Hendrikus Meijer

Implantology and the Severely Resorbed Edentulous Mandible

Patients with a severely resorbed edentulous mandible often suffer from problems with the lower denture. These problems include: insufficient retention of the lower denture, intolerance to loading by the mucosa, pain, difficulties with eating and speech, loss of soft-tissue support, and altered facial appearance. These problems are a challenge for the prosthodontist and surgeon. Dental implants have been shown to provide a reliable basis for fixed and removable prostheses. This has resulted in a drastic change in the treatment concepts for management of the severely resorbed edentulous mandible. Reconstructive, pre-prosthetic surgery has changed from surgery aimed to provide a sufficient osseous and mucosal support for a conventional denture into surgery aimed to provide a sufficient bone volume enabling implants to be placed at the most optimal positions from a prosthetic point of view. The aim of this paper is to review critically the literature on procedures related to the severely resorbed edentulous mandible and dental implant treatment. The study includes the transmandibular implant, (short) endosseous implants, and reconstructive procedures such as distraction osteogenesis, augmentation of the mandibular ridge with autogenous bone, and bone substitutes followed by the placement of implants. The number of patients participating in a study, the follow-up period, the design of the study, the degree of mandibular resorption, and the survival rate of the dental implants all are considered evaluation parameters. Although numerous studies have described the outcome results of dental implants in the edentulous mandible, there have been few prospective studies designed as randomized clinical trials that compare different treatment modalities to restore the severely resorbed mandible. Therefore, it is not yet possible to select an evidence-based treatment modality. Future research has to be focused on long-term, detailed follow-up clinical trials before scientifically based decisions in treating these patients can be made. This will contribute to a higher level of care in this field.

Maxillary sinus lift with solely autogenous bone compared to a combination of autogenous bone and growth factors or (solely) bone substitutes. A systematic review

Literature regarding the outcome of maxillary sinus floor elevation to create sufficient bone fraction to enable implant placement was systematically reviewed. Bone fraction and implant survival rate were assessed to determine whether grafting material or applied growth factor affected bone fraction. Trials where sinus floor elevations with autogenous bone (controls) were compared with autogenous bone combined with growth factors or bone substitutes, or solely with bone substitutes (test groups) were identified; 12 of 1124 fulfilled all inclusion criteria. Meta-analyses comparing the bone fraction after applying: autogenous bone; autologous bone with growth factors (platelet rich plasma); or autogenous bone and bone substitutes (bovine hydroxyapatite, bioactive glass, corticocancellous pig bone) revealed no significant differences in bone formation after 5 months. A significantly higher bone fraction was found in the autogenous bone group compared to the sole use of β-tricalciumphosphate (P=0.036). The one-year overall implant survival rate showed no significant difference between implants. Bone substitutes combined with autogenous bone provide a reliable alternative for autogenous bone as sole grafting material to reconstruct maxillary sinus bony deficiencies, for supporting dental implants after 5 months. Adding growth factors (platelet rich plasma) to grafting material and the sole use of β-tricalciumphosphate did not promote bone formation.

Reconstruction of the extremely resorbed mandible with interposed bone grafts and placement of endosseous implants - A preliminary report on outcome of treatment and patients' satisfaction

During recent decades many surgical techniques have been developed to enlarge the denture-bearing area of the mandible. Most of these techniques improved retention and stability of the lower dentures only temporarily. Since the advent of endosseous implants to stabilize overdentures, combinations of augmentation procedures and placement of endosseous implants have been introduced to restore the severely resorbed mandible. In this study we describe the preliminary results of such a combined approach using sandwich osteotomy with an autogenous bone graft (iliac crest) followed by placement of four endosseous implants in the interforaminal region in 10 women. After a mean follow-up period of 31 months (range 19-57) several variables were measured including condition of the peri-implant tissues, radiographic bone changes and patient satisfaction. The first results indicate that the technique described offers a solid base for implant-stabilized overdentures: no implants were lost, the peri-implant tissues were in good condition, bone loss was limited, and patients were satisfied. Future studies will evaluate the permanence of these results.

Clinical and radiographic characteristics of single-tooth replacements preceded by local ridge augmentation: a prospective randomized clinical trial

