Effect of Drilling Preparation on Immediately Loaded Implants: An In Vivo Study in Sheep

PURPOSE

To determine the biologic and biomechanical effects of two implant drilling protocols on the cortical bone around implants subjected to immediate loading.

MATERIALS AND METHODS

A total of 48 implants were inserted into the mandibles of six sheep following one of two drilling protocols: undersized preparation (US; n = 24) and nonundersized preparation (NUS; n = 24). Immediately after implant insertion, an abutment was placed on each implant and 36 implants were subjected to 10 sessions of dynamic vertical loads (1,500 cycles, 1 Hz) of 25 N or 50 N. Insertion torque value (ITV) was recorded at implant installation. Resonance frequency analysis (RFA) was measured at implant insertion and at each loading session. Fluorochrome was administered at day 17, and the animals were euthanized after 5 weeks. The removal torque values (RTVs) were measured, and samples underwent histomorphometric, μCT (microcomputed tomography), and fluorescence image acquisition analyses. The bone volume density (BV/TV), bone-to-implant contact (BIC), bone area fraction occupancy (BAFO), and fluorochrome stained bone surface (MS) were calculated. A linear mixed model analysis was performed, and Pearson paired correlation was calculated.

RESULTS

Five implants from the NUS group failed, with a mean ITV of 8.8 Ncm and an RFA value of 57. The mean ITVs for US group and NUS group were 80.5 (± 14) Ncm and 45.9 (± 25) Ncm, respectively (P < .001). No differences were noted in the RFA values from the time of implant insertion until the end of the study. No differences in RTV, BV/TV, BAFO, or MS were observed between the groups. Intense new bone formation took place in the NUS group implants that were subjected to load.

CONCLUSIONS

Undersized preparation of cortical bone ensured a greater BIC compared to a nonundersized preparation. Moreover, this study demonstrated that immediate loading did not interfere with the osseointegration process, but loading induced intense new bone formation in the NUS group. It is not recommended to immediately load the implants when the clinically perceived primary stability is lower than an ITV of 10 Ncm and an RFA value of 60. Int J Oral Maxillofac Implants 2023;38:607-618. doi: 10.11607/jomi.9949.

Effect of antibiotic prophylaxis in dental implant surgery: A multicenter placebo‐controlled double‐blinded randomized clinical trial

Background

Purpose

Materials and Methods

Results

Conclusion

The use of implant-level connection in screw-retained fixed partial dentures: A 3-year randomised clinical trial

OBJECTIVES

This randomised controlled trial compares the 3-year outcomes, that is, marginal bone-level (MBL) changes and clinical parameters, between an abutment-level (AL) and implant-level (IL) connection for implants with an internal conical connection (ICC) supporting a screw-retained fixed partial denture.

MATERIAL AND METHODS

Fifty patients with 119 implants were randomly allocated to either the AL or IL group. Radiographic and clinical examinations were performed after one, two, and 3 years. A linear mixed model was used to evaluate the differences between groups.

RESULTS

The MBL change was not significantly different between the groups at any point. The MBL was 0.12 ± 0.31 mm (AL) and 0.23 ± 0.26 mm (IL) after 1 year; 0.15 ± 0.34 mm (AL) and 0.17 ± 0.22 mm (IL) after 2 years; 0.18 ± 0.39 mm (AL) and 0.15 ± 0.21 mm (IL) after 3 years. The bleeding on probing was 43.44 ± 39.24% (AL) and 58.19 ± 41.20% (IL) after 1 year; 35.78 ± 39.22% (AL) and 50.43 ± 41.49% (IL) after 2 years; 51.27 ± 44.63% (AL) and 49.57 ± 37.31% (IL) after 3 years and was significantly different (p = .025) between 1 and 2 years. The probing depth showed a significant difference at each time point while the plaque was not significant between the groups. The overall technical, biological and prosthetic complication rates were 5.04%, 3.36%, and 16.00%, respectively.

CONCLUSIONS

The MBL change was similar in the groups. The slight differences in the soft tissue complications between the groups are likely not of clinical relevance. An IL connection is considered to be a valid alternative to an AL set-up in ICC implants.

