Platelet-rich plasma: Growth factor enhancement for bone grafts

Platelet-rich plasma is an autologous source of platelet-derived growth factor and transforming growth factor beta that is obtained by sequestering and concentrating platelets by gradient density centrifugation. This technique produced a concentration of human platelets of 338% and identified platelet-derived growth factor and transforming growth factor beta within them. Monoclonal antibody assessment of cancellous cellular marrow grafts demonstrated cells that were capable of responding to the growth factors by bearing cell membrane receptors. The additional amounts of these growth factors obtained by adding platelet-rich plasma to grafts evidenced a radiographic maturation rate 1.62 to 2.16 times that of grafts without platelet-rich plasma. As assessed by histomorphometry, there was also a greater bone density in grafts in which platelet-rich plasma was added (74.0% +/- 11%) than in grafts in which platelet-rich plasma was not added (55.1% +/- 8%; p = 0.005).

Enhanced bone apposition to a chemically modified SLA titanium surface

Increased surface roughness of dental implants has demonstrated greater bone apposition; however, the effect of modifying surface chemistry remains unknown. In the present study, we evaluated bone apposition to a modified sandblasted/acid-etched (modSLA) titanium surface, as compared with a standard SLA surface, during early stages of bone regeneration. Experimental implants were placed in miniature pigs, creating 2 circular bone defects. Test and control implants had the same topography, but differed in surface chemistry. We created the test surface by submerging the implant in an isotonic NaCl solution following acid-etching to avoid contamination with molecules from the atmosphere. Test implants demonstrated a significantly greater mean percentage of bone-implant contact as compared with controls at 2 (49.30 vs. 29.42%; p = 0.017) and 4 wks (81.91 vs. 66.57%; p = 0.011) of healing. At 8 wks, similar results were observed. It is concluded that the modSLA surface promoted enhanced bone apposition during early stages of bone regeneration.

Biological factors contributing to failures of osseointegrated oral implants. (I). Success criteria and epidemiology

The aim of this review was to offer a critical evaluation of the literature and to provide the clinician with scientifically-based diagnostic criteria for monitoring the implant condition. The review presents the current opinions on definitions of osseointegration and implant failure. Further, distinctions between failed and failing implants are discussed together with the presently used parameters to assess the implant status. Radiographic examinations together with implant mobility tests seem to be the most reliable parameters in the assessment of the prognosis for osseointegrated implants. On the basis of 73 published articles, the rates of early and late failures of Brånemark implants, used in various anatomical locations and clinical situations, were analyzed using a metanalytic approach. Biologically related implant failures calculated on a sample of 2,812 implants were relatively rare: 7.7% over a 5-year period (bone graft excluded). The predictability of implant treatment was remarkable, particularly for partially edentulous patients, who showed failure rates about half those of totally edentulous subjects. Our analysis also confirmed (for both early and late failures) the general trend of maxillas, having almost 3 times more implant losses than mandibles, with the exception of the partially edentulous situation which displayed similar failure rates both in upper and lower jaws. Surgical trauma together with anatomical conditions are believed to be the most important etiological factors for early implant losses (3.60% of 16,935 implants). The low prevalence of failures attributable to peri-implantitis found in the literature together with the fact that, in general, partially edentulous patients have less resorbed jaws, speak in favour of jaw volume, bone quality, and overload as the three major determinants for late implant failures in the Brånemark system. Conversely, the ITI system seemed to be characterized by a higher prevalence of losses due to peri-implantitis. These differences may be attributed to the different implant designs and surface characteristics. On the basis of the published literature, there appears to be a number of scientific issues which are yet not fully understood. Therefore, it is concluded that further clinical follow-up and retrieval studies are required in order to achieve a better understanding of the mechanisms for failure of osseointegrated implants.

