Surgical Procedures in Partially Edentulous

Clin Oral Impl Res 2000: 11 (Suppl.): 83–100 Printed in Denmark ¡ All rights reserved

Copyright C Munksgaard 2000

ISSN 0905-7161

Chapter 5

Surgical procedures in partially edentulous patients with ITI implants
Buser D, von Arx T. Surgical procedures in partially edentulous patients with ITI implants. Clin Oral Impl Res 2000: 11 (Suppl.): 83–100. C Munksgaard 2000. Today, partially edentulous patients represent the majority of patients seeking treatment with implant-supported prostheses. This chapter presents the specific aspects of the surgical handling of partially edentulous patients with either single-tooth gaps, extended edentulous spaces or distal extension situations. Due to differences in treatment objectives, a distinction is made between sites without esthetic priority (non-esthetic sites) and with esthetic priority (esthetic sites). In non-esthetic sites, the primary goal of the surgical therapy is to achieve a predictable hard and soft tissue integration of the implant to re-establish function with the implant-supported prosthesis. In esthetic sites, the goal of surgical therapy is to achieve successful tissue integration and to obtain esthetic soft tissue contours to re-establish both function and esthetics. Therefore, the surgeon must have a clear understanding of the specific needs in a given situation, and must master the necessary surgical techniques concerning a correct implant placement and a correct soft tissue handling to achieve the treatment objectives. In non-esthetic sites, a non-submerged approach is clearly preferred, thus avoiding a second-stage procedure for abutment connection. If a soft tissue correction is necessary to re-establish keratinized peri-implant mucosa, this is done at the time of implant placement with mucogingival surgery. In esthetic sites, a submerged implant placement is preferred to achieve esthetically pleasing soft tissue contours. If a soft tissue augmentation is necessary, this is done at the time of implant placement with connective tissue grafts. Thus, the second surgical procedure after 8–10 weeks of healing is reduced to a mucosaplasty like a punch biopsy, avoiding an open flap procedure. Based on favorable properties of the TPS surface, short implants (6 or 8 mm) and short healing periods of 3–4 months have been successfully utilized in partially edentulous patients in the last 14 years. The introduction of the SLA surface allows a further reduction of the healing period to 6 weeks of healing in all sites with normal bone density (class I–III). In summary, the ITI philosophy offers straightforward surgical concepts to predictably achieve the treatment objectives with the least demanding surgical protocol, reducing the related chairtime and costs for the patient and the clinician. Daniel Buser, Thomas von Arx
Dept. of Oral Surgery, University of Bern, Bern, Switzerland

Key words: esthetic sites – ITI implants – non-esthetic sites – nonsubmerged approach – SLA surface – submerged approach – surgical procedures Committee Members: Leon A. Assael, USA, Jay Beagle, USA, Alexandra Behneke, Germany, JeanPierre Bernard, Switzerland, Daniel Buser, Switzerland, Karl Dula, Switzerland, Christian Foitzik, Germany, Michael Gahlert, Germany, So ¨ lve Hellem, Sweden, Hans Peter Hirt, Switzerland, Hideaki Katsuyama, Japan, Barbara Lehmann, Switzerland, Herbert Niederdellmann, Germany, Stephen Rimer, USA, Marcel Scacchi, Switzerland, Wilfried Schilli, Germany, Christiaan ten Bruggenkate, The Netherlands, A.V. van Gool, The Netherlands, Thomas von Arx, Switzerland, Gerhard Wahl, Germany, Dieter Weingart, Germany Prof. Dr. Daniel Buser, Department of Oral Surgery, School of Dental Medicine, University of Berne, Freiburgstrasse 7, CH-3010 Berne, Switzerland Tel.: π41 31 632 25 55 Fax: π41 31 632 98 84 e-mail: daniel.buser/zmk.unibe.ch

ITI implants have been increasingly utilized for the rehabilitation of partially edentulous patients in the past 14 years. As with Brånemark implants, the clinical testing of ITI implants started more than 25 years ago, primarily in fully edentulous patients for implant-supported bar-type overdentures. These implant prototypes were all one-part implants such as the TPS screw or the type F hol-

low-cylinder implant, meaning that the abutment was an integral part of the implant (monocorp design). Retrospective studies demonstrated promising long-term results with these implant types in this specific indication (Ledermann 1979, 1984; Babbush et al. 1986; ten Bruggenkate et al. 1990; Krekeler et al. 1990; Ledermann 1996). In the 1980s, based on this positive clinical experience 83

