3: Implants for the maxillary edentulous patient

Implants for the maxillary edentulous patient

image Additional illustrations can be found on the companion website at www.blockdentalimplantsurgery.com

Preoperative planning and assessment

Implant-supported therapy for the patient with an edentulous maxilla depends on several treatment planning issues. The following factors determine the treatment of choice.

1. General health of the patient

Debilitated patients often have soft bone and do not heal as well as healthy patients. Patients with diabetes with sugar levels above 120 mg/dL may not form bone on implants as well as those in better control.1-5 Female patients older than age 50 years and older men may have low bone density, which must be taken into consideration and evaluated preoperatively by examining the bone density in the jaw.

2. Goals of the patient, such as the need for removal of the palatal portion of the prosthesis, increased stability when chewing, and desire for a fixed prosthesis

3. Esthetic requirements to restore the soft tissue profile of the patient

4. Availability of bone in the anterior and posterior maxilla

5. Financial considerations

6. Consent for bone grafting of deficient sites, including consideration of the morbidity of the harvest site

Treatment planning usually may be initiated in the office of one of the members of the treatment team. It involves establishing the patient’s goals regarding what he or she wants at the completion of implant therapy. After these goals have been established by the surgeon, an assessment of bone availability is performed.

A traditional panoramic radiograph is not accurate and does not reveal cross-section ridge width and height information. The traditional panoramic radiograph is difficult to use to appreciate and diagnose sinus pathology. A cone- beam scan is critical for accurate assessment of the bone in the maxilla. The scan is taken as a screening tool using a low-resolution 10 cm × 0.4 voxel setting. This radiation dose approximates 2.4 panoramic images. New cone-beam machines are decreasing the radiation dose delivered to the patient, which is very important to consider patient’s long-term health. From this scan, the following can be assessed:

1. Condylar morphology to rule out erosion and vertical dimension problems

2. The mandibular plane angle can be appreciated, indicating the patient’s vertical dimension and presence of overclosure of the mandible because loss of posterior occlusion or loss of bone.

3. The skeletal position of the maxillary ridges in regards to the mandibular ridge or teeth

4. The status of the sinuses, including ethmoid, frontal, sphenoid, and maxillary. The presence of intrasinus polyps, congestion, or other pathology can be easily identified and treatment planned accordingly.

5. The thickness of the alveolar bone in all areas of the maxilla. In addition to thickness, the presence of bone on the piriform rim can be discerned. The quality of the bone can be determined.

6. The location of the incisive canal is easily seen.

7. By combining the cone-beam scan with computed tomography (CT) planning software, the need for bone reduction can be determined and a model made if necessary. The specific implant diameter and lengths can be determined. The type of abutments can be determined. CT surgical guide stents can be fabricated, as well as a milled acrylic prosthesis of the provisional prosthesis for simple prosthesis conversion.

The anterior maxilla consists of the area anterior to the lateral walls of the nose or the anterior border of the sinus. The posterior maxilla consists of the regions of the second premolars and molars. The following four conditions are considered:

A prosthetic plan is completed, with the aid of the restorative dentist, after the amount of bone has been determined. Parel’s classification of the edentulous maxilla is useful for conceptualizing the prosthetic plan (Box 3-1).

For the class I maxilla, a fixed implant-borne restoration can be fabricated because the patient has adequate alveolar bone to support the soft tissues and is missing only the teeth. Usually greater than 10 mm of bone height is present in both the anterior maxilla and the posterior maxilla. For a fixed crown and bridge restoration, implants need to be placed within the confines of the teeth of the planned restoration. In addition, implant placement should avoid excessive angulation to ensure that the implants can draw as a single unit. Placement should avoid the embrasure regions to promote an esthetic outcome and oral hygiene. Finally, the implants should be placed 3 mm apical to the gingival margin of the planned restoration to allow the restorative dentist to develop a natural emergence of the crowns from the gingiva. A well-made, detailed surgical template is essential for a fixed crown and bridge restoration. The template should have full palatal coverage with anatomic retention at the hamular notches in the posterior maxilla, enabling the stent to be placed in a repeatable, stable, and accurate position that allows the surgeon to follow its prescription when placed into the mouth.

If the patient with a class I edentulous maxilla desires a tissue-borne overdenture on four implants because of financial constraints, the overdenture bar must avoid an excessive space-occupying design because the patient is missing only teeth and not alveolar bone.