The osteocutaneous scapular flap for mandibular and maxillary reconstruction

Microfil injections in 8 cadavers and clinical experience with 26 patients have demonstrated a reliable blood supply to the lateral border of the scapula based on branches of the circumflex scapular artery. This tissue has been used successfully for reconstruction of a variety of defects resulting from maxillectomy and mandibular defects from cancer and benign tumor excisions. Advantages of this tissue over previous reconstructive methods include the ability to design multiple cutaneous panels on a separate vascular pedicle from the bone flap allowing improvement in three-dimensional spatial relationships for complex mandibular and maxillary reconstructions. The lateral border of the scapula provides up to 14 cm of thick, straight corticocancellous bone that can be osteotomized where desired. The thin blade of the scapula provides optimum tissues for palate and orbital floor reconstruction. There have been no flap failures and minimal donor-site complications.

Nine- to fourteen-year follow-up of implant treatment. Part II: presence of peri-implant lesions

OBJECTIVES

The aim of this study was to analyse the proportions of peri-implant lesions at implants after 9-14 years of function.

MATERIAL AND METHODS

Two hundred and ninety-four patients underwent implant therapy during the years 1988-1992 in Kristianstad County. These individuals were recalled to the speciality clinic 1 and 5 years after placement of the suprastructure. Between 2000 and 2002, 218 patients with 999 implants were examined clinically and radiographically.

RESULTS

Forty-eight per cent of the implants had probing depth > or =4 mm and bleeding on probing (peri-implant mucositis). In 20.4% of the implants, the bone level was located 3.1 mm apical to the implant shoulder. Progressive bone loss (> or =1.8 mm) during the observation period was found in 7.7% of the implants. Peri-implantitis defined as bone loss > or =1.8 mm compared with 1-year data (the apical border of the bony defect located at or apical to the third thread, i.e. a minimum of 3.1 mm apical to the implant shoulder), combined with bleeding on probing and or pus, were diagnosed among 16% of the patients and 6.6% of the implants.

CONCLUSION

After 10 years in use without systematic supportive treatment, peri-implant lesions is a common clinical entity adjacent to titanium implants.

Ridge preservation with freeze-dried bone allograft and a collagen membrane compared to extraction alone for implant site development: a clinical and histologic study in humans

BACKGROUND

Tooth extraction typically leads to loss of ridge width and height. The primary aim of this 6-month randomized, controlled, blinded, clinical study was to determine whether ridge preservation would prevent post-extraction resorptive changes as assessed by clinical and histologic parameters.

METHODS

Twenty-four patients, 10 males and 14 females, aged 28 to 76 (mean 51.5 +/- 13.6), requiring a non-molar extraction and delayed implant placement were randomly selected to receive either extraction alone (EXT) or ridge preservation (RP) using tetracycline hydrated freeze-dried bone allograft (FDBA) and a collagen membrane. A replaced flap, which did not completely cover the sockets, was used. Following extraction, horizontal and vertical ridge dimensions were determined using a modified digital caliper and an acrylic stent, respectively. Prior to implant placement, a 2.7 x 6.0 mm trephine core was obtained and preserved in formalin for histologic analysis.

RESULTS

The width of the RP group decreased from 9.2 +/- 1.2 mm to 8.0 +/- 1.4 mm (P<0.05), while the width of the EXT group decreased from 9.1 +/- 1.0 mm to 6.4 +/- 2.2 mm (P<0.05), a difference of 1.6 mm. Both the EXT and RP groups lost ridge width, although an improved result was obtained in the RP group. Most of the resorption occurred from the buccal; maxillary sites lost more width than mandibular sites. The vertical change for the RP group was a gain of 1.3 +/- 2.0 mm versus a loss of 0.9 +/- 1.6 mm for the EXT group (P<0.05), a height difference of 2.2 mm. Histologic analysis revealed more bone in the RP group: about 65 +/- 10% versus 54 +/- 12% in the EXT group. The RP group included both vital bone (28%) and non-vital (37%) FDBA fragments.

CONCLUSIONS

Ridge preservation using FDBA and a collagen membrane improved ridge height and width dimensions when compared to extraction alone. These dimensions may be more suitable for implant placement, especially in areas where loss of ridge height would compromise the esthetic result. The quantity of bone observed on histologic analysis was slightly greater in preservation sites, although these sites included both vital and non-vital bone. The most predictable maintenance of ridge width, height, and position was achieved when a ridge preservation procedure was employed.