Buser & von Arx with osseointegrated ITI implants in fully edentulous patients, clinicians started to use ITI implants more and more in various clinical situations in partially edentulous patients, such as single-tooth gaps, distal extension situations or extended edentulous spaces. This trend was supported by the development of two-part ITI implants in 1985/86 (see chapter 1), since these newly designed implants offered much more flexibility for the clinicians from a prosthetic point of view. This progress has led to a significant expansion of implant therapy in the 1990s. Today, more than 80% of patients treated with dental implants are partially edentulous (Bernard et al. 1995; Buser et al. 1997). This development has had certain consequences for the design and clinical utilization of dental implants. First, the number of inserted implants per patient has clearly dropped in recent years. The latest clinical studies reported an average of approximately two implants per patient (Bernard et al. 1995; Buser et al. 1997, 1999a). Therefore, most implant reconstructions are no longer supported by 4–6 implants splinted together in a cross-arch arrangement to reinforce the anchorage base. Today, a majority of implant prostheses such as single crowns or short-span fixed partial dentures are supported by only one or two implants. Second, implants are frequently placed in areas of the jaw where the bone density is quite often low, the bone height reduced, but the functional load high. This is particularly true for implants in posterior areas of both jaws. In sites with these anatomical characteristics, short implants have to be utilized quite often due to a reduced bone height. Summarizing these aspects, a significant number of implants – since they are placed in posterior areas to support single crowns or short-span bridges – have to withstand a clearly increased functional stress at the bone-implant interface and at the implant-abutment complex in comparison with multiple implants being splinted in a crossarch arrangement. Therefore, implants have to be appropriately designed in order to be successful in these demanding clinical situations. Based on these increased requirements for dental implants, biomechanical aspects as well as surface properties of titanium implants have become topics of interest in implant dentistry in recent years. They are crucial for the long-term success of endosseous implants in demanding clinical situations as outlined above. In the following, the surgical procedures used in partially edentulous patients will be presented in detail. It was decided by the surgical group of the ITI Consensus Conference to distinguish between implant placement in sites without esthetic priority (‘‘non-esthetic sites’’) and sites with esthetic prior84 ity (‘‘esthetic sites’’), since significant differences in the surgical approach are apparent between these two groups. Implant placement in non-esthetic sites General remarks Non-esthetic sites still represent the majority of sites treated with endosseous implants. This includes a variety of implant indications listed in Table 5.1. The primary objective of implant therapy is clearly the re-establishment of function, whereas esthetic aspects are less important. Further objectives include (Table 5.2) the achievement of a longterm result with the least demanding surgical and prosthetic procedure for the patient and the clinician, to reduce the chairside time and the related costs. Hence, a non-submerged approach is clearly preferred, to avoid a second surgical procedure. If necessary, special soft tissue techniques are utilized to maintain or create a keratinized peri-implant mucosa at the time of implant placement. Consequently, the shoulder of the integrated implant is normally located at the soft tissue level, allowing easy access for the subsequent prosthetic procedures. In most cases, the patients are restored with cemented restorations utilizing conical solid abutments. As outlined in chapter 1, the implantabutment connection is based on the morse taper principle, with an 8o inner cone (Sutter et al. 1988, 1993). This interface provides an optimal friction fit, thereby transmitting functional loading forces from the abutment directly to the implant body and from there into the surrounding bone structure without exerting undesirable bending moments to the abutment screw. This connection is clearly superior from a biomechanical point of

Table 5.1. Various indications in non-esthetic sites O O O O O Distal extension situations in both jaws Single-tooth gaps in the mandible Single-tooth gaps in the posterior maxilla Extended edentulous spaces in the mandible Extended edentulous spaces in the posterior maxilla

Table 5.2. Treatment objectives in non-esthetic sites O Main emphasis: re-establishment of function O Achievement of long-term stability from a functional point of view O Least demanding surgical procedure for patient and clinician allowing for successful tissue integration with high predictability » Non-submerged approach is clearly preferred O Maintenance or establishment of keratinized peri-implant mucosa

Surgical procedures in partially edentulous patients view when compared with a flat hex-top connection (Sutter et al. 1993). In distal extension situations in standard cases, implant-borne restorations are normally not extended beyond the first molar area for functional, practical and economic reasons. This is in accordance with well-documented long-term studies evaluating the number of occlusal units necessary for sufficient masticatory function (Ka ¨ yser 1989). If an existing upper second molar requires an occlusal stop to avoid overeruption, the implantborne restoration in the mandible can be extended to the mesial area of the second molar. In these cases, the mandibular first molar is replaced by two implants to be restored with two premolarsized units of approximately 8 mm mesio-distal diameter. The use of premolar-sized units for implantborne fixed partial dentures (FPDs) is recommended. This has proven its efficacy in more than 10 years of clinical experience (Buser et al. 1988; Bra ¨ gger et al. 1990; Belser et al. 1996a; Belser & Buser 1997). In fact, a crown of 7–8 mm mesio-distal diameter is ideal to allow a harmonious axial profile gradually emerging from the implant shoulder (ø 4.8 mm) to the maximum circumference. In addition, the occlusal table is reduced, hereby diminishing the risk of unfavorable bending moments for the implants and their components. There is only one exception to that rule – namely, the single-tooth replacement in a molar site. For this indication, the wide-neck implant (WN 4.8) was developed in the late 1990s. The larger diameter of 6.5 mm in the shoulder area allows a harmonious axial profile of the molar crown. As far as number and distribution of implants are concerned, the following guidelines for routine use have been established over the past 14 years.