Estimation of Blood Loss in Oral and Maxillofacial Surgery by Measurements of Low Haemoglobin Levels in Mixtures of Blood, Saliva and Saline: a Laboratory Study

Objectives

Estimating blood loss is an important factor in several surgical procedures. The accuracy of blood loss measurements in situations where blood is mixed with saliva and saline is however uncertain. The purpose of this laboratory study was to ascertain if blood loss measurements in mixtures of blood, saline, and saliva are reliable and could be applicable in a clinical setting.

Material and Methods

Venous blood and resting saliva were collected from six volunteers. Saliva, saline, and combinations thereof were mixed with blood to obtain different concentrations. A portable spectrophotometer was first used to measure the haemoglobin concentration in undiluted venous blood followed by measurements of the haemoglobin concentration after each dilution. To examine the strength of linear relationships, linear regression and Pearson correlations were used.

Results

The measurements of haemoglobin concentrations in mixtures of blood, saline, and saliva were proven to be accurate for haemoglobin measurements > 0.3 g/dl (correlation = 0.986 to 1). For haemoglobin measurements < 0.3 g/dl, a small increase in haemoglobin values were reported, which was directly associated to the saliva concentration in the solution (correlation = 0.983 to 1). This interference of saliva was significantly eliminated by diluting the samples with saline, mimicking the clinical situation.

Conclusions

The results suggest that a portable spectrophotometer can be used clinically to preoperatively measure the haemoglobin value of a venous blood sample and postoperatively measure the haemoglobin value of the collected liquids, including shed blood, thereby achieving a highly accurate method of measuring blood loss during oral and maxillofacial surgery.

Impact of a Hydrophilic Dental Implant Surface on Osseointegration: Biomechanical Results in Rabbit

This study aimed to evaluate the effect of surface hydrophilicity on the biomechanical aspects of osseointegration of dental implants in the tibia and femur of rabbits. Forty-eight mature female New Zealand White rabbits were included, and 96 commercially pure, Grade 4, titanium dental implants (control group), and 96 implants of same macro geometry with the hydrophilic surface (test group) were used in this study. One osteotomy was performed in each tibia and femur on both sides of the rabbit, and four implants were placed in each rabbit. Control and test groups were randomly allocated on the left and right sides. During surgery, insertion torque (ITQ) value of the complete implant placement was recorded. After healing periods of 0, 2, 4, and 8 weeks after surgery, implant stability quotient (ISQ) value, and removal torque (RTQ) values were measured. No statistical difference was observed for ITQ, for ISQ and for RTQ between the control group and test group in tibia/femur for all time periods. The effect of hydrophilic properties on moderately roughened surfaces has no impact in terms of biomechanical outcomes (ISQ values and RTQ values) after a healing period of 2 to 8 weeks in rabbit tibias /femurs.

Fixed full-arch maxillary prostheses supported by four versus six implants with a titanium CAD/CAM milled framework: 3-year multicentre RCT

OBJECTIVES

This RCT compares marginal bone level (MBL) change and the clinical parameters after a 3-year function in maxillary implant-supported fixed complete dentures (FCDs) treated with four-implants (4-I) or six-implants (6-I).

MATERIAL AND METHOD

Three centres treated 56 patients with 280 implants allocated to the 4-I or 6-I group. Radiographic and clinical examinations were performed. The primary outcome was to investigate MBL change between the groups.

RESULTS

Implant survival rates were 100% and 99% in the 4-I and 6-I groups, respectively. Considering the clustering effects, the MBL change was not significantly different between the groups over the 3-year follow-up. The MBL in the 4-I group was 0.30 ± 0.50 mm at baseline, 0.24 ± 0.31 mm at 1 year and 0.24 ± 0.38 mm at 3 years. In the 6-I group, MBL was 0.14 ± 0.32 mm at baseline, 0.16 ± 0.35 mm at 1 year and 0.12 ± 0.26 mm at 3 years. There was a statistically significant difference between the groups at BL and 3Y. No significant differences between the groups were reported for clinical parameters at each time point as well as in between the visits. The technical and biological complications rates were 1.6% and 6.0%, respectively. Prosthetic complications affected 25 FCDs (47.2%).

CONCLUSION

Marginal bone level change revealed a stable condition in the 3-year period in the two groups. Few technical and biological complications occurred apart from the chipping/fracture of the prosthetic teeth. Four-implant is a feasible solution if the rehabilitation is oriented towards the most cost-effective treatment and towards avoiding bone augmentation procedures. Clinicians have to consider the potential required visits for prosthetic maintenance.