Management of severe maxillary deficiency in childhood and adolescence through distraction osteogenesis with an external, adjustable, rigid distraction device

We present our technique for maxillary distraction osteogenesis in patients with severe maxillary hypoplasia. With the use of an external, adjustable, rigid distraction device, we can now treat patients with severe maxillary hypoplasia with a precise and controlled distraction process, obtaining predictable results. This technique has allowed us to treat patients in all age groups. In this report we review our indications for maxillary distraction and describe our technique using an external, adjustable, rigid midface distraction device.

Obstructive sleep apnea syndrome: a review of 306 consecutively treated surgical patients

Three hundred six consecutively treated surgical patients with obstructive sleep apnea syndrome were evaluated from a group of 415 patients. One hundred nine patients were excluded because they failed to obtain a postoperative polysomnogram or were lost to followup. All patients received a physical examination, cephalometric analysis, fiberoptic examination, and polysomnography before treatment to document OSAS and determine the areas of obstruction. A two-phase surgical protocol was used for the reconstruction of the upper airway. Phase I surgery consisted of a uvulopalatopharyngoplasty (UPPP) for palatal obstruction and genioglossus advancement with hyoid myotomy-suspension for base of tongue obstruction. Failures of phase I were offered phase 2 reconstruction, which consisted of maxillary-mandibular advancement osteotomy. One hundred twenty-one patients were treated with nasal continuous positive airway pressure (CPAP) before surgery and this was the primary method of evaluating surgical success. Results were reported on the polysomnogram performed a minimum of 6 months after surgery and compared to the preoperative polysomnogram and the second night nasal CPAP study. The polysomnographic results included respiratory disturbance index (RDI), lowest oxyhemoglobin saturation (LSAT), and sleep architecture parameters. Surgery was considered a success if it was equivalent to nasal CPAP or the postoperative RDI was less than 20 with normal oxygenation. The overall success rate, which included patients that dropped from the protocol, was 76.5%, with a mean followup of 9.3 months (SD, 6.7). The preoperative RDI, nasal CPAP RDI, and postoperative RDI were 55.8 (SD, 26.7), 7.2 (SD, 5.4), and 9.2 (SD, 7.5), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of bone thickness on facial marginal bone response: stage 1 placement through stage 2 uncovering

BACKGROUND

Various causes of facial bone loss around dental implants are reported in the literature; however, reports on the influence of residual facial bone thickness on the facial bone response (loss or gain) have not been published. This study measured changes in vertical dimension of facial bone between implant insertion and uncovering and compared these changes to facial bone thickness for more than 3,000 hydroxyapatite (HA)-coated and non-HA-coated root-form dental implants.

METHODS

Subjects were predominantly white males, 18 to 80+ years of age (mean 62.9 years), who were patients at 30 Department of Veterans Affairs Medical Centers and two university dental clinics. Alveolar ridges ranged from normal to resorbed with intact basal bone. Following preparation of the osteotomy site, direct measurements with calipers were made of the residual facial bone thickness, approximately 0.5 mm below the crest of the bone. The distance from the top of the implants to the crest of the facial bone was also measured using periodontal probes. Implants were uncovered between 3 to 4 months in the mandible and 6 to 8 months in the maxilla after insertion. Facial bone response was the difference between the height of facial bone at Stage 1 (insertion) and Stage 2 (uncovering).

RESULTS

The mean facial bone thickness after osteotomies were made was 1.7 +/- 1.13 mm. When a mean facial bone thickness of 1.8 +/- 1.41 mm or larger remained after site preparation, bone apposition was more likely to occur. The mean facial bone response for 2,685 implants was -0.7 +/- 1.70 mm. For implants integrated at uncovering, the mean bone response was -0.7 +/- 1.69 mm, and -2.8 +/- 1.57 mm for implants mobile at uncovering. Bone quality-4 had the least facial bone response, -0.5 +/- 2.11 mm. Bone responses were similar for both HA-coated and non-HA-coated implants.

