Digitally designed surgical guides for placing extraoral implants in the mastoid area

PURPOSE

When planning implant therapy, knowledge of the bone volume in the implant area is needed to plan and place implants in the most appropriate locations from the prosthetic and surgical perspectives. Commercial software for digital planning of implants in the craniofacial region is not yet available. This article describes a method that enables digital planning of extraoral implants in the mastoid region utilizing commercially available computer-aided design (CAD) software and rapid-prototyping techniques to manufacture a corresponding surgical guide.

MATERIALS AND METHODS

With the aid of CAD software designed for reverse engineering and three-dimensional animation, digital implant planning based on cone beam computed tomography (CBCT) scanning was performed. On the basis of this planning, surgical guides were digitally designed to facilitate the placement of dental implants in the mastoid area. The guides were fabricated using rapid prototyping. The appropriateness of the digitally designed surgical guides for placing extraoral implants was tested on six human cadaver heads with simulated bilateral ear defects. After implant placement, a second CBCT scan was performed to compare preoperative planning with the actual postoperative implant positions.

RESULTS

Twenty-four implants were placed. The surgical guide helped the surgeon to place the implants at the preoperatively planned positions. Comparison of the CBCT scans revealed that adequate accuracy of implant placement was achieved, both for deviation of the neck (1.56 ± 0.56 mm) and the tip (1.40 ± 0.53 mm) of the implant, and for deviation of the angulation of the implant (0.97 ± 2.33 deg).

CONCLUSION

The presented method for digitally planning extraoral implants in the mastoid area and designing surgical guides allows for placement of implants in the mastoid area in close proximity to the preoperatively planned implant position. The actual implant positions were satisfactory both surgically and prosthetically.

Digitally designed surgical guides for placing implants in the nasal floor of dentate patients: a series of three cases

PURPOSE

Insight into the bone volume and position of natural teeth is essential when placing implants to retain nasal prostheses. This paper describes a series of three cases in which a new method was applied for implant placement in the nasal floor of dentate patients using digital planning techniques.

MATERIALS AND METHODS

With the aid of computer software, digital planning of implants in the nasal floor based on cone beam computed tomography was performed. Next, surgical guides for implant placement were digitally designed and fabricated using rapid prototyping.

RESULTS

In all three patients, implants could be placed and nasal prostheses could be manufactured as planned. All anterior teeth remained vital. Analysis of planning and post-implant placement cone beam computed tomography scans revealed high accuracy of implant placement.

CONCLUSION

The applied method allows for reliable implant placement in close proximity to the preoperatively planned implant position.

Performance of the Straumann Bone Level Implant system for anterior single-tooth replacements in augmented and nonaugmented sites: a prospective cohort study with 60 consecutive patients

AIM

The purpose of this prospective study was to evaluate radiographic, clinical and aesthetic outcomes and patient satisfaction of cases treated with platform-switched single implant restorations in the aesthetic region of the maxilla. Furthermore, the influence of an augmentation procedure 3 months before implant placement and the type of restoration (screw-retained vs. cement-retained) was evaluated.

MATERIAL AND METHODS

Sixty patients with a missing anterior tooth in the maxilla were treated with a Straumann Bone Level Implant. Bone augmentation was performed in 29 patients at 3 months before implant placement. Implants were loaded after 3 months of submerged healing. Follow-up was conducted at 7 and 18 months after implant placement. Peri-implant mucosa and implant crown aesthetic outcomes were determined using the Implant Crown Aesthetic Index (ICAI) and the Pink Esthetic Score-White Esthetic Score (PES-WES).

RESULTS

No implants were lost. At 18 months after implant placement, mean bone level change was -0.10 ± 0.27 mm and mean probing pocket depth was 2.57 mm. No differences were found between augmented and nonaugmented sites (P = 0.28). The ICAI indicated satisfactory mucosa and crown aesthetics in 67% and 75% of the cases, respectively, while the PES score was 14.4. ICAI mucosa (P = 0.004) and PES (P = 0.02) scores were significantly less favourable for augmented sites compared with nonaugmented sites. Patient satisfaction was high (8.9 ± 1.1 on VAS-score).

CONCLUSIONS

From the present prospective, clinical study, it can be concluded that the Straumann Bone Level Implant shows an excellent survival rate, marginal bone stability and good clinical and aesthetic results. Bone augmentation before implant placement does not lead to more marginal bone loss. However, less favourable pink aesthetic outcomes were found in augmented sites compared with nonaugmented sites, while no differences were found between cement-retained and screw-retained restorations.