Craniofacial Height in Relation to Cross-Sectional Morphology of the Anterior Maxilla: An Anatomical Consideration in Implant Therapy

PURPOSE

Patients who have a vertical growth pattern are more prone to complete alveolar bone growth later and run a higher risk for inhibition of growth and infraposition after implants have been placed. Moreover, it has been suggested for the same category of patients that craniofacial height may influence the alveolar bone morphology of the anterior maxilla during growth. Hence, it is important to identify such patients early when considering implant treatment in young patients. The purpose of this study was to investigate the height and width of the alveolar bone in the anterior maxilla in subjects with different craniofacial heights to assess if there is a relation between craniofacial height and the dimensions of the alveolar bone in the anterior part of the maxilla.

MATERIALS AND METHODS

Measurements on cephalograms and cone beam computed tomography (CBCT) images of the maxilla from 180 fully dentate subjects were analyzed and categorized into three angle groups based on the craniofacial height: low-, normal-, and high-angle groups. Measurements of the alveolar bone were taken interradicular, at six reference points distributed between the first premolar regions in the maxilla. The height and width of the alveolar bone were measured with a standardized technique at 3, 6, 9, and 12 mm from the top of the alveolar process.

RESULTS

Significant differences were found regarding the height of the alveolar bone in all the subgroups and regarding the width in the 9- and 12-mm subgroups, and between low-/normal- and low-/high-angle groups, where the high-angle group represented the thinnest alveolar bone. A significant difference was found between male and female patients concerning all dimensions of the alveolar bone.

CONCLUSION

There is a relation between craniofacial height and the dimensions of the alveolar bone in the anterior part of the maxilla. Craniofacial height is an important factor to analyze when implant treatment is considered in the maxillary anterior region. This identification can preferably be carried out early in young patients who are still growing when various treatment options can still be considered.

Is there a difference in judgement of facial appearance depending on ethnic background? Photographic evaluation of facial appearance in orthognathic surgery

Is there a variation in facial ideals depending on ethnic background that affects judgements of outcome in orthognathic surgery? How does the evaluation correlate with patient-reported outcome measures? Two evaluation panels, Singaporean and Swedish, judged photographs of patients undergoing orthognathic surgery taken before and after operation. Improvement in facial aesthetics was calculated between the two ratings. The result was compared between the panels and correlated with health-related quality of life (QoL) measures. Thirty male and 27 female patients aged between 18 and 28 years (mean 21) were included, and 52 subjects were eligible for comparison of health-related QoL. The photographic evaluation showed that both panels judged there to be significant improvement in facial aesthetics after treatment (p<0.001). The Singaporean panel rated the overall facial appearance higher than the Swedish panel when evaluating photographs both before (p=0.025) and after (p=0.032) operation. Improvement of the overall facial appearance showed no significant difference between the panels (p>0.30). No correlation between health-related QoL and improvement of facial appearance was found by either panel. Subjective evaluation of facial aesthetics in orthognathic surgery is unaffected by the observer's ethnic origin. Independently of their ethnicity, the evaluation juries found that facial aesthetics improved after orthognathic surgery. Improvement reported by the juries corresponded to that reported by patients.

Impact of salivary contamination during placement of implants with simultaneous bony augmentation in iliac bone in sheep

Our aim was to investigate the possible impact of contamination with saliva on osseointegration during placement of implants with simultaneous bone augmentation. Six hemispheric shape bone defects (8mm in diameter×4mm deep) were prepared in each iliac bone of six sheep. A dental implant (2.9mm in diameter×10mm long) was placed in the centre of each defect, and then pairs of defects were filled with one of the following bone augmentation materials: autogenous bone, autogenous bone plus bovine bone, or resorbable biphasic ceramic bone substitute. One site in each augmentation group was impregnated with saliva (contaminated group), while the other was not (non-contaminated group). Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) within implant threads were measured after a healing period of five weeks, both in respect of the implant inserted in the augmented bone and in that inserted in the residual bone. Overall results showed that there was a significant difference between the contaminated and non-contaminated group for BIC in the augmented implant (p=0.028), while there were no significant differences in the implant in residual bone (p=0.722). For BAFO, there were no significant differences between the contaminated and non-contaminated groups among the different augmentation materials. The results showed that contamination with saliva during placement of an implant with simultaneous bone augmentation had a serious deleterious effect on osseointegration of the aspect of the implant within the augmented defect. Contamination with saliva during placement of an implant with simultaneous bone augmentation should therefore be avoided.