The class II maxilla can be managed esthetically with a fixed crown and bridge prosthesis. However, this class may require a small amount of pink material as a labial flange to support the nasolabial soft tissues and to avoid the appearance of the interface between the prosthesis and the ridge when the patient smiles because of lip movement. There is usually a need to add pink gingival restorative material to provide the esthetic appearance upon smiling.

A useful technique for determining the need for acrylic to support the soft tissues is to duplicate the patient’s maxillary dentures and remove the labial flange, leaving only the teeth. The resultant soft tissue profile with the modified duplicated maxillary denture can help the implant team and the patient decide on the treatment plan. In addition, a deficiency of alveolar bone necessitates the placement of implants more apical than is ideal, resulting in excessively long teeth. The restorative solution is to create teeth with pink acrylic, a removable lip “plumper,” or a hybrid type prosthesis with space between the prosthesis and implants.

For the class 2 maxilla, a fixed crown and bridge prosthesis, a fixed-removable (e.g., spark erosion or milled) prosthesis, or a type of removable overdenture prosthesis may be prescribed. The fixed implant-borne and fixed-removable prostheses require at least six to eight endosseous implants to support a maxillary implant-borne prosthesis. Cross-arch stabilization is recommended, especially if the opposing occlusion includes natural teeth or has limited mandibular posterior teeth. Zygomatic implants are the exception (see Chapter 5). These traditional fixed or fixed-removable prostheses require posterior maxillary vertical bone height for implants placed in the first molar region, or the patient should have adequate bone to angle the most posterior implant to provide the abutment at the first molar location. Cantilevers are not recommended in the maxilla. The removable tissue-borne prosthesis requires four implants placed into the anterior maxilla to support a bar, which has retentive vertical stress-breaking attachments. Edentulous maxillary prostheses usually are fabricated with cross-arch stabilization of the left and right implants. Using four individual implants with studlike attachments is financially less expensive, but long-term clinical data are not available for evidence-based support for this treatment plan.

For patients who smoke, consume excessive alcohol, or have uncontrolled diabetes or other systemic diseases that prevent bone grafting, the surgeon’s preferred option for placing implants is to use the available bone and avoid grafting. After a discussion with the restorative dentist, the amount and location of available bone can be determined.

Placement of four implants into the anterior maxilla

For a patient with adequate anterior vertical bone height and a treatment plan for anterior implants to provide overdenture support, four implants can be placed. Placement of at least four implants is recommended for an implant-supported overdenture in the maxilla because fewer than four maxillary implants will not predictably resist the forces6 placed on them (Figure 3-1). Two implants are contraindicated to retain a maxillary overdenture.

Preoperative radiographs and a physical examination reveal the height and thickness of the alveolar ridge. Four implants in the anterior maxilla, often combined with vertical stress-broken attachments placed at the distal aspects, are used to support a rigid bar. The anterior maxillary implants should be placed within the confines of the borders of the planned prosthesis and not labial to the borders of the teeth. The implants should be placed to avoid impingement of the teeth in the overdenture and to allow space for fabrication of the bar. Careful attention to the position of the incisal edges of the lower teeth provides important information and prevents conflicts of space between the lower teeth and the palatal portion of the overdenture and the underlying bar.

At surgery, the surgeon should understand the prosthetic plan and recognize the ideal locations of the implants. Often these implants can be placed slightly palatal to the crest to engage more of the palatal bone, providing a thicker width of labial bone (see Figure 3-1). A local anesthetic is infiltrated into the labial and palatal regions of the anterior maxilla. Incisions for implants placed into the anterior maxilla usually are placed over or slightly palatal to the crest. Vestibular incisions are avoided in the anterior maxilla because they can shorten the vestibule and increase the patient’s postoperative discomfort.

The incision is made along the crest, moving labially around the incisive papilla to avoid transecting its contents, and carried to bone through the periosteum. A full-thickness mucoperiosteal flap is raised, with care taken to prevent trauma to the flap. If necessary, vertical release incisions can be made distal to the planned implant locations to help raise the flap superiorly and thus expose the facial aspect of the maxillary bone. An anterior midline release is not used; it would increase postoperative morbidity because of the disturbance in the anterior lip musculature.