Fig. 5.2. One implant per missing tooth is used in special circumstances such as in implant sites with reduced bone height. The two 6 mm SLA implants are splinted to a longer 10 mm implant.

Fig. 5.3. A distal extension situation can also be treated with two implants distally and a 3-unit FPD with a mesial cantilever.

Fig. 5.1. ITI philosophy for treating a 3-unit gap: two implants support a 3-unit FPD with a central pontic. Radiographic follow-up at 5 years with two SLA implants.

O In case of three missing occlusal units and sufficient bone anatomy, the standard solution consists of the placement of two implants to support a 3-unit FPD with a central pontic (Fig. 5.1). O The replacement of each premolar unit by one implant is reserved for clinical situations in which either diameter-reduced or short implants of 6 or 8 mm length have to be used (Fig. 5.2). O If a mesial implant cannot be inserted due to anatomical restrictions, a 3-unit FPD with a mesial cantilever has proven to be a viable alternative (Fig. 5.3). O A distal cantilever unit or connection to natural teeth should only be used in exceptional situations. Recently, it has been proposed that at least three implants be inserted in a distal extension situation, with the fixtures placed in a tripod fashion (the central implant offset buccally) rather than in a straight line (Rangert et al. 1997), the idea being 85

Buser & von Arx to diminish bending moments and potential biomechanical complications (screw and abutment loosening, fractures of components of the implantabutment complex). This theoretical recommendation, however, appears impractical from a clinical point of view because of space limitations in either mesio-distal or orofacial dimensions, and it increases the related treatment costs significantly. With regard to ITI implants, this recommendation does not apply, since ITI implants (a) achieve a significantly stronger bone anchorage with a rough TPS or a microrough SLA surface when compared to titanium implants with a machined surface (Buser et al. 1999b); b) have a much stronger implant-abutment complex based on the morse taper principle when compared to a flat hex-top connection (Sutter et al. 1993); and c) are preferably restored with cemented restorations in posterior areas, eliminating the risk for screw loosening (Buser et al. 1988; Bra ¨ gger et al. 1990; Belser et al. 1996a; Belser & Buser 1997). central point of the edentulous space is normally chosen for the preparation of the implant bed. Selection of implant type The solid-screw implant, with its various dimensions (S. 4.1, S 4.8, S 3.3, NN 3.3, WN 4.8), is exclusively utilized in these applications. The selected implant diameter depends on the crest width available, as outlined in chapter 3. A minimal crest width of 4.8 mm is required for the diameter-reduced screw implant (S 3.3). This implant type should be splinted with other implants whenever possible, since it has a certain risk for a fatigue fracture. It is therefore not suitable for applications risking excessive bending moments, such as for the single-tooth replacement of molars or canines. In the case of a reduced bone height leading to the utilization of short implants (6 or 8 mm), the placement of wide-body implants (S 4.8 mm, WN 4.8) is preferred if the crest width allows for it (minimal width of 6.2 mm). This is quite often feasible, particularly in molar sites. In case of short (6 and 8 mm) or diameter-reduced (S 3.3) implants, additional implants are recommended to increase the anchoring base in the bone. In addition, splinting these implants together is recommended. In these special situations, one implant is utilized per missing tooth. Otherwise, only two implants are necessary to support a 3- or 4unit FPD, and three implants for a 4- or 5-unit FPD (see above). The narrow-neck implant (NN 3.3) is primarily utilized for single-tooth gaps in the anterior mandible, whereas the wide-neck implant (WN 4.8) is applied for single-tooth gaps in the molar area of both jaws. Selection of implant length The implant length to be chosen depends on the vertical bone height and the preoperative radiographic analysis. In standard situations, the long-

Preoperative examination in non-esthetic sites Clinical evaluation During preoperative examination, the following clinical parameters have to be assessed: (a) the sagittal and transversal relationship, (b) presence of an intermaxillary distance of at least 33 mm to allow the preparation of the implant bed with the shortest drill, (c) the evaluation of the local bone anatomy, when necessary with a bone mapping procedure, and (d) the evaluation of the local soft tissue conditions. Radiographic evaluation In standard cases, the utilization of a panoramic radiograph and/or periapical radiographs is sufficient. Quite often, the panoramic radiographs are combined with steel balls of 5 mm diameter to evaluate the distortion factor of the radiograph (Buser et al. 1990). Tomograms or CT scans are reserved for special clinical situations such as patients presenting with bone defects. CT scans should not be used routinely, since they cause a significant radiation exposure to the patient (Dula et al. 1996), and they are quite costly in most countries. Selection of implant location Based on the already outlined concept of using primarily fixed partial dentures with premolar-sized units, the distances from the root surface of adjacent teeth to the central axis of planned implants are chosen based on the 5–12–19 mm rule. This rule does not apply in single-tooth gaps, where the 86

Fig. 5.4. Due to the utilization of short 8 mm implants, a sinus grafting procedure could be avoided.