Intraosseous Temperature Change during Installation of Dental Implants with Two Different Surfaces and Different Drilling Protocols: An In Vivo Study in Sheep

Background: The intraosseous temperature during implant installation has never been evaluated in an in vivo controlled setup. The aims were to investigate the influence of a drilling protocol and implant surface on the intraosseous temperature during implant installation, to evaluate the influence of temperature increase on osseointegration and to calculate the heat distribution in cortical bone. Methods: Forty Brånemark implants were installed into the metatarsal bone of Finnish Dorset crossbred sheep according to two different drilling protocols (undersized/non-undersized) and two surfaces (moderately rough/turned). The intraosseous temperature was recorded, and Finite Element Model (FEM) was generated to understand the thermal behavior. Non-decalcified histology was carried out after five weeks of healing. The following osseointegration parameters were calculated: Bone-to-implant contact (BIC), Bone Area Fraction Occupancy (BAFO), and Bone Area Fraction Occupancy up to 1.5 mm (BA1.5). A multiple regression model was used to identify the influencing variables on the histomorphometric parameters. Results: The temperature was affected by the drilling protocol, while no influence was demonstrated by the implant surface. BIC was positively influenced by the undersized drilling protocol and rough surface, BAFO was negatively influenced by the temperature rise, and BA1.5 was negatively influenced by the undersized drilling protocol. FEM showed that the temperature at the implant interface might exceed the limit for bone necrosis. Conclusion: The intraosseous temperature is greatly increased by an undersized drilling protocol but not from the implant surface. The temperature increase negatively affects the bone healing in the proximity of the implant. The undersized drilling protocol for Brånemark implant systems increases the amount of bone at the interface, but it negatively impacts the bone far from the implant.

Implant vs abutment level connection in implant supported screw-retained fixed partial dentures with cobalt-chrome framework: 1-year interim results of a randomized clinical study

BACKGROUND

Screw-retained fixed partial dentures (FPD) have shown a lower incidence of biologic complications and an easier retrievability compared with cemented FPD.

PURPOSE

To compare the marginal bone loss at conical connection implant restored with a screw retained cobalt-chrome FPD in an implant-level (IL) or an abutment-level (AL) setup.

MATERIALS AND METHODS

Patients with at least two adjacent missing teeth were randomly allocated to be restored with IL or AL FPD. Periapical radiographs and clinical examination were taken at implant placement, prosthetic connection, 6 and 12 months to evaluate marginal bone loss (MBL), and soft tissue conditions. Complications were used to calculate prognostic indexes.

RESULTS

Fifty patients were treated with 50 FPD supported by 119 implants. The difference of MBL between the IL and AL groups was statistically significant (P = 0.003). At 1 year, MBL was 0.086 ± 0.313 mm and 0.005 ± 0.222 mm in the IL and AL groups, respectively. The presence of BoP increased with time in IL, whereas it decreased in AL group (P < 0.001). A minor complication was encounted in one FPD.

CONCLUSIONS

A low grade of MBL was present after 1 year. IL showed greater amount of MBL and soft tissue inflammation indexes than AL. In FPD, AL may be a safer procedure than IL setup in order to preserve a healthy periimplant tissue.

Vertical Bone Augmentation Using Ring Technique with Three Different Materials in the Sheep Mandible Bone

PURPOSE

The purpose of this study was to examine the volumetric alterations and osseointegration properties in the augmented area of the ring technique using different types of bone graft material in sheep mandible bone.

MATERIALS AND METHODS

Three different materials (columnar forms, 7-mm diameter, 3-mm height) were stabilized using dental implants with a turned surface in the mandible bone of Finnish Dorset cross-bred sheep: group A, autogenous bone; group B, bovine bone; group C, biphasic bone substitute. Animals were euthanized after 5 weeks (N = 6). Three-dimensional image data by digital oral scanner were taken at the surgery and sacrifice, and the volume alteration of the material was calculated. The bone samples were fixed in formalin and dehydrated in ethanol. Resin-embedded samples were subjected to non-decalcified ground sectioning, and histologic and histomorphometric analysis (bone and material area alteration, bone-to-implant contact [BIC]) were done.