OBJECTIVES To assess in a randomized-clinical trial the influence of three augmentation techniques (chinbone with or without a Bio-Gide membrane and Bio-Oss with a Bio-Gide membrane) on the clinical and radiographic characteristics of hard and soft tissues around implants and adjacent teeth in the reconstructed maxillary anterior region, up to 1 year after functional loading. MATERIALS AND METHODS Ninety-three patients requesting single-tooth replacement and presenting with a horizontal (bucco-palatinal) bone deficiency were included. After augmentation, 93 ITI-Esthetic(Plus) implants were placed. Clinical variables, standardized photographs and radiographs were analysed to assess the impact on the levels of the marginal gingiva (MGL) and marginal bone (MBL) around implants and adjacent teeth, viz at pre-augmentation, pre-implantation (TPI) and 1 (T(1)) and 12 (T(12)) months after final crown placement. RESULTS Implant survival was 97.8%. No significant differences were observed in the treatment outcomes of the three augmentation modalities. Combining the three modalities, a slight but significant increase in the implants approximal pocket depth was found between T(1) and T(12). Approximal bone loss at the implant between T(1) and T(12) was 0.14 +/- 0.76 mm (mesial) and 0.14 +/- 0.47 mm (distal); the approximal MGL slightly increased (mesial: 0.24 +/- 0.46 mm, distal: 0.25 +/- 0.66 mm), and the buccal MGL decreased (0.11 +/- 0.61 mm). Bone loss at the adjacent teeth, although minor, was significant between TPI and T(1). No correlations were observed in changes of MBL and MGL. CONCLUSIONS None of the three applied augmentation technique procedures influenced the characteristics of the MGL and MBL or the implant survival of single-tooth replacements. Peri-implant hard and soft tissues were very stable in the first year after loading.

Single-tooth implants with different neck designs: a randomized clinical trial evaluating the aesthetic outcome

AIM To evaluate the aesthetic outcome of single-tooth implants in the aesthetic zone with different neck designs from a professionals and patients perception. MATERIALS AND METHODS Ninety-three patients with a missing anterior tooth in the maxilla were randomly assigned to be treated with an implant with a smooth neck, a rough neck with grooves or a scalloped rough neck with grooves. Implants were installed in healed sites. One year after definitive crown placement (18 months post-implant placement), photographs were taken and the aesthetic outcome was assessed according to two objective aesthetic indexes: pink esthetic score/white esthetic score (PES/WES) and implant crown aesthetic index (ICAI). A questionnaire was used to assess the aesthetic outcome and general satisfaction from a patients perception. standardized radiographs were taken to measure marginal bone level changes. RESULTS One implant was lost. Although there was a significant difference in marginal bone loss between the different implant neck designs (smooth neck 1.19±0.82mm, rough neck 0.90±0.57mm, scalloped neck 2.01±0.77mm), there were no differences in aesthetic outcome. According to the professionals assessments using PES/WES and ICAI, 79.3% and 62% of the cases showed acceptable crown aesthetics, and 59.8% and 56.5% of the cases showed acceptable mucosa aesthetics. Overall, patients were satisfied about the aesthetics of the mucosa (81.5%) and crown (93.3%), and general patient satisfaction was high (9.0±1.0 out of a maximum of 10). According to the professionals assessment, a pre-implant augmentation procedure was associated with less favorable aesthetics of the mucosa. CONCLUSION This study shows that the aesthetics of single-tooth implants in the maxillary aesthetic zone appears to be independent of the implant neck designs applied but dependent on the need for pre-implant surgery.

Maxillary sinus floor elevation surgery with BioOss® mixed with a bone marrow concentrate or autogenous bone: test of principle on implant survival and clinical performance

The purpose of this study was to assess implant survival and 1-year clinical performance of implants placed in the posterior maxilla that had been subjected to maxillary sinus floor elevation surgery with bovine bone mineral (BioOss®) mixed with autogenous bone marrow concentrate or autogenous bone. In a randomized, controlled, split-mouth design study, a bilateral sinus floor augmentation procedure was performed in 12 edentulous patients. At random, one side was treated with BioOss® seeded with an iliac crest bone marrow concentrate enriched in mesenchymal stem cells (test side) and the other with BioOss® mixed with autogenous bone (control side). Three to four months after augmentation, 66 implants were placed. Implant survival, plaque, gingival, and bleeding indices, probing depth, and peri-implant radiographic bone levels were assessed at baseline and 12 months after functional loading. During osseointegration, three implants failed on the test side (two patients) and no implants failed on the control side, resulting in 3-month survival rates of 91% and 100%, respectively. No implants were lost after functional loading and no differences in soft tissue parameters or peri-implant bone loss were observed between the control and test sides. After 1 year in function, no clinically relevant differences were observed regarding soft tissue parameters or peri-implant bone loss.

