagnostic guide was separated from the base. The lower parts of two-piece guide posts for the planned sites for the implants and fixation screws were placed into the putty base at the sites of the maxillary right second premolar, right first premolar, left first premolar and left second premolar previously occupied by the 2 mm guide posts. A 2 mm offset lower part of the two-piece guide post was placed into the putty base at the site of the maxillary right canine with the offset positioned to the distal aspect to even out the spacing, a 1 mm offset lower part of the two-piece guide post was placed in the putty base at the site of the maxillary right central incisor and an angle-corrected lower part of the two-piece guide post was inserted into the site of the maxillary left lateral incisor (the angle correction was accomplished with the Guide Right bending tool; DePlaque; Figs. 11 & 12).

Fig. 10: Diagnostic guide on the putty base with 2 mm straight posts placed through the guided sleeves of the holes for implants in the sites of the maxillary right second premolar, right canine, left lateral incisor and left second premolar and for fixation screws in the sites of the maxillary right first premolar, right central incisor and left first premolar.

Fig. 11: Guide Right bending tool.

Fig. 12: Required 15° buccal angle correction of the guide post at the maxillary left lateral incisor site, accomplished with the Guide Right bending tool.

Figs. 13a & b: Putty base with the corrected lower parts of the two-piece guide posts replacing the 2 mm straight guide posts for the planned sites for the implants and fixation screws inserted (a). Straight and uncorrected guide posts in the sites of the maxillary right second premolar, right first premolar, left first premolar and left second premolar. Offset guide posts in the sites of the right canine and right central incisor. Angle-corrected guide post in the site of the left lateral incisor (b).

An acrylic bur was used to make indentations in the putty base so that the rectangular bases of the guide posts were flush with the tissue. This completed the base for fabrication of the corrected surgical guide (Figs. 13a & b). The 3 mm upper removable part of each two-piece guide post was placed on to the lower part of each guide post to position the 3 mm-deep in guided sleeves (Fig. 14) that were to accommodate the 3 mm depth drill stops that would be utilised during the surgery (Fig. 15).

The holes in the duplicate denture were enlarged to allow it to seat over the guide posts and their sleeves on the putty base. Primopattern LC gel (primotec) was placed to fixate the guided sleeves to the duplicate denture and then light-polymerised to complete the corrected surgical guide (Fig. 16).

Fig. 14: Guided sleeves of 3 mm in depth placed on each of the upper removable parts of the guide posts to accommodate the 3 mm depth drill stops that would be utilised during surgery.

Fig. 15: Guide Right 3 mm depth drill stops for depths from 6 mm to 15 mm.

Fig. 16: Final surgical guide on the putty base after the holes for the guide posts on the duplicate denture had been enlarged to allow seating over the guide posts and sleeves and the guided sleeves had been fixated in place. Orange indicates positioning of implants in the sites of the maxillary right second premolar, right canine, left lateral incisor and left second premolar. Green indicates positioning of fixation screws in the sites of the maxillary right first premolar, right central incisor and left first premolar.

Surgery

The patient presented for the surgical phase of treatment, and the consent forms were reviewed and signed by the patient. Local anaesthetic was administered in the maxillary arch using 4% articaine and 1:200,000 adrenaline. The surgical guide was inserted to verify seating on the arch. A 2 × 17 mm fixation screw was placed through the surgical guide at the sites of the maxillary right first premolar, right central incisor and left first premolar to stabilise the guide and prevent motion during osteotomy preparation. Utilising Guide Right 3 mm depth drill stops, the osteotomies in the sites of the maxillary right second premolar, right canine, left lateral incisor and left second premolar were prepared through the 3 mm guided sleeves in the surgical guide.

The implants were placed 4–5 mm below the alveolar crest as planned to provide adequate room for the Atlantis Conus abutments. The fixation screws and the surgical guide were removed from the mouth. An incision was made at the centre of the ridge and the soft tissue flapped to expose the crestal bone and some of the buccal and palatal bone. A surgical carbide bur was then utilised to reduce the crestal bone across the arch to 1 mm from the platform of the implants at the four sites. Alveolar crestal reduction was performed after implant placement to avoid loss of stability of the surgical guide. Cover screws were placed, and the soft tissue re-approximated and fixated with #4-0 nylon sutures in an interrupted pattern. The patient’s old maxillary denture was relined with EasySoft liner (Karlin) to accommodate the reduction in crestal height performed. A panoramic radiograph was taken to document the implant placement (Fig. 17).

Fig. 17: Panoramic radiograph taken after implant placement.