A full-thickness palatal reflection is then accomplished. The contents of the incisive canal are preserved and not incised. The palatal reflection should allow visualization of the slope of the vertical palatal bone to ensure that the surgeon can visualize the insertion of the implants without violating either the labial or the palatal cortical bone, thereby keeping the implant body within bone. The use of cone-beam scans allows less reflection of the palatal and labial tissues because the bone contours are determined from the scan. The surgeon can reflect only sufficient tissue for orientation and proceed with placing the implants with less morbidity for the patient. With the advent of angled abutments, the surgeon can place the implants between the palatal and labial cortical bone, with greatest primary implant stability. This avoids common facial bone dehiscence from attempting to place all of the implants parallel. The abutments, which are angle corrected, provide for parallelism and draw when impressions are taken and for bar retention.

After the labial and palatal tissues have been reflected, the surgeon should have a good view of the crestal bone thickness and the contours of the palatal and facial cortical bone. If necessary, the dissection can be extended superiorly to identify the piriform rim, especially for the more atrophic maxilla. The thickness of bone is confirmed, and the surgical stent is placed. The areas of planned implant placement are examined.

Often the crest of the maxilla is narrow and widens within a few millimeters of the crest. Specific sites may be wider than others, indicating a site that is more ideal for the implant when bone bulk is considered. However, before placing the implant in a site slightly different from that prescribed by the surgical stent, the surgeon should ensure that the prosthetic plan would not be adversely affected.

Because the maxillary crest usually has sharp edges and slopes, the first step is the creation of a depression in the ridge that allows accurate engagement of the drills. The implant sites are scored with either rongeur forceps or a round bur, creating a divot into the bone. The round bur is used to initiate the osteotomy site and to determine the specific location of the implant in the middle of the crest. Accurate placement of this round bur hole is important because subsequent drills will start in this round hole. Changing the position of the implant entry location may be difficult after the drilling process has started. If the first drill needs adjustment in position (e.g., the hole is too far labial or palatal), the round bur is used to relocate the hole slightly palatal, labial, distal, or mesial, guided by the need to place the implants into adequate bone and in the correct location. The surgeon must always critically examine the implant sites. The implants must be placed accurately to ensure successful prosthetic treatment.

Subsequent graduating-sized drills initiate and expand the implant site until the final drills are used. If the ridge is excessively narrow, the ridge may require grafting before implant placement. Usually the ridge has sufficient width for placement of the implants. If the ridge is thin and does not expand as the bone is examined superiorly, the use of osteotomes or ridge splitting in a ridge less than 3 mm is not predictable. For these cases, onlay grafting is indicated and should be discussed with the patient. (See Chapter 4 for examples of onlay grafting of the anterior maxilla.)

Implants for overdentures typically are placed with their centers slightly palatal to the crest to avoid dehiscence and thin bone over the facial aspect of the implants. The incisive canal should be avoided as a site for implant placement. Implants should be placed to prevent dehiscence of the implant within the incisive canal. Specifically, implants for overdentures are placed in the canine and premolar locations, depending on the availability of bone. An implant can be placed in the lateral incisor position if necessary. However, implants placed in the central incisor locations complicate the prosthetic rehabilitation because the presence of the abutments and bar near the midline may result in excessive palatal bulk in the denture. This outcome may be bothersome to the patient.

If a dehiscence of bone occurs in the midportion of the implant because of concavity of the ridge, particles of bovine xenograft, which is clinically slow to nonresorbable, are placed to obliterate the defect. Use of a membrane depends on the surgeon’s clinical judgment. In general, a membrane is not necessary for small dehiscences.

After the implants and the implant cover screws have been placed into the implant bodies, the incision is closed. Occasionally, the periosteum must be released to allow tension-free closure. If no graft has been placed, the type of suture depends on the clinician’s preference.

To avoid pressure trauma to the incisions and implant sites, the patient’s denture should be left out of the mouth for 7 to 10 days after implant surgery. However, if the patient cannot accept this recommendation, the surgeon or restorative dentist should remove the labial flange to the gingival margin of the denture teeth and relieve the crest region. This extremely relieved maxillary prosthesis can be retained with denture adhesive dotted on the palate without adhesive on the incision sites. Patients can wear the modified prosthesis for esthetic reasons, but they must consume a liquid, pureed diet for 2 weeks.