Reconstruction of the extremely atrophied mandible with iliac crest onlay grafts followed by two endosteal implants: a retrospective study with long-term follow-up

Treatment outcomes of implant-retained lower dentures on two endosseous implants placed in severely atrophied mandibles after reconstruction with iliac crest onlay grafts were assessed in a retrospective observational study. All consecutive patients treated between 2000 and 2007 were recalled in 2012 (n=40). Survival of the implants, the condition of hard and soft peri-implant tissues, and patient satisfaction were scored. One implant was lost after 5.5 years. The mean mandibular symphysis height was 8.9±2.2, 16.4±2.7, 15.7±2.7, and 15.4±2.5mm at intake, after augmentation, after implantation, and at the last recall visit, respectively. Mean radiographic peri-implant bone loss was 0.6±0.7mm. Mean clinical index scores were very low. Patient satisfaction was high. Surgical complications related to the donor site were seroma (n=1), haematoma (n=2), and sensory disturbance of the lateral femoral cutaneous nerve (n=1); all had resolved before placement of the implants. Eleven patients reported postsurgical sensory disturbances of the mental nerve, of whom five still experienced some sensory disturbance at the last recall visit. Augmentation of the extremely resorbed mandible with an iliac crest onlay graft followed by placement of two implants 4 months later provides a solid basis for a bar-retained overdenture with favourable clinical and radiographic results.

Short implants with a nanometer-sized CaP surface provided with either a platform-switched or platform-matched abutment connection in the posterior region: a randomized clinical trial

OBJECTIVE To assess the performance of short nanorough implants (8.5 mm in length) provided with either a platform-matched or a platform-switched implant-abutment connection, placed in the resorbed posterior region of partially dentate patients. MATERIALS AND METHODS A total of 149 implants with a dual-acid surface and a discrete crystalline deposition of nanometer-sized CaP particles, with either a platform-matched (control) or a platform-switched implant-abutment connection (test) were placed (randomly assigned) in 92 patients. Follow-up visits were conducted 1 month and 1 year after placing the implant crown. Outcome measures were implant survival, radiographic peri-implant bone loss, clinical parameters, and patients satisfaction. RESULTS One year after loading, 6 of 76 implants in the control group (survival 92.1%) and 3 of 73 implants in the test group (survival 95.9%) were lost (P = 0.33). Radiographic bone loss around test implants (0.50 ± 0.53 mm) was significantly less than around control implants (0.74 ± 0.61 mm; P < 0.005). With regard to implant survival, clinical parameters, and patients satisfaction, no significant differences were observed between test and control group. CONCLUSIONS For teeth replacements in the resorbed posterior region of partially dentate patients, short implants with a platform-switched implant-abutment connection showed significantly less peri-implant bone loss after 1 year in function, while implant survival, clinical parameters, and patients satisfaction were independent of the implant-abutment connection design.

Maxillary anterior and mandibular posterior residual ridge resorption in patients wearing a mandibular implant‐retained overdenture

The mandibular implant-retained overdenture could improve masticatory function compared to the conventional complete denture. However, increased forces exerted by the overdenture could increase residual ridge resorption of the maxillary anterior and mandibular posterior areas. The aim of this study was to compare the effect of the mandibular implant-retained overdenture using two or four dental implants, or the conventional complete denture on resorption of the residual ridge of the maxillary anterior and mandibular posterior areas over a period of 10 years. In total, 120 patients, 30 patients treated with an overdenture on two implants (two-implant group), 30 patients with an overdenture on four implants (four-implant group) and 60 patients treated with a conventional full denture (conventional group), participated in this study. On panoramic radiographs, made before and 10 years after treatment, proportional area measurements were applied to determine changes in bone height. After 10 years, a statistically significant amount of bone resorption had occurred in the anterior maxilla in the two-implant group and in the four-implant group. A significant amount of bone resorption had occurred in the posterior mandible in all three groups. There were no statistically significant differences between the groups in both areas. Patients presented large individual differences. It is concluded that patients rehabilitated with implant-retained mandibular overdentures are not subjected to more residual ridge resorption in the anterior maxilla when compared to patients wearing a conventional full denture. Regarding the mandibular posterior residual ridge, resorption was irrespective of wearing an implant-retained mandibular overdenture or a conventional mandibular denture.

Maxillary overdentures supported by four or six implants in the anterior region

Abstract Objective To compare a four‐ and six‐implant maxillary overdenture after an observation period of 5 years. Material and methods Fifty subjects with functional problems concerning their maxillary denture, who had ample bone volume in the anterior region to place four or six implants, were included and randomly assigned to either group. Implant and overdenture survival, clinical performance, marginal bone loss and patient satisfaction were assessed. Results Forty‐six patients completed the 5‐year follow‐up. One implant failed in the six implants group (99.2% survival) and none in the four implants group (100% survival). No overdentures had to be replaced during the observation period and the number of complications was limited. Clinical function was good, with no difference in clinical parameters between the groups. Mean marginal bone resorption was 0.50 ± 0.37 and 0.52 ± 0.43 mm in the four and six implant group respectively. Conclusion In patients with functional complaints of their maxillary denture, bar‐supported overdentures on four implants in the anterior maxillary region were not inferior to overdentures supported by six implants after 5 years of function. Implant survival and patient satisfaction were high, clinical parameters favourable, bone loss and complications to the denture were minor in both groups (Clinical trial registration number: NTR2969).