Surgical procedures in partially edentulous patients est possible implants up to 12 mm are chosen. Since bicortical stabilization is not necessary for ITI implants, with their roughened titanium surface, a security distance of 1–2 mm to the mandibular canal should be respected whenever possible. This conservative concept offers minimal risk of damaging the neurovascular bundle (Bernard et al. 1995). In contrast, a surprisingly high frequency of nerve complications (14% after stage I surgery; still 4% at three years of follow-up) has been reported for Brånemark implants with a machined surface seeking bicortical stabilization on the roof of the mandibular canal (Higuchi et al. 1995). In the maxilla, the available bone height is always utilized as much as possible, since a minor perforation of the maxillary sinus does not appear to create clinical problems. The successful utilization of short 6 or 8 mm ITI implants, with their excellent bone anchoring properties, makes it frequently possible to avoid demanding surgical procedures such as sinus grafting in the maxilla or nerve lateralization in the mandible (Figs 5.4 and 5.5). Surgical procedure in non-esthetic sites At the beginning, a midcrestal incision of the mucosa is carried out, whenever possible located in keratinized mucosa. Following elevation of the mucoperiosteal flaps, the alveolar crest is examined. Quite often, crest flattening is indicated to achieve a flat crest surface. The surgeon, however, should ensure that an extended opening of cancellous bone is avoided. Subsequently, the appropriate implant positions can be selected and marked with a small round bur. The utilization of surgical guides is not advocated for all patients, but is quite useful in extended edentulous situations without suitable landmarks, such as a missing canine. The preparation of the implant bed is carried out with spiral drills of increasing diameter. These spiral drills are characterized by an excellent cutting quality and overdrilling of only 0.4 mm, which is important in posterior sites in the mandible. A recent in vitro study demonstrated that these drills are long-lasting with an appropriate sterilization protocol, since they can be used for the preparation of more than 50 implant beds (Chappuis 2000). Between the different spiral drills, the utilization of round burs and profile drills is recommended to open the entrance of the implant bed. Depth gauges of various dimensions are useful to check the direction of the prepared implant axis and the sink depth. Tapping of the thread is done in recipient sites with normal bone density (class I–III), whereas no tapping is carried out in spongy bone (class IV). Tapping and implant insertion can be done either with a hand ratchet or with an adapter attached to a special contra-angle handpiece. Implant insertion with the insertion device requires a very slow speed of approximately 15 rpm. ITI implants are sold with a premounted insertion device allowing a non-touch handling of the implant. When the implant reaches the final vertical position – recognizable by increasing resistance to insertion – the insertion device can be easily detached with the help of a fixation key and a counter-clockwise rotation of the handpiece. The appropriate insertion depth depends on the clinical situation and the personal preference of the surgeon. In standard situations, the border of the roughened titanium surface is located either at the bone crest or slightly below (∞1 mm). Next, the appropriate healing caps are selected. In most cases, a 1.5 mm or a 3 mm healing cap is utilized. This selection depends on the clinical soft tissue situation. Wound closure for a non-submerged healing is initiated by a precise and tension-free adaptation of the mucosal margins to the implant post or healing cap. When necessary, the utilization of small releasing incisions or small pedicle flaps is recommended. A fine atraumatic suture material (size 4–0 or 5–0) is utilized. When keratinized mucosa is lacking, soft tissue grafting may be necessary to re-establish a sufficient band of keratinized mucosa. Usually, a postsurgical radiograph is taken to control the implant position and implant direction. In addition, a postsurgical radiograph can be indicated for forensic reasons. Post-operative treatment and healing periods During the soft tissue healing period of 2–3 weeks, chemical plaque control with chlorhexidine-digluconate (0.12%) is recommended. Mechanical toothbrushing is abandoned in the surgical sites for at least 2 weeks. Follow-up visits are scheduled after 7, 14 and 21 days with clinical examination and wound cleaning. The sutures are removed after 7–10 days. The healing caps should be exchanged – when really necessary – at the earliest after 3 weeks. The bone healing period for ITI implants with a TPS surface has progressed sufficiently after 3– 4 months, as outlined in chapter 3, allowing the insertion of the appropriate abutment and the initiation of the prosthetic treatment. During the bone healing period, functional loading of the inserted implant by provisionals such as partial dentures should be avoided. The status of the integrated implant is evaluated by clinical examination and a periapical radiograph. As already mentioned in chapter 3, the utilization of SLA implants allows a further reduction of 87

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Fig. 5.5 Text, see next page.

