Displacement of dental implants in trabecular bone under a static lateral load in fresh bovine bone

AIM

The study aims to provide objective data for the displacement of titanium screw implants in trabecular bone specimens. One hundred Semados implants (Bego, Bremen, Germany) were inserted in bovine type IV bone specimens. All implants had a diameter of 3.75 mm; 50 implants had a length of 8.5 mm and 50 implants had a length of 15 mm. Insertion torque was determined at intervals of 10, 20, and 30 Ncm. Implants were loaded horizontally with 10, 20, and 30 N for 2 seconds. An indicator strip was attached to the implant abutment to allow direct observation of implant movement relative to the bone surface. Horizontal displacement was assessed with an accuracy of measurement of 10 µm. Seven implants got lost by visible loosening. Degree of displacement was subject to evaluation with all others. Those implants showed a mean displacement of 59 µm for 10 N (n = 100), 173 µm for 20 N (n = 99), and 211 µm for 30 N (n = 93). The mean displacement of 15-mm implants (16, 37, 51 µm) was significantly lower compared with 8.5-mm implants (103, 311, 396 µm) corresponding to 10, 20, and 30 N as lateral loads.

CONCLUSIONS

Displacement of screw implants in trabecular bone can be detected and visualized using commercially available endoscopes with a high magnification. A lateral load of 20 N indicates a mean displacement of over 100 µm and therefore results in a critical displacement.

Tongue position after deglutition in subjects with habitual open-mouth posture under different functional conditions

OBJECTIVE

To test the null hypothesis of no significant differences in (1) the duration of the post-deglutory, cranial tongue rest position (CTP) between different functional orofacial conditions and (2) the presence or absence of an oral screen (OS) in subjects with a habitual open-mouth posture.

SUBJECTS

Twenty-nine subjects (aged 6-16; mean: 9.69 years; 13/16 girls/boys) were selected according to the inclusion criterion of a habitual, daytime open-mouth posture.

METHODS

Deglutition was screened at baseline during resting respiration using orofacial polysensography and simultaneous assessment of tongue-to-palate position and nasal airstream, during five functional intervals of 8 min each: F1 without instruction (RR); F2 the same, but including an oral screen (RROS); F3 with OS and the instruction to maintain a tongue-to-palate contact (IROS); F4 with OS and the instruction to perform tongue repositioning manoeuvres at the time of spontaneous swallowing (TRMOS); and F5 corresponds to F3 omitting OS (IR). Duration and frequency of deglutition were analysed descriptively as well as by anova and subsequent multiple comparisons, and the CTP was evaluated with chi-square tests and paired comparisons at a significance level of 5%.

RESULTS

Of 542 identified swallowing acts, 75% were accompanied by a post-deglutory CTP. Mean duration of CTP increased for functional conditions RR/1.01s > RROS/2.56s > IR/3.21s > IROS/6.53s > TRMOS/6.58s. The null hypothesis (1) was rejected in comparison of resting respiration (F1, F2) with IROS and TRMOS, whereas the use of an oral screen alone did not significantly prolong the duration of CTP.

Intra-oral compartment pressures: a biofunctional model and experimental measurements under different conditions of posture

Oral posture is considered to have a major influence on the development and reoccurrence of malocclusion. A biofunctional model was tested with the null hypotheses that (1) there are no significant differences between pressures during different oral functions and (2) between pressure measurements in different oral compartments in order to substantiate various postural conditions at rest by intra-oral pressure dynamics. Atmospheric pressure monitoring was simultaneously carried out with a digital manometer in the vestibular inter-occlusal space (IOS) and at the palatal vault (sub-palatal space, SPS). Twenty subjects with normal occlusion were evaluated during the open-mouth condition (OC), gently closed lips (semi-open compartment condition, SC), with closed compartments after the generation of a negative pressure (CCN) and swallowing (SW). Pressure curve characteristics were compared between the different measurement phases (OC, SC, CCN, SW) as well as between the two compartments (IOS, SPS) using analysis of variance and Wilcoxon matched-pairs tests adopting a significance level of α = 0.05. Both null hypotheses were rejected. Average pressures (IOS, SPS) in the experimental phases were 0.0, -0.08 (OC); -0.16, -1.0 (SC); -48.79, -81.86 (CCN); and -29.25, -62.51 (SW) mbar. CCN plateau and peak characteristics significantly differed between the two compartments SPS and IOS. These results indicate the formation of two different intra-oral functional anatomical compartments which provide a deeper understanding of orofacial biofunctions and explain previous observations of negative intra-oral pressures at rest.