RESULTS

In three-dimensional (3D) image analysis, group A showed a statistically higher percentage of remaining materials compared with groups B and C. The histologic observation showed no new bone formations around the implants in all groups, especially at the maxillary site of the implant in the augmented area. In histomorphometric analysis, group A showed a statistically higher percentage of bone area (BA) compared with groups B and C; however, in all groups, bone-to-implant contact (BIC) showed low values, and there were no statistical differences between groups.

CONCLUSION

The results of this study suggested that the autogenous bone maintained bone volume around the dental implant using the ring technique, and the impact of surface properties was of some importance; osseointegration with the turned surface in the augmented area showed low BIC values in all groups.

Treatment outcomes and patient-reported quality of life after orthognathic surgery with computer-assisted 2- or 3-dimensional planning: A randomized double-blind active-controlled clinical trial

INTRODUCTION

Thorough treatment planning is essential for a good clinical outcome in orthognathic treatment. The planning is often digital. Both 2-dimensional (2D) and 3-dimensional (3D) software options are available. The aim of this randomized 2-arm parallel double-blinded active-controlled clinical trial was to compare the outcomes of computer-based 2D and 3D planning techniques according to patient-reported health related quality of life. The hypothesis was that a 3D technique would give a better treatment outcome compared with a 2D technique.

METHODS

Orthognathic treatment for 62 subjects, aged 18 to 28 years, with severe Class III malocclusion was planned with both 2D and 3D techniques. After treatment planning but before surgery, the patients were randomly allocated via blind collection of 1 enveloped card for each subject in a 1:1 ratio to the test (3D) or the control (2D) group. Thus, the intervention was according to which planning technique was used. The primary outcome was patient-reported outcome measures. The secondary outcome was relationship between patient-reported outcome measures and cephalometric accuracy. Questionnaires on the patient's health-related quality of life (HRQoL) were distributed preoperatively and 12 months after surgical treatment. The questionnaires were coded, meaning blinding throughout the analysis. Differences between groups were tested with the Fisher permutation test. The HRQoL was also compared with measurements of cephalometric accuracy for the 2 groups.

RESULTS

Three subjects were lost to clinical follow-up, leaving 57 included. Of these, 55 subjects completed the questionnaires, 28 in the 2D and 27 in the 3D groups. No statistically significant difference regarding HRQoL was found between the studied planning techniques: the Oral Health Impact Profile total showed -3.69 (95% confidence interval, -19.68 to 12.30). Consistent results on HRQoL and cephalometric accuracy showed a difference between pretreatment and posttreatment that increased in both groups but to a higher level in the 3D group. A difference between pretreatment and posttreatment HRQoL was shown for both groups, indicating increased quality of life after treatment. This supports recent findings comparing 3D and 2D planning techniques. No serious harm was observed during the study.

CONCLUSIONS

Improvements of HRQoL were shown after treatment independent of which planning technique, 2D or 3D, was used. No statistically significant difference was found between the planning techniques.

REGISTRATION

This trial was not registered.

PROTOCOL

The protocol was not published before trial commencement.

FUNDING

This project was supported by personal grants to Martin Bengtsson from the Scandinavian Association of Oral and Maxillofacial Surgeons (25000 SEK), the Southern Region of the Swedish Dental Association (50000 SEK), and the Swedish Association of Oral and Maxillofacial Surgeons (25000 SEK). The sponsors had no influence on the study design, analysis of the data, or the writing of the article.

Craniofacial height in relation to cross-sectional maxillary and mandibular morphology

BACKGROUND

In order to gain a better understanding of how growth of the alveolar bone is linked to the vertical development of the face, the purpose of this study was to investigate if there is an association between the cross-sectional morphology of the maxillary and mandibular bodies with the craniofacial height, using images from cone beam computed tomography (CBCT).

METHODS

From 450 pre-treatment CBCT scans, 180 were selected to be included in the study. Lateral head images were generated from the CBCT scans and were used to categorise subjects into three groups based on their vertical craniofacial height. Cross-sectional images from CBCT volumes were reformatted of the maxillary and mandibular bodies at five locations in the maxilla and five in the mandible. Each image was measured at one height and two width measurements. Statistical analysis performed was the one-way analysis of variance with a Tukey post hoc test. A significance level of 5% was used in all comparisons.