CONCLUSIONS

Significantly greater amounts of facial bone loss were associated with implants that failed to integrate. As the bone thickness approached 1.8 to 2 mm, bone loss decreased significantly and some evidence of bone gain was seen. There was no statistically or clinically significant difference in bone response between HA-coated and non-HA-coated implants.

Esthetic outcomes following immediate and early implant placement in the anterior maxilla--a systematic review

PURPOSE

The objectives of this systematic review are (1) to quantitatively estimate the esthetic outcomes of implants placed in postextraction sites, and (2) to evaluate the influence of simultaneous bone augmentation procedures on these outcomes.

MATERIALS AND METHODS

Electronic and manual searches of the dental literature were performed to collect information on esthetic outcomes based on objective criteria with implants placed after extraction of maxillary anterior and premolar teeth. All levels of evidence were accepted (case series studies required a minimum of 5 cases).

RESULTS

From 1,686 titles, 114 full-text articles were evaluated and 50 records included for data extraction. The included studies reported on single-tooth implants adjacent to natural teeth, with no studies on multiple missing teeth identified (6 randomized controlled trials, 6 cohort studies, 5 cross-sectional studies, and 33 case series studies). Considerable heterogeneity in study design was found. A meta-analysis of controlled studies was not possible. The available evidence suggests that esthetic outcomes, determined by esthetic indices (predominantly the pink esthetic score) and positional changes of the peri-implant mucosa, may be achieved for single-tooth implants placed after tooth extraction. Immediate (type 1) implant placement, however, is associated with a greater variability in outcomes and a higher frequency of recession of > 1 mm of the midfacial mucosa (eight studies; range 9% to 41% and median 26% of sites, 1 to 3 years after placement) compared to early (type 2 and type 3) implant placement (2 studies; no sites with recession > 1 mm). In two retrospective studies of immediate (type 1) implant placement with bone graft, the facial bone wall was not detectable on cone beam CT in 36% and 57% of sites. These sites had more recession of the midfacial mucosa compared to sites with detectable facial bone. Two studies of early implant placement (types 2 and 3) combined with simultaneous bone augmentation with GBR (contour augmentation) demonstrated a high frequency (above 90%) of facial bone wall visible on CBCT. Recent studies of immediate (type 1) placement imposed specific selection criteria, including thick tissue biotype and an intact facial socket wall, to reduce esthetic risk. There were no specific selection criteria for early (type 2 and type 3) implant placement.

CONCLUSIONS

Acceptable esthetic outcomes may be achieved with implants placed after extraction of teeth in the maxillary anterior and premolar areas of the dentition. Recession of the midfacial mucosa is a risk with immediate (type 1) placement. Further research is needed to investigate the most suitable biomaterials to reconstruct the facial bone and the relationship between long-term mucosal stability and presence/absence of the facial bone, the thickness of the facial bone, and the position of the facial bone crest.

The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension

A hierarchy of stability exists among the types of surgical movements that are possible with orthognathic surgery. This report updates the hierarchy, focusing on comparison of the stability of procedures when rigid fixation is used. Two procedures not previously placed in the hierarchy now are included: correction of asymmetry is stable with rigid fixation and repositioning of the chin also is very stable. During the first post-surgical year, surgical movements in patients treated for Class II/long face problems tend to be more stable than those treated for Class III problems. Clinically relevant changes (more than 2 mm) occur in a surprisingly large percentage of orthognathic surgery patients from one to five years post-treatment, after surgical healing is complete. During the first post-surgical year, patients treated for Class II/long face problems are more stable than those treated for Class III problems; from one to five years post-treatment, some patients in both groups experience skeletal change, but the Class III patients then are more stable than the Class II/long face patients. Fewer patients exhibit long-term changes in the dental occlusion than skeletal changes, because the dentition usually adapts to the skeletal change.

Incidence of complications and problems related to orthognathic surgery: a review of 655 patients

PURPOSE

This retrospective report evaluates the incidence of pre-, intra-, and postoperative complications of orthognathic surgery and their significance to the patient.