Exposure of implants in the edentulous maxilla

After an appropriate amount of time has been allowed for implant healing, the patient returns for exposure of the implants and placement of temporary healing abutments (Figure 3-2). After administration of a local anesthetic, an incision is made bisecting the keratinized gingiva (KG) to transpose it labial to the implant abutments. The mucosal flap is reflected full thickness, including periosteum, to allow direct visualization of the implant. The cover screws are removed, the top of the implant is gently cleansed of soft tissue, the inside of the implant is irrigated with sterile solution, and the temporary healing abutment is placed. The gingival flap may be excessively thick and may need to be thinned. The inside thickness of tissue is removed with a scalpel to thin the flap, which is reduced as necessary. The incision is closed around the healing abutments. The denture is relieved and relined to stent the mucosa to the alveolus (see Figure 3-2).

Placement of anterior and posterior implants without a graft

If the patient’s goal is to have a denture that accommodates a palateless prosthesis, enabling the patient to chew all textured foods without the palate covered, a sufficient number of implants is required to resist the forces of mastication. For this section, it is assumed that patients have sufficient anterior and posterior bone for implants from molar to molar. These patients may have had sinus augmentation to restore vertical bone for implant placement. They may represent patients who had all of their teeth removed with socket grafting with maintenance of bone volume.

For the patient with bone available from molar to molar across the arch, six to eight implants for a fixed implant-supported or removable prosthesis is recommended, with an adequate number of implants located posteriorly to support the molars.

An edentulous patient with a class I maxilla requires only the placement of implants to replace the missing teeth (Figure 3-3). In most patients with a class I maxilla, who have lost their teeth with minimal bone loss, the labial bone has an irregular contour. These patients may benefit from augmentation of the labial bone to smooth the bone contour and enhance the final restoration, especially for those with high smile lines.

Patients with a class II maxilla, who have lost their teeth but have a moderate amount of bone, must have an esthetic evaluation as described previously. Determination of lip support is important. These patients should be advised that pink restorative material may be necessary for soft tissue support. These patients may require a labial flange of a removable prosthesis to provide nasolabial support. Conversely, they may need material added to a fixed restoration to provide an esthetic facial appearance. Either way, this needs to be determined before implant placement. Maxillary hybrid type prostheses rarely require additional flange support because of the bulk on the labial portion of the fixed prosthesis. With the use of maxillary hybrid prostheses and better pink restorative materials, more fixed options are available, resulting in less use of fixed removable prostheses. The cost of these fixed prostheses is always important to consider but is not preventive for many patients (Figure 3-4).

Patients with a class III maxilla, who have lost their teeth and most of the alveolar bone to the basal level, can benefit from a fixed or a fixed-removable restoration, depending on bone height and availability (see Figure 3-4). If implants are angled, then their length increases, increasing the mechanical stability, and hence more fixed options become available. The use of angled abutments restores parallelism for the restorative phase.

When placing implants for a fixed restoration, virtual planning before implant surgery provides accuracy of the implant selection and assurance that the implants can be placed in an ideal location. The clinicians have two options for virtual planning.

One option is for placement of virtual teeth on a cone-beam scan of the edentulous ridge, which provides information on potential teeth and implant positions. This is useful when new dentures are not available and the patient wishes to avoid more radiation using a dual-scan approach. A second option is to use a new denture with fiduciary markers in the palatal and labial flanges and a dual scan method to plan the case. The use of an acrylic prosthesis with no radiopaque material allows for a mask of the prosthesis to be made on the computer and overlaid on the edentulous ridge. The prosthesis can be removed with one click to allow for visualization of virtual implant placement and its position in the bone.

A CT-generated drill guide can be fabricated, a duplicate of the denture can be used to guide implant placement, or no guide can be used. The CT-generated guide allows for accurate placement with minimal flaps; thus, the patient has less postoperative morbidity. The drill guide can also be used to place implant analogs in the master cast to prepare abutments and fabricate a provisional restoration prior to surgery. There are additional costs involved, but when considering the costs of multiple implants as well as the cost of the fixed restoration, the additional cost of CT-generated guides and model surgery is a small percentage of the total treatment cost and is well accepted by the patient.