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Buser & von Arx the healing period. An ongoing multicenter study has successfully tested a healing period of 6 weeks for implant sites with normal bone density (class I–III) in fully and partially edentulous patients. The preliminary results are promising, with success rates exceeding 98% at the completion of the healing period, and will be published in the near future (Cochran et al. 2001). The surgical procedures in non-esthetic sites are demonstrated with four case reports (Figs 5.5–5.8). Implant placement in esthetic sites General remarks Esthetic sites for implant therapy are primarily located in the anterior maxilla, including the first premolar sites. Main indications are single-tooth replacement with implant-borne crowns and the rehabilitation of extended edentulous spaces with implant-supported multiple crowns or a FPD (Table 5.3). The primary treatment goal is the reestablishment of esthetics and function. These indications are demanding for the implant surgeon, since anatomical and surgical aspects are at least as important for a satisfying treatment outcome as prosthetic and technical aspects. The details of prosthetic treatment planning and therapy in esthetic sites are outlined in chapter 8. The following section will discuss the surgical aspects of how esthetically pleasing implant restorations can be achieved with ITI implants on a predictable level. The surgical aspects important for optimizing esthetic implant restorations include (a) implant insertion in an optimal three-dimensional position (‘‘restoration-driven implant placement’’, Garber & Belser 1995), and (b) the achievement and maintenance of esthetic soft tissue contours (Table 5.4). A correct three-dimensional implant position includes a correct vertical location of the implant with a subgingivally located implant shoulder to avoid a visible cervical metal margin. In cases with a high lip line, a visible metal margin is unacceptable nowadays and represents an esthetic failure of implant therapy. Thus, ITI implants are utilized as submerged implants in esthetic sites by inserting them approximately 2 mm deeper into the hard and soft tissues when compared to standard nonesthetic implant sites (Buser & Belser 1995). The deeper placement of ITI implants into the bone leads to an increased crestal bone resorption, as demonstrated in experimental and clinical studies (Ha ¨ mmerle et al. 1996; Hermann et al. 1997). The latter study in the canine mandible clearly demonstrated that the vertical position of the implant shoulder with its microgap at the implant-abutment connection has a significant impact on crestal bone resorption. A distance of 1.5 and 2.0 mm between the first bone-implant contact and the microgap at the implant shoulder has been consistently observed. These dimensions seem to be quite constant and are part of a biologic width observed not only around natural teeth (Gargiulo et al. 1961), but also around dental implants (Cochran et al. 1997). Hence, the deeper an implant is inserted into the bone, the more bone will be resorbed for a submerged implant following the second-stage procedure with abutment connection. This bone resorption is not a pathological condition but a physiological reaction to the implant placement. In order to limit the amount of bone resorption, esthetic plus ITI implants are recommended for these indications, since surface properties also influence the bone reaction following implant placement (Buser et al. 1992a; Hermann et al. 1997). Esthetic plus implants have a ‘‘sprayed-up’’ TPS surface, and the height of the smoothly machined neck is reduced to 1.8 mm. Therefore, it is recommended that the deeper implant placement should be done according to the principle ‘‘as much as necessary, as little as possible’’. An extremely deep implant placement has clear disadvantages, such as an unfavorable lever-

Fig. 5.5. a. Occlusal view of a distal extension situation in the left mandible. b. Status following a midcrestal incision and elevation of two full-thickness flaps. The smoothened alveolar crest is sufficient in width for a standard implant placement. c. After the implant position is marked with a round bur, the first bone preparation is made with spiral drill .1 (ø 2.2 mm). d. The bone preparation is increased with the spiral drill .2 (ø 2.8 mm). e. The entrance of the bony implant bed is further opened up with the small profile drill. f. The final preparation is made with the spiral drill .3 (ø 3.5 mm) to a sink depth of approximately 10.5 mm. g. The occlusal view demonstrates the three bony implant beds with intact buccal and lingual bone walls. h. Due to the medium bone density (class II–III), tapping is only performed in the coronal portion of the implant bed. i. The placement of the SLA implant is performed with the insertion device and the surgical adapter at 15 rpm. The microrough SLA surface is inserted slightly below the bone crest on the approximal aspects. j. 3 mm healing caps are inserted to extend above the soft tissue level. k. A tensionfree and precise soft tissue adaptation is followed by wound closure with fine interrupted sutures (4–0 or 5–0). l. The clinical status at day 7 showes a normal soft tissue healing. The sutures can be removed. m. The healing period is completed at 6 weeks following implant placement. Note the excellent soft tissue healing around the 3 SLA implants. n. Conical abutments are inserted at 35 Ncm to initiate the restoration with a provisional FPD. o. Periapical radiograph at 3 months following functional load with a provisional restoration. The bone crest levels are excellent. p. Periapical radiograph at 12 months demonstrating the final ceramometal restoration and stable bone crest levels.

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Fig. 5.6. a. Distal extension situation with two ITI implants placed in the premolar sites. The patient wants to have a third implant in the first molar site. b. Clinical status following implant placement and suturing of the mesial papilla. The wound margins are carefully adapted to the healing cap without gingivectomy. Two small relieving incisions are made to allow the rotation of the wound margins distally to the implant. c. The mucosa margins are rotated and sutured with an interrupted suture. d. Clinical status 3 months following placement of the ITI implant with a TPS surface.