RESULTS

Patients with large vertical craniofacial height had a significantly higher cross-sectional area both in the maxilla and in the mandible. In the same group, the cross-sectional area was significantly thinner in the mandible compared with the other two groups, especially in the anterior region.

CONCLUSIONS

This study further highlights the close relationship between craniofacial height and alveolar bone dimensions and contributes with important knowledge for planning and follow-up of comprehensive dental- and orthodontic treatments.

Bacterial diversity in medication-related osteonecrosis of the jaw

OBJECTIVE

The aim was to study the association between microflora and medication-related osteonecrosis of the jaw (MRONJ) by using culture-independent molecular techniques to detect bacteria in necrotic bone lesions.

STUDY DESIGN

Included were 18 consecutive patients with MRONJ, 10 with osteoporosis and 8 cancer patients. Bone biopsies were retrieved from the center of the necrotic bone and from visually healthy bone, and 16 S rRNA gene fragments from bacterial DNA were amplified with polymerase chain reaction.

RESULTS

The study revealed a diversity of bacteria represented by 16 S rRNA sequences in all the necrotic bone samples and in 60% of the visually healthy bone. Eight dominating taxa groups were identified at the genus level: Porphyromonas, Lactobacillus, Tannerella, Prevotella, Actinomyces, Treponema, Streptococcus, and Fusobacterium.

CONCLUSIONS

The necrotic bone lesions contained mainly anaerobic bacteria, representative of periodontal microflora, suggesting that a periodontal infection in combination with antiresorptive treatment could initiate osteonecrosis.

Treatment with local hemostatic agents and primary closure after tooth extraction in warfarin treated patients

The aim of this retrospective study was to assess the frequency of postoperative bleeding in patients on warfarin after tooth removal followed by a complete soft tissue closure of the surgical site. A total of 124 consecutive patients, 69 males and 55 females with a mean age of 71 years (range 28-95 years) were included in this study. Inclusion criteria were patients on warfarin with an INR <or=3.5 who were referred for tooth removal (single or multiple) during 2004-2009. After tooth extraction all sockets were packed with an absorbable haemostatic gelatin sponge or a collagen fleece and subsequently the sockets was primary closed with sutures. 5/124 (4%) patients returned with postoperative bleedings. All patients with a postoperative bleeding had received a surgical extraction in the posterior part of the maxilla. Consequently no patient had a postoperative bleeding in the mandible. None of the 124 patients returned to the clinic with a dry socket or postoperative pain. 3/124 (2%) patients returned with postoperative infection that required antibiotic treatment. All patients who bled were managed conservatively and none was admitted to hospital.

CONCLUSION

According to the protocol of this study (local hemostatic, primary closure, sutures and tranexamic acid) the risk of postoperative bleeding after tooth removal in patients on continued warfarin medication is low.

Endosseous implants and bone augmentation in the partially dentate maxilla: an analysis of 17 patients with a follow-up of 29 to 101 months

PURPOSE

The aim of this study was to analyze the survival rate of endosseous implants placed in the partially dentate maxilla treated with sinus inlay block bone grafts.

MATERIALS AND METHODS

Seventeen patients were subjected to bone augmentation procedures prior to or in conjunction with implant placement. Bone volumes were regarded as insufficient for implant treatment unless a bone grafting procedure was performed. The patients were treated with sinus inlay block bone grafts and endosseous implants in a 1- or 2-stage procedure. A total of 69 implants were placed in the patients who were followed for 29 to 101 months (mean, 53.1 months). The retrospective patient group was also prospectively followed using a standardized clinical and radiographic study design.

RESULTS

The implant survival rate was 91.3% (63/69). All implants were lost during the period from abutment connection to connection of the definitive prosthesis. All bone grafts were stable. Bone grafts supported 48 implants, of which 5 failed (10.4%). In the residual bone, 21 implants were placed, of which 1 failed (4.8%). All patients received a fixed partial prosthesis, which was stable during the follow-up period.

CONCLUSION

The results of this investigation revealed a satisfactory clinical outcome of implant placement in grafted partially dentate maxillae after a mean follow-up of 53.1 months.

Evaluation of 31 zygomatic implants and 74 regular dental implants used in 16 patients for prosthetic reconstruction of the atrophic maxilla with cross-arch fixed bridges

BACKGROUND

The use of a specially designed implant to be anchored in the zygomatic body has been proposed as an alternative to bone grafting in the prosthetic rehabilitation of the severely resorbed maxilla. However, few studies have evaluated the long-term stability and soft tissue conditions of zygomatic implants.