The duplicated, clear acrylic denture is used to mark the vertical bone position necessary for a hybrid prosthesis. It is also used to identify implant position along the crest. For a fixed restoration using crown and bridge techniques the teeth positions can be identified to allow placement of the implants under the teeth rather than in embrasures. Abutments can be chosen using the virtual implant position relative to the planned prosthesis. The duplicated denture is not expensive to fabricate and provides excellent reference for final esthetics. Full palatal coverage should be left on the duplicated denture to allow for stability when it is used.

If no guide is used, there may be error. The surgeon needs to recognize that poor implant positioning results from poor preparation. If the patient is having a significant implant restorative plan, then the surgeon must take responsibility to have proper preoperative planning accomplished.

When there is sufficient bone anterior and posteriorly, a fixed restoration can be planned. There are generally two options for implant placement. One option is placement of implants in the molar and premolar locations bilaterally for right and left three-unit fixed bridges. Additional implants are placed in the canine and central incisor locations bilaterally for a six-unit, four-implant retained prosthesis. This plan does not provide cross-arch stabilization, which may also result in adverse mechanical stresses.6

A second option is to place implants from canine posteriorly in the canine, premolar, and molar sites for four implants for each side, leaving the anterior maxilla void of implants. A full arch single unit restoration is fabricated. This provides the patient with a cross-arch stabilized restoration, which has been shown to be stable long term. Lateral forces from occlusion are absorbed by the full arch framework with less tension and compression felt on the implant as described in the Skalak model.6 If three units are made for a full arch restoration, lateral forces may not be absorbed as efficiently. If necessary, the full arch restoration can be screw retained for maintenance or cemented with temporary cement for removal.

If a bar type restoration is planned, six implants are placed with the distal implant exiting the first molar site and the anterior implants placed in the regions from first premolar to lateral incisor. These six implants are cross-arch stabilized with a framework or bar. Either a hybrid-type prosthesis is fabricated and screw retained or a fixed-removable prosthesis is fabricated for patient removal and cleaning. Cantilevers are limited in the maxilla because of the soft nature of maxillary bone.

If a type of bar structure is planned, the implants should be placed within the confines of the borders of the planned prosthesis, not labial to or outside of the borders of the teeth. The implants should be placed to avoid impinging on the teeth in the overdenture and to allow space for fabrication of the bar. The surgical guide stent is made after a complete setup has been performed to allow for accurate planning of placement of the implants in the ideal position for bar fabrication. Careful attention to the position of the incisal edges of the lower teeth provides important information that can prevent conflicts of space between the lower teeth and the palatal portion of the overdenture and the underlying bar. For many of these implant-borne cases, implants are placed from the canine region and extend posteriorly, with a minimal number of implants placed into the incisal region. This pattern of placement makes the design of the anterior portion of the prosthesis easier. However, for patients with shorter vertical bone in the posterior maxilla (e.g., 10 mm), placement of longer implants in the anterior region may be indicated because of the need for mechanical strength for prosthesis loading during chewing.

Incisions for full-arch distribution of implants placed into the maxilla usually are placed slightly palatal or over the crest. Vertical release incisions are made posterior to the most distal implant, which typically is in the first or second molar region. Anterior, midline, vertical release incisions usually are not necessary. Midline releasing incisions cause increased postoperative discomfort. Planning for incision breakdown is recommended; thus, placing the incisions on the crest ensures that the KG will be labial to the implants. A vestibular incision or an incision made at the junction of the attached and unattached gingivae may result in loose gingiva adjacent to the implants if incision breakdown occurs (Figure 3-5).

For patients who desire a fixed crown and bridge restoration, a surgical guide stent must be available to identify the specific locations of the implants. This stent should have full palatal coverage and, if present, intimately adapt to the remaining dentition. For a patient whose treatment plan includes a fixed removable prosthesis (e.g., spark erosion, precision bar–retained overdenture), the implant position is more flexible. The implants should be placed slightly to the palatal aspect to allow sufficient room for the teeth to be placed without encroaching on the framework. However, if the implants are placed too far to the palatal aspect, the bar and denture will have excessive bulk palatally, which will impair speech and function and impinge on the natural tongue position. A surgical guide stent with a slot can guide the surgeon to the boundaries for implant location. Bone reduction may be necessary to provide 15 mm of adequate space for the prosthesis that has significant framework dimensions.