age arm between clinical crown and implant length, an increased probing depth in approximal areas (±5 mm), a microgap inaccessible for hygiene, and increased crestal bone resorption, as outlined above. The correct implant placement in orofacial position significantly influences the profile of the superstructure. In particular, the point of emergence from the soft tissues determines the final cervical contour of the restoration. Generally, a proper emergence profile is desirable, both for esthetic and hygienic reasons. Therefore, the vestibular aspect

of the implant shoulder has to emerge as buccally as do adjacent natural teeth. In addition, a buccal bone wall of at least 1 mm thickness should be present when the implant is inserted. A proper orofacial implant position is difficult to obtain when a buccal atrophy of the alveolar crest is present. In such cases, bone reconstructive surgery is needed to locally augment the alveolar process, either prior to or simultaneously with implant placement (Buser et al. 1992b, 1996; von Arx et al. 1998; von Arx & Kurt 1998). The third aspect to be mentioned in this context 91

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Fig. 5.7. a. Distal extension situation in the right mandible. Status following preparation of two implant beds. Note the intact buccal and lingual bone walls of sufficient thickness. b. The buccal flap was released with a distal incision of the periosteum to allow a precise and tension-free adaptation to the healing caps. With this technique, no gingivectomy is necessary to achieve a close adaptation of the mucosa. c. Clinical status at 6 weeks with an excellent soft tissue healing. The two SLA implants are ready for prosthetic restoration. d. Two conical abutments are inserted at 35 Ncm for a cemented implant restoration. e. Clinical status at the 2-year follow-up visit. The periimplant soft tissues show no clinical signs of inflammation. f. Periapical radiograph at 2 years indicates stable bone crest levels around both SLA implants.

is the implant axis, which determines the access for the occlusal screw. Unfortunately, a discrepancy between the potential implant axis and the clinical crown axis is often encountered in the anterior maxilla due to the anatomy of the alveolar process. Therefore, the use of a horizontal screw path for a 92

screw-retained single crown is recommended (Belser & Buser 1997). The achievement and maintenance of esthetic buccal soft tissues is of utmost importance for an esthetic implant restoration. Esthetic soft tissue contours include a harmoniously scalloped gingival

Surgical procedures in partially edentulous patients

Fig. 5.8. a. Distal extension situation in the left maxilla. Status 8 months following a sinus grafting procedure. Three SLA implants can be inserted. b. Small relieving incisions are applied on the buccal wound margin to allow small rotational flaps to be placed in the interimplant spaces. c. The small flaps are rotated. The margins are stabilized with interrupted sutures. d. Clinical status 1 week following implant placement. The wound shows some signs of secondary wound healing in the interimplant spaces. The sutures can be removed. e. At 2 weeks, wound healing has progressed further. f. At 8 weeks, the clinical status shows excellent peri-implant soft tissue conditions. The SLA implants are ready for provisional restoration with three splinted crowns.

line, the avoidance of abrupt vertical changes or differences in clinical crown length between adjacent teeth, a convex buccal mucosa of sufficient thickness, and distinct papillae (Belser et al. 1996b; Belser et al. 1998). Thus, careful soft tissue handling by the implant surgeon is important, including an appropriate incision and wound closure technique. In particular, a submerged implant placement is recommended in esthetic sites. In addition, soft tissue grafting is quite often necessary

in esthetic sites to improve the esthetic treatment outcome. Stable soft tissue conditions can primarily be achieved with the presence of a buccal bone wall of at least 1 mm at the time of implant placement to facilitate bony support of the buccal soft tissues. Thus, no compromise should be made by the implant surgeon concerning a sufficient crest width (implant diameter π 2 mm) when the implant is inserted. There is clinical evidence that the lack of this bone wall can cause soft tissue prob93

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Fig. 5.9. Text, see next page.

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Fig. 5.9. a. Single-tooth gaps in the anterior maxilla due to a traumatic tooth loss. b. The implant surgery is initiated with a palatal incision for a full-thickness flap. c. The flap is elevated with divergent relieving incisions. The bone crest is smoothened with a bone scalloping procedure. Approximal bone is not touched at all. d. Status following preparation of the implant bed. Note the intact buccal bone wall of at least 1 mm thickness to serve as soft tissue support. This buccal bone is crucial for a stable esthetic treatment outcome. e. The implant is inserted to a correct vertical level. The implant shoulder is located slightly apical to the cej-level of adjacent teeth. f. The orofacial position of the implant shoulder is ideal. The point of emergence is comparable with those of adjacent teeth. g. A healing cap with a buccal bevel is inserted. h. A free connective tissue graft is harvested in the left palate to improve the soft tissue thickness and contour on the buccal aspect of the implant. i. The graft is placed in situ to check the shape and the position. j. The graft is sutured to the buccal flap to ensure correct position and an intimate contact with the vascularized buccal flap. k. A tension-free wound closure is achieved following the incision of the periosteum. The wound margins are secured with interrupted sutures (4–0 or 5–0). l. The existing partial denture is shortened and put in place. m. Clinical status at 8 weeks. Note the convex soft tissues with an excellent contour and color. The site will now be reopened to gain access to the integrated implant. n. Status following placement of a long healing cap to configure the soft tissue channel to the implant shoulder. o. The peri-implant soft tissues are nicely healed two weeks following gingivectomy. p. Restoration with a provisional crown to get an optimal soft tissue conditioning. q. 3 months later, the peri-implant sulcus has been nicely formed. r. Restoration with a screwretained ceramometal crown. s. Esthetic treatment outcome. t. The periapical radiograph at 3 years indicates a stable bone crest level with a steady-state situation.