PURPOSE

The aim of this retrospective study was to evaluate the clinical performance of zygomatic implants when used for prosthetic reconstruction of atrophic maxillae.

MATERIALS AND METHODS

Sixteen patients consecutively treated with 31 zygomatic implants and 74 additional dental implants from 1998 to 2002 were retrospectively evaluated and prospectively followed using a standardized clinical and radiographic study design. Data were collected from the time of implant treatment until the last follow-up

RESULTS

The follow-up period ranged from 9 to 69 months from the day of implant treatment, with a mean of 46.4 months (3 years, 10 months). Three (9.7%) of the 31 zygomatic implants were surgically removed because of recurrent sinusitis. Three (4.1%) of the 71 additional dental implants failed to integrate. Poor oral hygiene and gingivitis were seen at most zygomatic implant sites (10/16). Local infections were observed in 9 of 16 patients. Sinusitis occurred in 6 patients. All patients (16/16) eventually received fixed bridges, which were stable throughout the observation period.

CONCLUSIONS

The results showed an acceptable outcome with regard to implant and prosthetic survival rates. However, postoperative complications not related to implant and prosthesis stability were frequent. Further investigations of the long-term performance of zygomatic implants and with a focus on soft tissue and maxillary sinus health are needed.

Survival analysis of endosseous implants in grafted and nongrafted edentulous maxillae

PURPOSE

The aim of this study was to analyze and compare the survival rates of endosseous implants placed in the edentulous maxillae of patients in whom bone augmentation was undertaken prior to or in conjunction with implant placement with survival rates in patients who did not undergo bone augmentation.

MATERIALS AND METHODS

This study included 2 retrospective patient groups: the graft group, which included 64 patients with 437 implants, and the nongraft group, which included 118 patients with 683 implants. The patients were treated consecutively between 1990 and 1996. In addition, the retrospective patient groups were also followed prospectively using a standardized clinical and radiographic study design.

RESULTS

The implant survival rate was 75.1% for the graft group and 84.0% for the nongraft group after a mean follow-up of 5 to 6 years, a statistically significant difference. However, there was no difference with regard to the prosthesis survival rate, and after reoperation, more grafted patients had a fixed prosthesis at the end of the study (87.5% versus 85.3%). Implant failure appeared to be related to the original jawbone volume in the anterior regions. In the premolar region, where the inlay graft technique was used, the implant survival rate for the graft group was comparable to that of the nongraft group. The graft group had significantly more failures than the nongraft group in the incisor region, but not in the canine, premolar, or molar regions.

DISCUSSION

The majority of implant failures occurred before loading. Occlusal overload during the healing period may have been a causative factor.

CONCLUSIONS

The overall implant survival rate was lower in grafted maxillae than in nongrafted maxillae after a mean of 5 to 6 years of follow-up. Analysis revealed that jawbone volume in the anterior regions at the start of treatment was directly related to implant survival rates in both groups: the greater the volume, the higher the survival rate. Moreover, the implant survival rate was similar in grafted posterior edentulous maxillae of classes V and VI and in nongrafted posterior edentulous maxillae of classes III and IV.

Transverse displacement of the proximal segment after bilateral sagittal osteotomy

PURPOSE

The aim of the present investigation was to evaluate the transverse displacement of the proximal segment and ramus rotation after a bilateral sagittal osteotomy (BSO) with rigid internal fixation (RIF) using bicortical LAG screws.

PATIENTS AND METHODS

We conducted a retrospective review of 37 patients (14 males and 23 females, age range of 14 to 55 years) who underwent a mandibular advancement with BSO and RIF. Posteroanterior and lateral cephalometric radiographs were obtained 1 to 8 weeks before and 1 to 4 weeks after surgery. The transverse displacement and angulation of the proximal segments after surgery were measured on posteroanterior radiographs, using the best-fit method. The amount of mandibular advancement was compared with the amount of transverse displacement of the proximal segments.

RESULTS

In the 1 to 4-week postoperative period after a BSO, 36 of 37 subjects showed an increased transverse intergonion distance (5.6 mm) (P <.0001) and 35 of 37 patients showed an increased transverse interramus width (3.3 mm) (P <.0001). No correlation was found between mandibular advancement and transverse displacement of the proximal segment.