PATIENTS AND METHODS

The clinical records and radiographs of 655 patients operated on in Vaasa Central Hospital, Finland during a 13-year period between 1983 and 1996 were examined. The total number of operations was 689. All notes referring to problems or complications from the orthodontic phase to the varying postoperative follow-up times were gathered and analyzed.

RESULTS

The most common complication was a neurosensory deficit in the region innervated by the inferior alveolar nerve; mild in 32% of patients (183 of 574 patients with an osteotomy in the mandible) and disturbing in 3% of patients (18/574). The most serious complication was severe intraoperative bleeding in 1 patient necessitating major blood transfusions and later embolization of the internal maxillary artery. There were no fatal complications. The incidence of other problems was low, and there were very few patient complaints.

CONCLUSIONS

Despite the great variety of severe complications reported in the literature, their frequency seems to be extremely low, and orthognathic surgery treatment can be considered to be a safe procedure.

Clinical and radiographic evaluation of the papilla level adjacent to single-tooth dental implants. A retrospective study in the maxillary anterior region

BACKGROUND

The regeneration of gingival papillae after single-implant treatment is an area of current investigation. This study was designed to determine: 1) whether the distance from the base of the contact point to the crest of the bone would correlate with the presence or absence of interproximal papillae adjacent to single-tooth implants, and 2) whether the surgical technique at uncovering influences the outcome.

METHODS

A clinical and radiographic retrospective evaluation of the papilla level around single dental implants and their adjacent teeth was performed in the anterior maxilla in 26 patients restored with 27 implants. Six months after insertion, 17 implants were uncovered with a standard technique, while 10 implants were uncovered with a technique designed to generate papilla-like formation around dental implants. Fifty-two papillae were available for clinical and radiographic evaluation. The presence or absence of papillae was determined, and the effects of the following variables were analyzed: the influence of the 2 surgical techniques; the vertical relation between the papilla height and the crest of bone between the implant and adjacent teeth; the vertical relation between the papilla level and the contact point between the crowns of the teeth and the implant; and the distance from the contact point to the crest of bone.

RESULTS

When the measurement from the contact point to the crest of bone was 5 mm or less, the papilla was present almost 100% of the time. When the distance was > or = 6 mm, the papilla was present 50% of the time or less. The mean distance between the crest of bone and the most coronal papilla level (interproximal soft tissue height) was 3.85 mm (SD = 1.04). When comparing the conventional and modified surgical technique, the relation shifted from 3.77 mm (SD = 1.01) to 4.01 mm (SD = 1.10), respectively.

CONCLUSIONS

These results clearly show the influence of the bone crest on the presence or absence of papillae between implants and adjacent teeth. The data also show a positive influence for the modified surgical technique, aimed at reconstructing papillae at the implant uncovering.

A classification system and algorithm for reconstruction of maxillectomy and midfacial defects