The patient was allowed to heal for four months, during which time periodic postoperative visits took place. The implants were then uncovered, and healing abutments placed. After two weeks of healing of the soft tissue, the healing abutments were removed and impression copings placed (Figs. 18a & b). A full-arch impression was taken with Permadyne heavy- and light-bodied polyether impression material (3M) in a custom tray to start the restorative phase of treatment.

A master cast was poured in ResinRock (Whip Mix) with implant analogues and GI-MASK (COLTENE) to replicate the soft-tissue architecture. Inter-implant spacing was verified with a verification jig fabricated from PATTERN RESIN (GC America). An impression of the mandibular arch was taken with alginate. The master cast was mounted with a facebow (Hanau) on a modular, semi-adjustable articulator. A jaw relation record was taken with a custom Triad resin baseplate (Dentsply Sirona) with a wax rim and Blue-Mousse VPS bite material (Parkell). The wax rim was marked to show the desired midline and tooth position, and then a protrusive bite check was done to set the occlusal parameters on the articulator. The patient chose VITA Shade B1.

A try-in was done of the full arch with denture teeth (Ivoclar) to confirm aesthetics and function. The teeth were positioned to optimise aesthetics and phonetics, but were repositioned according to the patient’s request until a satisfactory result was achieved. A buccal matrix was made on the master cast with Express VPS putty (3M) to preserve the tooth position. The dental laboratory fabricated four custom Atlantis Conus abutments and a cobalt–chromium denture framework/baseplate that incorporated the SynCone caps (Dentsply Sirona) that would retain the abutments. The denture teeth were placed on the master cast with the abutments and denture framework present. Utilising the buccal matrix, a new full-arch wax try-in was fabricated with a spacer over each abutment.

The patient returned to the office, and the abutments were placed intra-orally using the insertion guide and verified clinically and radiographically for fit and orientation. A new jaw relation record was taken and verified. The wax try-in was inserted intra-orally over the abutments to verify fit and occlusion and obtain patient approval regarding the aesthetics. The wax try-in was returned to the laboratory for processing.

The maxillary overdenture was processed without the incorporation of the SynCone caps, which would be picked up clinically using Chairside resin (Zest Dental Solutions). The finished maxillary overdenture was returned to the office for insertion.

Figs. 18a & b: Milled parallel Atlantis Conus abutments placed on to the integrated maxillary implants in the sites of the maxillary right second premolar, right canine, left lateral incisor and left second premolar (a). Intaglio surface of the maxillary overdenture with receptacles for the Atlantis Conus abutments (b).

Fig. 19: Final implant-supported prosthesis.

The finished overdenture was tried in with the SynCone caps seated on the abutments, and passive fit was confirmed, as were the occlusion and aesthetics. Chairside resin was placed into the sites in the intaglio surface of the denture where the abutment spaces were present. The overdenture was then seated intra-orally, and the patient instructed to occlude. Upon setting of the resin, the overdenture was removed with the SynCone caps embedded within. Any resin flash around the SynCone caps was removed and the areas polished. The overdenture was reinserted intra-orally, and retention and occlusion were confirmed (Fig. 19). The patient was scheduled for a follow-up appointment the following week to check fit and function.

Discussion

Implant treatment is a prosthetically driven treatment with a surgical component. Implant planning and placement in the completely edentulous arch pose clinical challenges owing to an absence of teeth to determine ideal implant positioning utilising a prosthetically driven plan. That information is also absent in virtual implant planning software unless a diagnostic guide is used during the CBCT scan. The diagnostic guide discussed can be fabricated in-office utilising a replica of the patient’s denture and placement of guided sleeves in that replica prior to capturing the CBCT scan to provide the ideal prosthetic positions for virtual planning when deciding on anatomical implant positions. That information can then be used to correct the angulation and position of the implants to maintain the desired prosthetic positioning for fabrication of an in-house surgical guide.

Conclusion

The full-arch All-on-4 treatment protocol can pose challenges to surgical placement that are then reflected in the prosthetic phase of treatment when performed with freehand implant placement. Utilisation of a surgical guide eliminates those potential positioning issues that can result from freehand placement. Replication of a complete denture allows for fabrication of a diagnostic CBCT guide to allow virtual planning that takes anatomical features into consideration and make planned implant placement more ideal for that particular patient.

The Guide Right system is a geometric approach which allows in-office planning with linear and angular correction and surgical guide fabrication, simplifying the process while eliminating the time and additional expense normally required to have the surgical guide created at a dental laboratory.

Disclosures
Dr Meitner is the developer of the Guide Right system. Dr Oster and Dr Kurtzman have no conflicts of interest.

Editorial note:

This article was also published in digital—international magazine of digital dentisty vol. 6, issue 1/2025.