Impact of platform switching on inter-proximal bone levels around short implants in the posterior region; 1-year results from a randomized clinical trial

AIM

To assess the outcome of short implants (8.5 mm) supplied with a conventional platform-matched implant-abutment connection or a platform-switched design.

MATERIALS AND METHODS

Eighty patients with one or more missing teeth in the posterior zone were randomly assigned to be treated with implants with either a conventional (control) or a platform-switched (mismatch 0.35-0.40 mm) implant-abutment connection (test). Follow-up visits were conducted 1 month and 1 year after placing the implant crown. Outcome measures were inter-proximal bone loss, using standardized peri-apical radiographs, implant survival, clinical parameters and patients' satisfaction.

RESULTS

One year after loading, inter-proximal bone loss around test implants (0.51 ± 0.51 mm) was significantly less than around control implants (0.73 ± 0.48 mm) (p = 0.011). Moreover, bone loss was less around 1 versus 2 adjacent implants (p = 0.001), in both the test (0.29 ± 0.36 versus 0.71 ± 0.55 mm) and control (0.46 ± 0.42 versus 0.88 ± 0.45 mm) group. With regard to implant survival, clinical parameters and patients' satisfaction no differences were observed between the test and control group.

CONCLUSION

This study suggested that crestal bone resorption may be reduced by platform switching. One year after loading, inter-proximal bone levels were better maintained at implants restored according to the platform switching concept.

Malpositioned osseointegrated implants relocated with segmental osteotomies: a retrospective analysis of a multicenter case series with a 1- to 15-year follow-up

PURPOSE

This multicenter case series evaluates retrospectively the clinical outcomes of malpositioned implants surgically relocated in a more convenient position by segmental osteotomies.

MATERIALS AND METHODS

Authors who published, on indexed journals or books, works about malpositioned implant correction by segmental osteotomies were contacted. Five centers, out of 11 selected, accepted to participate in this study. The dental records of patients who underwent implant relocation procedures were reviewed. Implant survival rates were analyzed and a blinded assessor examined clinical photos and periapical radiographs to evaluate esthetic outcome (pink esthetic score [PES]) and changes of marginal bone level over time. Patients were requested to fill a verbal rating scale form about discomfort, compliance, and satisfaction related to the procedure.

RESULTS

Fifteen malpositioned implants relocated by segmental osteotomies were followed for a period ranging from 1 to 15 years (mean 6.0 ± 3.9 years). The overall implant survival rate from baseline to the last follow-up visit was 100%. The mean marginal bone loss was 0.36 mm at the 12-month follow-up visit and no relevant further changes were observed at the following examinations. Significant esthetic improvement was recorded at 1-year examination with PES evaluation (p < .0001). Patients' feedback described this procedure as not excessively invasive and uncomfortable, reporting a high final satisfaction rate.

CONCLUSIONS

The present study suggests that implant relocation with segmental osteotomies could be an effective alternative method to correct the position of unrestorable malpositioned implants in a single-stage surgery.

Maxillary sinus floor augmentation surgery with autogenous bone grafts as ceiling: a pilot study and test of principle

BACKGROUND

Studies have pointed out that the mere elevation of the maxillary sinus membrane might suffice to allow for bone formation indicating the additional use of augmentation materials to be redundant.

PURPOSE

The purpose of this study was to assess whether elevation of the sinus mucosal lining combined with applying an autologous bone graft as a ceiling and placement of a short implant would allow for bone formation around the implant thus surpassing the need for applying augmentation materials around the installed implants.

MATERIALS AND METHODS

Fourteen consecutive patients were subjected to maxillary sinus floor elevation surgery and simultaneous placement of an implant. Using the lateral bone-wall window technique, the membrane was exposed and elevated. Next, a bone graft taken from the zygomatic rim was placed as a ceiling above the inserted implant to ensure that the sinus membrane would not collapsed around a significant part of the implant. Finally, the bone window was returned in place. After connecting the healing abutment, the wound was closed.

RESULTS

All implants were stable and no implants were lost. There were no complications after harvesting the bone graft. Radiographic evaluation showed a bone gain of 3.2 ± 0.9 mm after 3 months and 3.6 ± 0.9 mm after 1 year. Less than 6% of the implant was not covered by bone after 1 year.

CONCLUSION

Maxillary sinus membrane elevation and simultaneous placement of short endosseous implants with a bone graft as a ceiling on top of the implant result in predictable bone formation around the implant and good osseointegration on radiographs.