A local anesthetic is infiltrated into the labial and palatal regions of the maxilla. A crestal incision is made, moving labially around the incisive papilla to avoid transection of its contents. The incision is made through the periosteum to bone. A full-thickness mucoperiosteal flap is raised, with care taken to prevent trauma and avoid perforating the flap. A full-thickness palatal reflection is performed to identify the slope of the palatal cortex.

After the labial and palatal tissues have been reflected, the surgeon should have a view of the crestal bone thickness and the contours of the palatal and facial cortical bone. The bone width is confirmed, and the surgical stent is placed. The areas of planned implant placement are identified and marked with a round bur.

All implant sites should be prepared sequentially, using the pilot drill, with serial placement of the parallel or guide pins to help align the implants with each other. The exception is intentionally angling implants and the use of angled abutments.

The surgical guide stent should be used as much as possible to ensure correct positioning of the implants. In most cases with adequate bone, the implants are positioned to allow for draw as a unit. If the alveolar bone is angled because of protrusiveness, the implants may be angled. Angle correction abutments or custom abutments can be used to correct angulation issues easily. The abutments are paralleled to allow for screw retention, cement retention, and draw of the unit. Choice of implant system may be dependent on abutment needs.

As the drill diameters increase, careful attention is needed to prevent bone dehiscence. The surgeon may need to move an implant along the ridge mesially and distally or facially and palatally to engage the thickest bone possible. If performed with the aid of a surgical guide stent, these changes will not adversely affect the restoration. However, when implants are placed for a fixed crown and bridge restoration, which is screw retained or cemented, there is less tolerance for small changes. These implants must be placed exactly where prescribed and follow preoperative virtual planning. Overdenture and fixed-removable (e.g., spark erosion or precision milled bar) prostheses allow the surgeon more freedom of implant placement.

Before implant placement and after confirmation of primary implant stability, a decision to place cover screws, healing abutments, or prosthetic abutments into the implant bodies is made. Then the incisions are closed. Occasionally, the periosteum needs to be released to allow tension-free closure. If no graft has been placed, the type of suture depends on the clinician’s preference.

When immediate provisionalization is not chosen, patients are strongly encouraged to leave maxillary dentures out of the mouth for 7 to 10 days. If this is unacceptable to the patient, the denture is relieved and retained with denture adhesive on the palatal area. When patients have been appropriately counseled on the sequelae of trauma to the ridges and the potential loss of implants, they tend to cooperate. If an immediate provisional restoration is made, it is modified to avoid contact with the gingiva, relying on primary implant stability to retain the temporary prosthesis.

Grafting the thin maxilla

There are multiple reasons for patients to have thin, narrow alveolar bone, which does not allow implant placement. These ridges require augmentation before implant placement. Full arch augmentation often is required in patients who have periodontal bone loss with secondary dental protrusion. The teeth require removal during treatment. If a provisional fixed prosthesis is cement retained to the teeth and the augmentation is performed, there is a risk of incision breakdown because of the presence of the teeth. If an augmentation is performed and the incision breaks down, loss of graft material may result in compromised implant placement. It is recommended to remove teeth and augment the ridge to avoid incision breakdown. The patient may need to wear a denture for some period of the therapy to allow for the grafts to heal without loss of the graft volume. With good communication and education on the temporary nature of the removable prosthesis, patient cooperation has been good. The following case and discussion demonstrates such a situation.

Full arch rehabilitation in patients with systemic disease that adversely affects their teeth

Michael S. Block and Celeste Block

Patients with systemic lifelong systemic disease may present with dental compensations and problems that lead to severe bone loss, malposition of their teeth, and esthetic issues. The flaring of their teeth results in major functional and esthetic problems. They seek a functional, comfortable, and esthetic change.

Cyclic neutropenia is a rare hematologic disorder that is an inherited or acquired autosomal dominant disorder of the gene for protease neutrophil elastase (ELA-2 or ELANE). Neutrophil elastase normally synthesizes neutrophil precursors during primary granule formation.7 When a missense or deletion mutation occurs, apoptosis of neutrophil elastase precursors is accelerated and spontaneous, resulting in a reduced neutrophil production and the cyclic nature of this disorder.8 This apoptosis might be mediated by an abnormal proapoptotic factor called Bcl-2. 9,10 It is thought that mutated ELA-2 leads to impaired production and survival of bone marrow–derived myeloid-committed progenitor cells and an increased proliferation of primitive CD34+ progenitor cells.8,1113