Maxillectomy defects become more complex when critical structures such as the orbit, globe, and cranial base are resected, and reconstruction with distant tissues becomes essential. This study reviews all maxillectomy defects reconstructed immediately using pedicled and free flaps to establish (1) a classification system and (2) an algorithm for reconstruction of these complex problems. Over a 5-year period, 60 flaps were used to reconstruct defects classified as the following: type I, limited maxillectomy (n = 7); type II, subtotal maxillectomy (n = 10); type IIIa, total maxillectomy with preservation of the orbital contents (n = 13); type IIIb, total maxillectomy with orbital exenteration (n = 18); and type IV, orbitomaxillectomy (n = 10). Free flaps (45 rectus abdominis and 10 radial forearm) were used in 55 patients (91.7 percent), and the temporalis muscle was transposed in five elderly patients who were not free-flap candidates. Vascularized (radial forearm osteocutaneous) bone flaps were used in four of the 60 patients (6.7 percent) and nonvascularized bone grafts in 17 (28.3 percent). Simultaneous reconstruction of the oral commissure using an Estandler procedure was performed in 10 patients with maxillectomy and through-and-through soft-tissue defects. Free-flap survival was 100 percent, with reexploration in five of 55 patients (9.1 percent) and partial-flap necrosis in one patient. Seven of the 60 patients (11.7 percent) had systemic complications, and four died within 30 days of hospitalization. Fifty patients had more than 6 months of follow-up with a mean time of 27.7 (+/- 15.6) months. Postoperative radiotherapy was administered in 32 of these patients (64.0 percent). Chewing and speech functions were assessed in 36 patients with type II, IIIa, and IIIb defects. A prosthetic denture was fixed in 15 of 36 patients (41.7 percent). Return to an unrestricted diet was seen in 16 patients (44.4 percent), a soft diet in 17 (47.2 percent), and a liquid diet in three (8.3 percent). Speech was assessed as normal in 14 of 36 patients (38.9 percent), near normal in 15 (41.7 percent), intelligible in six (16.7 percent), and unintelligible in one patient (2.8 percent). Globe and periorbital soft-tissue position was assessed in 14 patients with type I and IIIa defects. There were no cases of enophthalmos, and one patient had a mild vertical dystopia. Ectropion was observed in 10 of 14 patients (71.4 percent). Oral competence was considered good in all 10 patients with excision/reconstruction of the oral commissure; however, two patients (20 percent) developed microstomia after receiving radiotherapy. Aesthetic results were evaluated at least 6 months after reconstruction in 50 patients. They were good to excellent in 29 patients (58 percent) for whom cheek skin and lip were not resected, and poor to fair (42 percent) when the external skin or orbital contents were excised. Secondary procedures were required in 16 of 50 patients (32.0 percent). Free-tissue transfer provides the most effective and reliable form of immediate reconstruction for complex maxillectomy defects. The rectus abdominis and radial forearm flaps in combination with immediate bone grafting or as osteocutaneous flaps reliably provide the best aesthetic and functional results. An algorithm based on the type of maxillary resection can be followed to determine the best approach to reconstruction.

Clinical results of alveolar ridge augmentation with mandibular block bone grafts in partially edentulous patients prior to implant placement

A group of 15 partially edentulous patients who needed alveolar ridge augmentation for implant placement, were consecutively treated using a two-stage technique in an outpatient environment. A total of 18 alveolar segments were grafted. During the first operation bone blocks harvested from the mandibular ramus or symphysis were placed as lateral or vertical onlay grafts and fixed with titanium osteosynthesis screws after exposure of the deficient alveolar ridge. After 6 months of healing the flap was re-opened, the screws were removed and the implants placed. Twelve months after the first operation implant-supported fixed bridges could be provided to the patients. Mean lateral augmentation obtained at the time of bone grafting was 6.5 +/- 0.33 mm, that reduced during healing because of graft resorption to a mean of 5.0 +/- 0.23 mm. Mean vertical augmentation obtained in the 9 sites where it was needed was 3.4 +/- 0.66 mm at bone grafting and 2.2 +/- 0.66 mm at implant placement. Mean lateral and vertical augmentation decreased by 23.5% and 42%, respectively, during bone graft healing (before implant insertion). Mandibular sites showed a larger amount of bone graft resorption than maxillary sites. All the 40 implants placed were integrated at the abutment connection and after prosthetic loading (mean follow-up was 12 months). No major complications were recorded at donor or recipient sites. Soft tissue healing was uneventful, and pain and swelling were comparable to usual dentoalveolar procedures. A visible ecchymosis was present for 4 to 7 days when the bone was harvested from the mandibular symphysis. From a clinical point of view this procedure appears to be simple, safe and effective for treating localised alveolar ridge defects in partially edentulous patients.

Ramus or chin grafts for maxillary sinus inlay and local onlay augmentation: comparison of donor site morbidity and complications

BACKGROUND

The placement of endosseous implants in edentulous areas is frequently limited by inadequate bone volume of the residual ridge. Local bone grafts from the mandible are a convenient source of autogenous bone for alveolar reconstruction prior to implant placement.

PURPOSE

The aim of the present study was to document and compare the morbidity and the frequency of complications occurring at two intraoral donor sites: the mandibular symphysis and the mandibular ramus.