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.

A low-grade myofibroblastic sarcoma in the abdominal cavity

Background

Rhabdomyosarcoma is the most common malignant tumor in the nasal and paranasal sinus area at childhood. Multimodal treatment for this disorder has severe side effects due to normal tissue damage. As a result of this treatment, facial growth retardation and oral abnormalities such as malformation of teeth and microstomia can cause esthetic and functional problems.

Case reports

Two cases are presented of patients with severe midfacial hypoplasia and reduced oral function as a result of treatment of rhabdomyosarcoma of the nasopharyngeal and nasal–tonsil region. With a combined surgical (osteotomy, distraction osteogenesis, implants) and prosthetic (implant-based overdenture) treatment, esthetics and function were improved.

[Complications in patients with oral implants. Recommendations for routine preventive inspections]

Oral implantology is a very fast growing and dynamic area of oral healthcare, carried out by an increasing number of oral healthcare providers. Recommendations for routine preventive inspections are needed to control and monitor the quality of treatment. Routine preventive inspection can be divided into inspection of the peri-implant hard and soft tissues and inspection of the prosthetic construction. The most frequently occurring complications, each with its own treatment, are peri-implant mucositis, peri-implantitis, recession of peri-implant tissues, the loosening or fracturing of overdenture attachment components, deterioration of the fit of overdentures, and the loosening of the screw with which a crown is secured on an implant or implant abutment. Carrying out routine preventive inspections will make it possible to detect and treat complications in a timely fashion.

Safe harvesting of outer table parietal bone grafts using an oscillating saw and a bone scraper: a refinement of technique for harvesting cortical and "cancellous"-like calvarial bone

Calvarial bone is a readily available source of bone for preimplantation augmentation procedures of the alveolar process. However, the calvaria consist mostly of cortical bone, and cancellous bone of the diploic space is scarce. A bone scraper (Safescraper Twist; META, Reggio Emilia, Italy) was used to create a beveled trough around the calvarial outer table graft to facilitate its removal with an oscillating saw. Using the scraper, copious amounts (>10 mL) of "cancellous"-like bone could be collected. This new application of the Safescraper Twist obviated milling down additional cortical pieces.

Addressing the atrophied mandible: a proposal for a treatment approach involving endosseous implants

PURPOSE

Since the introduction of endosseous dental implants, the treatment concepts for management of the edentulous mandible have changed drastically. Reconstructive, preprosthetic 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 placement of dental implants at the, from a prosthetic point of view, optimal position. Moreover, the currently applied implant based prosthodontic concepts for the edentulous mandible are based on prospective randomized clinical trials comparing the treatment outcome of a variety of treatment modalities. This study reviews the various treatment concepts that are currently in use to rehabilitate the extremely atrophied mandible.

MATERIALS AND METHODS

A comprehensive review of human studies published in the international peer-reviewed literature up to March 2010 regarding procedures related to implant treatment in the extremely atrophied edentulous mandible was made. A MEDLINE search was completed, along with a manual search, to locate relevant literature.

RESULTS

There are advantages and disadvantages that are specific to removable implant-supported overdentures and fixed implant-supported full prostheses. The choice of an overdenture or a fixed full-arch prosthesis should be made on an individual basis. Once this choice has been made, the surgical procedure and the number of implants to be placed have to be determined.

CONCLUSION

On the basis of the best evidence currently available, a treatment concept is proposed on how to deal with the edentulous mandible in order to provide patients with a mandibular overdenture supported by endosseous implants.

A double-blind randomized controlled trial (RCT) of Titanium-13Zirconium versus Titanium Grade IV small-diameter bone level implants in edentulous mandibles--results from a 1-year observation period

BACKGROUND

The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two-implant overdenture has been recommended as the standard of care. The use of small-diameter implants may extend treatment options and reduce the necessity for bone augmentation. However, the mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable.

PURPOSE

This randomized, controlled, double-blind, multicenter study investigated in a split-mouth model whether small-diameter implants made from Titanium-13Zirconium alloy (TiZr, Roxolid™) perform at least as well as Titanium Grade IV implants.

METHODS AND MATERIALS

Patients with an edentulous mandible received one TiZr and one Ti Grade IV small-diameter bone level implant (3.3 mm, SLActive®) in the interforaminal region. The site distribution was randomized and double-blinded. Outcome measures included change in radiological peri-implant bone level from surgery to 12 months post-insertion (primary), implant survival, success, soft tissue conditions, and safety (secondary).

