Immediate Loading of Maxillary One-Piece Screw Implants Utilizing Intraoral Welding: A Case Report

International conferences have defined procedures and techniques for immediate loading, based on scientific and clinical evidence and considering various edentulous anatomic forms, the type of bone, and the length and structure of the implants used.^1–3  Clinicians from the study group of NuovoGISI have long and successful experiences with immediate loading of maxillary implants connected together by intraoral welding.^4–7  Intraoral welding can join and stabilize implants by the use of a titanium wire or bar that is permanently connected to the implants. An electric current is used to fuse the titanium to the abutments in milliseconds.

The welding procedure is performed intraorally before the immediate loading. Stabilization and fixation of the implants allows immediate loading and prosthesis insertion (provisional or definitive) to occur the same day as the surgery. By inserting a prosthesis with adequate retention and stability the same day as the surgery, patient complaints and discomfort can be avoided or substantially reduced. The instantaneous stability that results from the splinting can reduce the risk of failure during the healing period. Intraoral welding can also eliminate errors caused by unsatisfactory impression making.

The intraoral welding machine was developed by Pierluigi Mondani⁸  of Genoa, Italy, to permanently connect 1-piece implants or abutments (sometimes called welding or dedicated welding abutments) to a titanium wire or bar by means of an electric current (Figure 1). The current is applied for a short period of time (4 ms) so the heat generated does not cause any pathology or patient discomfort.

One-piece implants are placed without flaps (Figure 2). The titanium wire or bar is bent and aligned passively to the contour of the labial and lingual surfaces of the implants (Figure 3) before applying the electric current to permanently connect the bar to the implants.

This procedure can be modified and used in 2 steps with approximately 4 months between surgeries for atrophic bony ridges. Submerged implants are inserted in the maxillary tuberosity regions during the first surgery. One-piece implants are placed anteriorly during the second surgery and all of the implants welded immediately to a titanium bar.⁹ 

The surgical protocol of this technique has 4 objectives:

• Number of implants—As many implants as possible should be placed, corresponding to the number of missing teeth to be replaced.

• Primary stabilization—All implants must reach and penetrate the deep cortical bone to achieve bicorticalism, which provides primary stability.^10,11 

• Immediate splinting—Strong and stable splinting of the implants can be obtained using a 1.2-mm wide titanium supporting bar, set internally on the mucosa without any compression and welded to each implant by intraoral solder.^12,13  The supporting bar must be placed so that the emerging implant abutments rise up free of any interference in the oral cavity.

• Temporary prosthesis—During the surgical session, a temporary resin prosthesis is inserted. Occlusal plane height must be correct. A lingualized (lingual contact) scheme of occlusion is recommended. The upper anterior teeth are best arranged without any vertical overlap. The amount of horizontal overlap is determined by the jaw relationship. A vertical overlap for appearance can be used, provided that an adequate horizontal overlap is included to guard against interference within the functional range.¹⁴ 

The ideal screws for the maxillary temporary prosthesis are those with wide threads, as they can provide greater stability when inserted into bone that is not particularly compact.¹⁵ 

A healthy 67-year-old Caucasian woman presented for treatment at the office of 1 of the co-authors (CDL) with an unstable maxillary complete prosthesis supported by 6 anterior residual roots (Figures 4 and 5). The maxillary bone was checked with a thickness gauge, examined radiographically, and found to be appropriate for dental implants. After extraction of the retained roots, 14 implants were inserted in 1 session. A panoramic radiograph (Figure 6) confirmed the deep bicortical placement of the implants.

Immediate stabilization of the implants was achieved by welding (Aptiva Intraoral Welding Unit NS1100, Vicenza, Italy) each implant to a 1.5-mm supporting titanium bar (Bio-Micron, Milano, Italy), which previously had been bent to fit passively on the palatal mucosa (Figure 7). A provisional resin prosthesis was inserted, which provided an acceptable vertical dimension and a balanced occlusion (Figure 8).

After 90 days a panoramic radiograph suggested complete integration (Figure 9) and a healthy mucosa was observed (Figure 10). The definitive full-arch gold-ceramic maxillary prosthesis was inserted (Figure 11), which greatly pleased the patient and her family.

Oral hygiene procedures were demonstrated to the patient and reviewed at all future appointments (Figure 12).

The case was later completed with a lower full arch prosthesis on implants and natural teeth. The 13-year follow-up radiograph shows satisfactory preservation of bone surrounding all of the implants and a healthy appearance of the oral mucosa (Figures 13 and 14).

When possible, surgical trauma can be reduced by the insertion of implants without flaps. This technique, proposed by Tramonte,¹⁶  can be performed when the bony crest is wide and an adequate amount of attached gingiva is present. The technique allows for uneventful healing, a reduction of postsurgical inflammation, and only moderate inconvenience for the patient, who can eat efficiently the same day.

The soft tissues underlying the welded bar experience minimal inflammation, similar to that which can be observed with 2-stage implants.^17,18  The successful use of intraoral welding for maxillary immediate restorations has been reported in the dental literature.^19–21 

Long-term success of restorations fabricated by immediate loading of maxillary 1-piece implants utilizing intraoral welding has been reported in the dental literature. The technique can also be used with implant abutments and submerged implants. Among the advantages of intraoral welding are immediate stabilization of the implants, immediate provisionalization, reduced risk of failure during the healing period, elimination of errors caused by unsatisfactory impression-making, and a potential reduction in patient complaints and discomfort.