CONCLUSIONS

The study results indicate that transverse displacements of the proximal segments occur with BSO and RIF. The clinical impact on temporomandibular joint symptomatology or surgical relapse with such displacement was not assessed in the study. Future studies that address these issues may help to determine whether there is an association between proximal segment displacement and surgical relapse, temporomandibular dysfunction, or both.

Craniofacial and dental manifestations of Proteus syndrome: a case report

The Proteus syndrome is a rare congenital hamartomatous condition that is characterized by a wide range of malformations, sometimes involving the face. Common manifestations include partial gigantism, congenital lipomas, and plantar hyperplasia. In this report we describe the craniofacial clinicopathological development in a girl with Proteus syndrome from age 6 to 20 years. The patient had pronounced hemifacial hypertrophy, exostoses in the left parietal region, and enlargement of the inferior alveolar nerve and mandibular canal in the affected region. The dental development of the affected left mandible and maxilla was characterized by extremely premature development and eruption of the primary and permanent teeth and by pronounced idiopathic root resorptions. The multidisciplinary management of the patient and the treatment outcome is reported. A review of the Proteus patients in the literature who exhibited manifestation in the craniofacial region is presented.

The influence of mandibular dentition on implant failures in bone-grafted edentulous maxillae

PURPOSE

To evaluate the influence of mandibular dentition on the performance of maxillary implants prior to definitive prosthesis attachment in maxillae that have been reconstructed with autogenous bone grafts.

MATERIALS AND METHODS

A retrospective review of 90 consecutive patients, 31 men and 59 women, with a mean age of 57.4 years, was conducted. All patients underwent treatment planning to receive endosseous implants in the edentulous maxilla in conjunction with autogenous bone grafting. During the time from implant and/or bone graft placement until placement of the definitive restorations in the maxillae, the mandibular dentitions were recorded and categorized into 6 groups based upon the presence and distribution of teeth.

RESULTS

Of 643 implants placed, 118 (18.4%) were lost between implant placement and definitive prosthesis placement. The type of mandibular dentition was significantly associated with implant failure during this time interval (P < .001). In particular, the patients with implants opposing unilateral occlusal support showed the highest rate of implant failure (43.8%, or 28 of 64 implants). Implants that opposed a mandibular implant-supported fixed prosthesis demonstrated an implant failure rate of 14.3% (10 of 70), and in patients with a removable mandibular denture, the implant failure rate was 6.2% (4 of 65 implants failed). The overall mean patient follow-up was 64.2 months. At 60 months, the cumulative implant failure rate based on the Kaplan-Meier method was 20.2%.

DISCUSSION

Unfavorable concentration of forces on the maxilla may contribute to increased risk of implant failure.

CONCLUSION

Effort should be made to create a favorable occlusion in the mandible, with attention being paid to broad distribution of occlusal contacts.

Growth analysis of a patient with ectodermal dysplasia treated with endosseous implants: a case report

Congenital absence of multiple teeth and poorly developed alveolar ridges are associated with ectodermal dysplasia. Affected patients often require dental prosthetic treatment during their developmental years. Maxillofacial growth and development in a preadolescent female patient with ectodermal dysplasia following oral rehabilitation with maxillary and mandibular endosseous dental implants is reported. Four maxillary and 4 mandibular implants were successfully integrated and restored at 8 years of age. Growth analysis 12 years later revealed that the implants followed maxillary and mandibular growth displacement. Minor impaction of the maxillary implants was observed, and mandibular implants were affected by the mandibular growth rotation, which led to a change in implant inclination. The treatment outcome is compared to similar previously reported studies and cases.

A sella turcica bridge in subjects with severe craniofacial deviations

In earlier studies, a sella turcica bridge was stated to occur in 1.75 to 6 per cent of the population. The occurrence of a sella turcica bridge has not previously been studied in a group of patients with craniofacial deviations treated by surgery. Profile radiographs from 177 individuals who had undergone combined orthodontic and surgical treatment at the Copenhagen School of Dentistry were studied. A sella turcica bridge was registered in those subjects where the radiograph revealed a continuous band of bony tissue from the anterior cranial fossa to the posterior cranial fossa across the sella turcica. Two types of sella turcica bridge were identified. A sella turcica bridge occurred in 18.6 per cent of the subjects.