RESULTS

Of 91 treated patients, 87 were available for the 12-month follow-up. Peri-implant bone level change (-0.3 ± 0.5 mm vs -0.3 ± 0.6 mm), plaque, and sulcus bleeding indices were not significantly different between TiZr and Ti Grade IV implants. Implant survival rates were 98.9 percent and 97.8 percent, success rates were 96.6 percent and 94.4 percent, respectively. Nineteen minor and no serious adverse events were related to the study devices.

CONCLUSION

This study confirms that TiZr small-diameter bone level implants provide at least the same outcomes after 12 months as Ti Grade IV bone level implants. The improved mechanical properties of TiZr implants may extend implant therapy to more challenging clinical situations.

Applicability of equine hydroxyapatite collagen (eHAC) bone blocks for lateral augmentation of the alveolar crest. A histological and histomorphometric analysis in rats

This study assessed the mechanical characteristics, biocompatibility and osteoconductive properties of an equine hydroxyapatite collagen (eHAC) bone block when applied as a bone substitute for lateral augmentation of rat mandible. 96 rats underwent lateral augmentation of the mandible, using two substitute bone blocks (eHAC or Bio-Oss spongiosa) or autologous bone grafts. Signs of inflammation, amount of bone formation and ingrowth of bone into the bone blocks were assessed at 1 and 3 months. eHAC blocks were mechanically rigid and could be fixed firmly and easily. Bio-Oss spongiosa blocks were brittle and fixation was difficult. eHAC and Bio-Oss spongiosa blocks were biocompatible and induced few or no signs of inflammation. Inflammation prevalence between the groups was not statistically different. Bone formation and bone growth into the blocks was significantly higher in eHAC than Bio-Oss spongiosa blocks, but lower than in autologous bone grafts (after 1 and 3 months). Regression analysis showed that the autologous bone graft predicted new bone formation at both time points. The eHAC block was only a predictor at 1 month; a trend was found at 3 months. The application of biodegradable membranes was not related to more bone ingrowth.

Five-year follow-up of oral functioning and quality of life in patients with oral cancer with implant-retained mandibular overdentures

BACKGROUND

The purpose of this prospective study was to assess the quality of life (QOL) and oral functioning of patients with oral cancer up to 5 years after prosthodontic rehabilitation with mandibular implant-retained overdentures.

METHODS

Fifty patients who had received implants during ablative surgery were evaluated by standardized questionnaires before and after oncological and prosthetic treatment.

RESULTS

In 20 of 24 surviving patients, the dentures were functional after 5 years. In these survivors, oral function remained unchanged during this period. In the 6 patients with concurrent comorbidity, global health and QOL had deteriorated, while in the patients without comorbidity, global health and QOL were very high. Five-year survivors had a higher global health and better oral functioning at the 1-year evaluation than nonsurvivors.

CONCLUSION

Oral function and denture satisfaction were high and did not change over time for survivors. Deterioration in overall global health and QOL was associated with concurrent comorbidity.

Benefits of dental implants installed during ablative tumour surgery in oral cancer patients: a prospective 5-year clinical trial

OBJECTIVE

This prospective study assessed treatment outcome and patient satisfaction of oral cancer patients with a mandibular overdenture on implants up to 5 years after treatment.

MATERIALS AND METHODS

At baseline, 50 consecutive edentulous oral cancer patients, in whom prosthetic problems were expected after oncological treatment, were evaluated by standardized questionnaires and clinical assessments. All implants were installed during ablative tumour surgery in native bone in the interforaminal area. About two-thirds of the patients (n=31) had radiotherapy post-surgery (dose >40 Gy in the interforaminal area).

RESULTS

At the 5-year evaluation, 26 patients had passed away and four patients had to be excluded from the analyses, because superstructures were not present, due to persistent local irritation (n=2), loss of three implants (n=1) and the impossibility of making an overdenture related to tumour and oncological surgery-driven anatomical limitations (n=1). In the remaining 20 patients, the prosthesis was still in function (76 implants). During the 5-year follow-up, total 14 implants were lost, 13 in irradiated bone (survival rate 89.4%, dose >40 Gy) and one in non-irradiated bone (survival rate 98.6%). Peri-implant tissues had a healthy appearance and remained healthy over time. Patients were satisfied with their dentures.

CONCLUSIONS

It was concluded that oral cancer patients can benefit from implants installed during ablative surgery, with a high survival rate of the implants, a high percentage of rehabilitated patients and a high denture satisfaction up to 5 years after treatment.