lems such as gingival recessions or an increased failure rate for dental implants (Lekholm et al. 1986; Dietrich et al. 1993). In addition, appropriate oral hygiene has to be performed by the patient to establish and maintain a healthy peri-implant mucosa. Preoperative examination in esthetic sites Clinical evaluation During preoperative examination, the implant sur96

geon must primarily evaluate the anatomical aspects of the potential implant site. This includes a variety of parameters such as the shape and width of the bone crest, the absence or presence of a buccal undercut, the status of neighboring teeth (caries lesions, existing fillings or crowns, discolorations, etc.), the mesio-distal width of the edentulous space, the intermaxillary situation (a deep bite can cause problems), the absence or presence of diastemas, the thickness and contour of buccal soft tissues, the position of papillae, the quality of

Surgical procedures in partially edentulous patients
Table 5.3. Indications in esthetic sites O Single-tooth gaps in the anterior maxilla O Extended edentulous spaces in the anterior maxilla

Table 5.4. Surgical aspects to optimize implant esthetics O Optimal three-dimensional implant position (‘‘Restoration-driven implant placement’’) – Subgingival implant shoulder – Correct orofacial implant position – Appropriate implant axis O Achievement and maintenance of esthetic soft tissue contours – Harmoniously scalloped gingival line – Intact papillae – Convex buccal soft tissues of sufficient thickness

tooth replacement of missing lateral incisors if the mesio-distal width of the gap is limited (5.0–6.5 mm). In general, esthetic plus implants are predominantly used with a sprayed-up TPS surface to limit postoperative bone resorption in the crestal area due to the deeper implant placement, as discussed in detail above.

the gingival tissues (phenotype I or II), and the location of the smile line (high vs low lip line). In single-tooth gaps, a minimum mesio-distal width of 6.5–7.0 mm is necessary for the placement of a standard screw implant (S 4.1), whereas a narrowneck implant (NN 3.3) requires a minimal width of 5 mm. Radiologic evaluation In standard cases, a periapical radiograph and/or a panoramic radiograph is sufficient. Tomograms or CT scans are only indicated in special situations, such as to evaluate the need for bone augmentation procedures in patients presenting with bone defects. Selection of implant type and length As already outlined in chapter 3, the longest possible implant is selected up to a maximum of 12 mm (Ω14 mm sink depth). The implant of first choice is the standard screw implant (S 4.1). The narrowneck implant (NN 3.3) is often used for the single-

Surgical procedure in esthetic sites The surgical procedure used for implant placement in esthetic sites is summarized in Table 5.5. Following local anesthesia, the mucosa is opened with a crestal incision located slightly on the palatal aspect. This assures a sufficient vascularity of the buccal flap in the papillary area. The incision is extended through the sulcus of adjacent teeth to the buccal and palatal aspect of the alveolar crest. Buccal relieving incisions are only made when necessary. Subsequently, the buccal and palatal mucoperiosteal flaps are elevated with a fine tissue elevator to guarantee low-trauma soft tissue handling. This is followed by an intrasurgical site analysis to evaluate the crest width and the buccal aspect of the alveolar crest. As outlined in chapter 3, a minimal crest width of 5.5 mm is required for the placement of a standard screw implant. A crest flattening as bone scalloping procedure is recommended, since this facilitates easier and more precise preparation of the implant bed. The surgeon should not remove any bone in the approximal area of adjacent teeth, since this bone is important for the support and maintenance of the papillae. The precise position of the implant is marked with small round burs. The utilization of surgical guides is recommended in the case of multiple missing teeth, whereas landmarks of adjacent teeth provide sufficient guidance in most cases with a single-tooth gap. The preparation of

Table 5.5. Surgical procedure for implant placement in esthetic sites (new protocol for ITI implants with SLA surface) O O O O O O O O O O O O O O O O Crestal incision, slightly palatal Buccal relieving incisions only if necessary Crest flattening as bone scalloping procedure; bone in the approximal area of adjacent teeth is not touched! Surgical guides are recommended in cases with multiple missing teeth Preparation of implant bed with spiral drills with increasing diameter Sink depthΩimplant length π 2 mm Use of a profile drill to open the entrance of the bone cavity to allow a deeper implant insertion (approximately 2 mm deeper than in standard sites) Tapping in sites with normal bone density, no tapping in sites with spongy bone Implant insertion with the premounted insertion device using a slow speed of approximately 15 rpm Tapping and implant insertion can be done with a hand ratchet or with an adapter attached to a special contra-angle handpiece Utilization of esthetic healing caps with a buccal bevel In case of a thin buccal mucosa and/or a concave buccal soft tissue contour, the utilization of a connective tissue graft is recommended Precise positioning of the buccal wound margin, in particular of the papillae Primary wound closure with tension-free suturing to achieve a submerged healing of the implant Reopening procedure with a mucosaplasty after 6 weeks to gain access to the implant Initiation of prosthetic treatment at 8 weeks