MATERIAL AND METHODS

This study reviewed 53 consecutively treated patients: 29 with autogenous bone grafts from the mandibular symphysis and 24 with mandibular ramus bone grafts. Each patient received a questionnaire 18 months after surgery regarding problems that may have occurred during the postoperative period.

RESULTS

In the patients in whom bone was harvested from the mandibular ramus, there were fewer postoperative symptoms immediately after the operation than with mandibular symphysis harvesting. Twenty-two of the 29 patients with symphysis grafts experienced decreased sensitivity in the skin innervated by the mental nerve 1 month after the operation. Five of the 24 patients with ramus grafts experienced decreased sensitivity in the vestibular mucosa corresponding to the innervation of the buccal nerve. Eighteen months after the surgery, 15 of the 29 patients in the symphysis group still had some decreased sensitivity and presented with permanent altered sensation. Only one of the patients grafted from the mandibular ramus presented with permanent altered sensation in the posterior vestibular area. No major complication occurred in the donor sites in any of the 53 patients.

CONCLUSION

The results of this study favored the use of the ascending mandibular ramus as an intraoral donor site for bone grafting.

All-on-4 Immediate-Function Concept with Branemark SystemR Implants for Completely Edentulous Maxillae: A 1-Year Retrospective Clinical Study

BACKGROUND

Immediate implant function has become an accepted treatment modality for fixed restorations in totally edentulous mandibles, whereas experience from immediate function in the edentulous maxilla is limited.

PURPOSE

The purpose of this study was to evaluate a protocol for immediate function (within 3 hours) of four implants (All-on-4, Nobel Biocare AB, Göteborg, Sweden) supporting a fixed prosthesis in the completely edentulous maxilla.

MATERIALS AND METHODS

This retrospective clinical study included 32 patients with 128 immediately loaded implants (Brånemark System TiUnite, Nobel Biocare AB) supporting fixed complete-arch maxillary all-acrylic prostheses. A specially designed surgical guide was used to facilitate implant positioning and tilting of the posterior implants to achieve good bone anchorage and large interimplant distance for good prosthetic support. Follow-up examinations were performed at 6 and 12 months. Radiographic assessment of the marginal bone level was performed after 1 year in function.

RESULTS

Three immediately loaded implants were lost in three patients, giving a 1-year cumulative survival rate of 97.6%. The marginal bone level was, on average, 0.9 mm (SD 1.0 mm) from the implant/abutment junction after 1 year.

CONCLUSION

The high cumulative implant survival rate indicates that the immediate function concept for completely edentulous maxillae may be a viable concept.

Superimposition of 3D cone-beam CT models of orthognathic surgery patients

OBJECTIVES

To evaluate the registration of 3D models from cone-beam CT (CBCT) images taken before and after orthognathic surgery for the assessment of mandibular anatomy and position.

METHODS

CBCT scans were taken before and after orthognathic surgery for ten patients with various malocclusions undergoing maxillary surgery only. 3D models were constructed from the CBCT images utilizing semi-automatic segmentation and manual editing. The cranial base was used to register 3D models of pre- and post-surgery scans (1 week). After registration, a novel tool allowed the visual and quantitative assessment of post-operative changes via 2D overlays of superimposed models and 3D coloured displacement maps.

RESULTS

3D changes in mandibular rami position after surgical procedures were clearly illustrated by the 3D colour-coded maps. The average displacement of all surfaces was 0.77 mm (SD=0.17 mm), at the posterior border 0.78 mm (SD=0.25 mm), and at the condyle 0.70 mm (SD=0.07 mm). These displacements were close to the image spatial resolution of 0.60 mm. The average interobserver differences were negligible. The range of the interobserver errors for the average of all mandibular rami surface distances was 0.02 mm (SD=0.01 mm).

CONCLUSION

Our results suggest this method provides a valid and reproducible assessment of craniofacial structures for patients undergoing orthognathic surgery. This technique may be used to identify different patterns of ramus and condylar remodelling following orthognathic surgery.