Clinical characteristics in the child and young adult are recurrent fever and skin and throat inflammation including ulcers, gingivitis, respiratory infections, and sinusitis. Between neutropenic intervals, the patient is usually healthy.8,14,15

A normal absolute neutrophil count (ANC) is above 1500 cells per microliter (1.5 K/µL). An ANC less than 0.5 K/µL is defined as neutropenia and significantly increases the risk of infection. Neutropenia is the condition of a low ANC, and the most common condition in which an ANC would be measured is in the setting of chemotherapy for cancer.16

The cycles of cyclic neutropenia occur every 21 days and last for 3 to 5 days during which the circulating neutrophil count decreases to about 0.2 K/µLat the nadir of the cycle.10 As the neutrophil count decreases, the monocyte and eosinophil levels increase.11 When the neutrophil count is extremely low, life-threatening infections commonly occur. Cyclic neutropenia can occur at any age, but a large percentage occurs during childhood. Neutrophil levels continue to cycle, but symptoms decrease in severity after the second decade of life.11

This patient has evidence of chronic bone loss, which appears similar to chronic periodontal disease. What is the success of placing implants in patients with chronic periodontal disease?

Within the first 5 years of implant placement, both periodontal patients and nonperiodontal patients share similar results. After 5 years, more significant differences arise among periodontal patients such as greater marginal bone loss because of maintenance issues. Patients with a history of periodontitis must be kept on a strict hygiene recall as well as educated on proper oral hygiene to maintain healthy tissues needed for implant therapy.17,18 Smaller studies imply that there is a difference but not at a statistically significant level.1921 Treating periodontally compromised patients before and after implant placement helps the success of implant therapy, as reported in a 10-year follow-up study. Putting patients on a regular recall schedule contributed to more successful outcomes. This study showed greater bone loss around an implant in a periodontally compromised patient compared with a periodontally healthy patient.19

In a study of 10 patients with a history of periodontitis, immediate implant placement into an extraction site showed successful osseointegration. These authors believed that success was due to a decrease in treatment time and a flapless surgery. By doing a flapless surgery, the blood supply was not altered. They also used periodontal therapy to reduce the microbial load to prevent inflammation.22

The microbial flora present subgingivally before extractions and after implant placement was reduced for both aerobes and anaerobes. There was a slight increase in anaerobes present around the implant site. The specific flora around the implant that was reduced over time includes but is not limited to Tannerella forsythia and Prevotella intermedia. However, there was not a notable change in Aggregatibacter actinomycetemcomitans around the implant site.23

This 59-year-old woman presented with several complaints, including flaring of her teeth, mobility of her teeth, chronic dental pain, and the inability to chew a normally textured diet. She was also concerned about her facial appearance (Figure 3-6).

She was diagnosed with cyclic neutropenia at the age of 2 years. She had chronic lung, sinus, and gingival infections until she reached the age of 16 years. She started her menses at 14 years. She reported minimal severe problems with her lungs, urinary system, and skin after she reached 16 years of age. In the past 30 years, she has had chronic sinus problems and developed upper mild respiratory infections four or five times each year. Since she reached puberty, her white blood cell (WBC) count has been slightly lower than normal or low normal, ranging from 3.5 to 4.7 K/μL. Her absolute number of neutrophils (ANC) ranges from 0.4 to 0.9 K/μL. Her lymphocytes, monocytes, eosinophils, and basophils are all higher than normal, explaining her low normal total WBC counts. Her segmented neutrophils range from 8% to 21% of the normal 36% to 66% range of total WBCs.

Her neutrophil counts still cycle. Her teeth developed chronic bone loss, which progressed in the face of conservative periodontal therapy, including root planning without surgical intervention. At the age of 30 years, her mandibular teeth were splinted because of mobility. The flaring progressed slowly from her 20s and appeared to stabilize with splinting. She now desires treatment to correct her current situation.

A cone-beam scan (ICAT, Image Sciences International) was taken as well as diagnostic models.

Her facial examination showed:

Her problem list includes:

Treatment plan

Her treatment was phased after consultation with the patient’s internist and hematologist. They did not believe that she would be a surgical risk but were concerned about her response to control infection. Her current WBC was 4.3 L.

Phase 1

The initial treatment was to develop an ideal setup of her teeth. Diagnostic casts were mounted, and the maxillary teeth were set to correct her anterior flaring based on the following principles.