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Buser & von Arx the implant bed is carried out with standard spiral drills of increasing diameter (2.2 mm, 2.8 mm and 3.5 mm). This technique reduces the trauma to the bone tissue, and gives the surgeon a chance to change the direction of the implant axis – when necessary – between the different drill steps. As already outlined above, a deeper implant placement is recommended in esthetic sites. As a rule of thumb, the implants are inserted approximately 2 mm deeper than in standard sites. Hence, the implant bed is prepared to 14 mm if a 12 mm implant is planned to be inserted. As a consequence of an esthetic implant placement, the entrance of the bone cavity has to be prepared with the profile drill to allow a deeper implant insertion. In addition, Esthetic plus implants are most often utilized to limit the amount of bone resorption in the crestal area. During the different steps of the bone preparation, the availability of different depth gauges helps the surgeon control the future implant position in a horizontal and vertical direction as well as the implant axis. Prior to implant placement, the tapping of the thread is done in all sites with normal bone density (class I–III). In cases with extremely spongy bone (class IV), no tapping should be carried out, in order to improve the primary stability of the implant. Tapping and implant insertion are done either with an adapter attached to a special contra-angle hand-piece (at 15 rpm) or with the hand ratchet. Implant placement has recently been further simplified, since the new ITI insertion device is premounted onto the implant, allowing a non-touch handling of the implant from the sterile ampoule. Following implant placement, the horizontal and vertical position of the implant shoulder as well as the primary stability of the implant are carefully checked. The next step is to select the appropriate healing cap. An esthetic healing cap with a buccal bevel is recommended to reduce the volume of the cap in the critical zone of the buccal soft tissues. This cap is available in two heights (2 and 3.5 mm) and has the clinical advantages that it will (a) fully cover the implant shoulder, (b) support the soft tissues in the approximal area, and (c) preshape a part of the transmucosal soft tissue tunnel to the implant already during the initial healing period. Furthermore, in the case of a thin buccal mucosa and/or a concave buccal soft tissue contour, the soft tissues are corrected with a grafting technique at the time of implant placement. This surgical concept is straightforward and eliminates an open-flap procedure at the second-stage surgery. In routine cases, a connective tissue (CT) graft is sufficient to improve the thickness and contour of the buccal mucosa. These grafts are easily harvested in 98 the premolar area of the palate. With buccal relieving incisions, the CT graft is sutured to the periosteum of the mucoperiosteal flap to avoid displacement of the graft during wound closure. Prior to the completion of the surgical procedure, the buccal flap, and in particular the papillae, is precisely repositioned. The surgeon should aim for a precise and tension-free primary wound closure to allow submerged implant healing on top of the applied esthetic healing cap. Fine atraumatic suture material (4–0 or 5–0) is recommended. Following surgery, a periapical radiograph is taken to examine the position and direction of the inserted implant and its relationship to the roots of adjacent teeth. The existing provisional partial denture is shortened in the edentulous area to avoid precontact of the prosthesis with the soft tissues during initial wound healing. Postoperative treatment Postsurgical treatment in an esthetic site does not differ from that in non-esthetic sites. Chemical plaque control with chlorhexidine-digluconate (0.12%) is recommended in the first 2–3 weeks following implant placement. Suture removal is scheduled after 7–10 days, and further clinical exams are made on days 14 and 21. At day 14, instruction on proper hygiene is given to facilitate an optimal wound healing period. Reopening with a mucosaplasty After 8–10 weeks of healing, a local mucosaplasty is performed to uncover the integrated implant. This is done with a 12d blade to gain access to the implant shoulder. Electrosurgery is contraindicated. The esthetic healing cap is replaced by a long extension healing cap (3 mm or 4.5 mm) to finally shape the transmucosal soft tissue tunnel to the implant shoulder. The soft tissue margins should not be compressed too much, which is indicated by a severe and lasting blanching of the mucosa. Abutment insertion After 12 weeks of healing, the abutment is inserted and the impression is taken to initiate the prosthetic treatment. In standard cases, the octabutment is selected for a screw-retained restoration (see chapters 6 and 8). The status of the integrated implant is evaluated by clinical examination and a radiograph. Usually, implant loading is initiated after 3 months of healing. As already mentioned above, the introduction of the new SLA surface offers a further reduction of

Surgical procedures in partially edentulous patients the healing period to six weeks in sites with normal bone density (class I–III). In esthetic sites, however, the time for soft tissue healing and soft tissue maturation following implant placement and the reopening procedure has to be respected to achieve stable esthetic soft tissues. The reopening procedure is scheduled at 6 weeks of healing to gain access to the integrated SLA implant. At 8 weeks, functional loading is initiated with a provisional, screw-retained crown. The surgical procedure is demonstrated with a case report (Fig. 5.9). References
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