A modified classification for the maxillectomy defect

BACKGROUND

At present no widely accepted classification exists for the maxillectomy defect suitable for surgeons and prosthodontists. An acceptable classification that describes the defect and indicates the likely functional and aesthetic outcome is needed.

METHODS

The classification is made on the basis of the assessment of 45 consecutive maxillectomy patients derived prospectively from the database (September 1992) and retrospectively from 1989.

RESULTS

The classification of the vertical component is as follows: Class 1, maxillectomy without an oro-antral fistula; Class 2, low maxillectomy (not including orbital floor or contents); Class 3, high maxillectomy (involving orbital contents); and Class 4, radical maxillectomy (includes orbital exenteration); Classes 2 to 4 are qualified by adding the letter a, b, or c. The horizontal or palatal component is classified as follows: a, unilateral alveolar maxillectomy; b, bilateral alveolar maxillectomy; and c, total alveolar maxillary resection.

CONCLUSION

This practical classification attempts to relate the likely aesthetic and functional outcomes of a maxillectomy to the method of rehabilitation.

Nine- to fourteen-year follow-up of implant treatment. Part I: implant loss and associations to various factors

OBJECTIVES

The aim of the present study was to evaluate the long-term result of implant therapy, using implant loss as outcome variable.

MATERIAL AND METHOD

Two hundred and ninty-four patients had received implant therapy (Brånemark System) during the years of 1988-1992 in Kristianstad County, Sweden. The patients were recalled to the speciality clinic 1 and 5 years after placement of the suprastructure. Between 2000 and 2002, 9-14 years after implant placements, the patients were again called in for a complete clinical and radiographic examination.

RESULTS

Two hundred and eighteen patients treated with 1057 implants were examined. Twenty-two patients had lost 46 implants and 12 implants were considered "sleeping implants". The overall survival rate was 95.7%. Implant loss appeared in a cluster in a few patients and early failures were most common. Eight patients lost more than one fixture. A significant relationship was observed between implant loss and periodontal bone loss of the remaining teeth at implant placement. Maxillary, as opposed to mandibulary implants, showed more implant loss if many implants were placed in the jaw. A significant relationship between smoking habits and implant loss was not found.

CONCLUSION

A history of periodontitis seems to be related to implant loss.

Prosthodontic guidelines for surgical reconstruction of the maxilla: a classification system of defects

Surgical reconstruction of maxillectomy defects has been described as an alternative to prosthetic rehabilitation to close the oral cavity. Advancements in microvascular surgical techniques require comprehensive treatment planning guidelines for functional rehabilitation. This retrospective study evaluated acquired maxillectomy defects after surgical reconstruction and/or prosthodontic rehabilitation in an attempt to establish surgical and prosthodontic guidelines that could be organized into a classification system. Forty-seven consecutive patient treatments of palatomaxillary reconstruction at a single facility, The Mount Sinai Medical Center (New York, N.Y.), were reviewed. All patients were rehabilitated with a tissue-borne obturator, a local advancement flap, a fasciocutaneous free flap, or a vascularized bone-containing free flap. Palatomaxillary defects were divided into 3 major classes and 2 subclasses. The aim of this defect-oriented classification system was to organize and define the complex nature of the restorative decision-making process for the maxillectomy patient.

Surgically assisted rapid palatal expansion: a literature review

Transverse maxillomandibular discrepancies are a major component of several malocclusions. Orthopedic and orthodontic forces are used routinely to correct a maxillary transverse deficiency (MTD) in a young patient. Correction of MTD in a skeletally mature patient is more challenging because of changes in the osseous articulations of the maxilla with the adjoining bones. Surgically assisted rapid palatal expansion (SARPE) has gradually gained popularity as a treatment option to correct MTD. It allows clinicians to achieve effective maxillary expansion in a skeletally mature patient. The use of SARPE to treat MTD decreases unwanted effects of orthopedic or orthodontic expansion. Our aim in this article is to present a comprehensive review of the literature, including indications, diagnosis, guidelines for case selection, a brief overview of the surgical techniques, orthodontic considerations, complications, risks, and limitations of SARPE to better aid the clinician in the management of MTD in skeletally mature patients.