1. Because of the extreme proclination of the maxillary incisors, her current incisor position needed to be corrected. The buccal-lingual position of the central incisor was established based on the anatomical average distance from the distal border of the incisive papilla to the outer labial surface of maxillary incisor. The average reported distance is 12.5 mm with a standard deviation of 3.8 mm.24 In this case, the position of her current central incisor distance was 16 mm. The teeth on the immediate denture were set to bring the incisal edge position 4 mm lingual to her current position.

2. The vertical position of the central incisor was established based on the anatomical average distance measured from the base of the sulcus to the incisive edge of the maxillary incisor. The reported average vertical distance is 22 mm. This distance was used to provide a reference for the placement of the central incisor tooth vertical position.24

3. A practical method used to establish the buccal-lingual angulation of the maxillary central incisor was by recording the angle made between the central incisor’s incisal third and the maxillary posterior occlusal plane. When the angle is acute like in this patient, the incisal third is overcontoured or protruded and should be restored back to its normal 90-degree position. This was used as part of the setup to maintain an appropriate esthetic analysis.25

Phase 2: Surgical treatment 1

Under intravenous sedation, the patient’s mouth was anesthetized. The plan was to remove the maxillary and mandibular teeth, graft the sockets of the maxillary teeth as well as onlay graft the thin ridge in the maxilla, and reduce the alveolar bone in the mandible to sufficient width for later placement of implants.

Maxilla. 

​Sulcular incisions were made, and a full-thickness flap was elevated to expose the lateral aspect of the maxilla up to the piriform rim. The periosteum was scored and released to facilitate a tension-free closure. The teeth were removed with the aid of a piezosurgery periotome-like tip. Sharp edges of bone were conservatively smoothed. Human mineralized cortical bone, 350 to 500 microns, was placed into the extraction sockets. A long-lasting collagen membrane (Osseoguard, Biomet 3i) was placed under the mucosa flap. Bovine xenograft (Endobon, Biomet 3i, Palm Beach Gardens, FL) was onlayed over the thin labial bone and under the collagen membrane. The ridge width augmentation was approximately 4 mm. The crestal gingiva was closed in a running suture using 4-0 chromic sutures. Interrupted 4-0 chromic sutures were placed in crestal sites to aid on flap retention. The immediate denture was placed and fit nicely with no need for soft lining.

Computed tomography–guided surgery in the edentulous maxilla

Several reasons support the use of CT-guided surgery for the placement of implants in the edentulous maxilla.

1. Implants can be placed in the ideal position based on preoperative planning. The implants are placed on the computer to the ideal locations as determined by fabrication of a radiographic duplicate of the planned restoration. The initial procedure performed by the restorative dentist determines the exact location of the teeth. This often requires fabrication of a new denture. The new denture, with its approved form, function, and esthetics, is duplicated for scanning. The duplicated denture is used to direct implant placement, with the type of final prosthesis taken into consideration. For example, if the final prosthesis is to be a fixed crown and bridge, the implants must be placed so as to avoid embrasures and 3 mm apical to the planned gingival margin position on the final prosthesis. If the final prosthesis is to be the fixed-removable type with a bar, the implants must be placed with sufficient space for fabrication of the bar and prosthesis, which includes a metallic intaglio surface that interdigitates with the milled bar. If the planned prosthesis is a hybrid denture, the implants must be placed with consideration given to the space necessary for cleaning the fixed prosthesis, which can be removed by the dentist but not by the patient.

With the advent of angled abutments, implants can be planned for placement bisecting the cortical plates of available bone, optimizing implant length. The angles created can be predicted. The angle correction of the abutments which include 17- and 30-degree options for most implant systems, can be predicted and ordered, avoiding excessive parts that need to be available at the time of surgery. The efficiency of the orchestration of the surgery and restorative portion is enhanced by preoperative preparation.

In a patient who has had lateral ridge augmentation using particulate graft material, flap elevation can add the risk of dislodgement of the graft or raising the peripheral 1 to 3 mm of the onlayed graft when the flap is elevated. The bone ingrowth into a graft material may be along the inner 1 to 3 mm of the graft with fibrous tissue within the peripheral portio/>

Jan 5, 2015 | Posted by in Implantology | Comments Off on 3: Implants for the maxillary edentulous patient
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