Functional treatment of snoring based on the tongue-repositioning manoeuvre

Orofacial biofunction comprises muscular and physical effects, which may contribute to stabilization of the oropharyngeal airway. The tongue-repositioning manoeuvre (TRM) provides physical stabilization of the tongue and the soft palate together with, as a prerequisite, a nasal breathing mode. The aim of the present study was to evaluate the influence of a TRM treatment concept on primary snoring. The TRM was used to achieve a closed biofunctional rest position of the orofacial system and to re-educate the nasal breathing pattern. Pressure indicating oral shields were used for home exercises as a biofeedback instrument and to support nocturnal mouth closure. Treatment was undertaken on 125 consecutive primary snorers [101 males, mean age 52.4 years, range 34-75, mean body mass index (BMI) 28.1, range 18.9-38.5, and 24 females, mean age 55.2 years, range 36-70, mean BMI 26.8, range 22.7-31.9]. Bed partner ranking was performed, and snoring was judged using a 10-cm visual analogue scale (VAS). The VAS score was 8.4 (range 6-10) before treatment and decreased to 4.1 (range 0-10) after treatment [mean observation time 4.6 months (1-10)]. Analysis of variance showed a significant influence of treatment in subjects with a normal body weight (BMI 18.5-25). The data provide evidence that dynamic stabilization of the orofacial system with the TRM in conjunction with nocturnal wear of an oral shield is beneficial for reducing the symptoms in primary snorers with a normal BMI.

On the interaction between incisor crown-root morphology and third-order angulation

OBJECTIVE

To evaluate the significance of crown-root angles (CRAs) by testing the null hypothesis that there are no significant differences in deviations of third-order angles to axial inclination values between Angle Class II division 2 incisors and a neutral occlusion control sample.

MATERIALS AND METHODS

The study group comprised n(total) = 130 whites with either Angle Class II division 2 (n(1) = 62; group A) or neutral (n(2) = 68; control group B) occlusal relationships. Upper central incisor inclination (U1) was assessed with reference to the cephalometric lines NA and palatal plane (U1NA/deg, U1PP/deg). Craniofacial sagittal and vertical relations were classified using angles SNA, SNB, ANB, and NSL-PP. Third-order angles were derived from corresponding dental cast pairs using an incisor inclination gauge. Welch's two-sample t-tests (alpha-level: .05) were used to test the null hypothesis. Single linear regression was applied to determine third-order angle values as a function of axial inclination values (U1NA, U1PP) or sagittal craniofacial structures (ANB angle), separately for group A and B.

RESULTS

The discrepancy between axial inclination (U1NA, U1PP) and third-order angles is significantly different (P < .001) between groups A and B. Regression analysis revealed a simply moderate correlation between third-order measurements and axial inclinations or sagittal craniofacial structures.

CONCLUSION

The hypothesis is rejected. The results of this study warn against the use of identical third-order angles irrespective of diminished CRAs typical for Angle Class II division 2 subjects. Routine CRA assessment may be considered in orthodontic treatment planning of Angle Class II division 2 cases.

Flapless implant surgery: an experimental study

OBJECTIVE

The purpose of this study was to examine the effect of flapless implant surgery on crestal bone loss and osseointegration in a canine mandible model.

STUDY DESIGN

In 6 mongrel dogs, bilateral, edentulated, flat alveolar ridges were created in the mandible. After 3 months of healing, 2 implants in each side were placed by either flap or flapless procedures. After a healing period of 8 weeks, microcomputerized tomography at the implantation site was performed. Osseointegration was calculated as percentage of implant surface in contact with bone. Additionally, bone height was measured in the peri-implant bone.

RESULTS

The mean osseointegration was greater at flapless sites (70.4%) than at sites with flaps (59.5%) (P < .05). The mean peri-implant bone height was greater at flapless sites (10.1 mm) than at sites with flaps (9.0 mm) (P < .05).

CONCLUSION

Flapless surgery can achieve results superior to surgery with reflected flaps. The specific improvements of this technique include enhanced osseointegration of dental implants and increased bone height.

Flapless sinus floor augmentation using endoscopy combined with CT scan-designed surgical templates: method and report of 6 consecutive cases

PURPOSE

Sinus floor augmentation has become a routine procedure with predictable results. Flapless implant placement is recommended for a series of indications with sufficient bone volume. Flapless surgery in the atrophic maxilla is presented as a refinement of the endoscopic subantroscopic laterobasal sinus floor augmentation (SALSA) technique.

MATERIALS AND METHODS

Based on computerized tomography (CT) scans, the site of sinus trephination and implant positions are planned using a commercially available planning program, and surgical templates are fabricated according to the data of the treatment plan. Subantral space is augmented using the SALSA technique without raising a mucoperiosteal flap. Implants are placed transgingivally without raising a mucoperiosteal flap, with endoscopic control of the cover screw at the bone level.

RESULTS

In a case series of 6 patients, 21 implants were placed and augmented simultaneously. The mean augmentation height was 10.7 mm (range, 5.7 to 16.6 mm); the mean residual bone height was 5.1 mm (range, 1.9 to 12.1 mm). Complications such as insufficient primary stability and sinus membrane perforation were treated without changing to an open surgical approach.

DISCUSSION AND CONCLUSION

Flapless sinus augmentation (FSA) can reduce the surgical trauma significantly. The procedure has high acceptance by the patient and less postoperative discomfort. FSA enlarges the spectrum of minimally invasive surgery and may offer better vascularization and less alveolar resorption.

Immediate Occlusal Loading of Freestanding Implants Using Cortical Satellite Implants: Preliminary Report of a Prospective Study

Freestanding implants with mandibular overdentures are used frequently after 3 months' healing time. Immediate full loading may be applied to this approach if sufficient primary stability is provided. The present study evaluates the success rate of two single-standing interforaminal implants stabilized with cortical satellite implants and loaded immediately with overdentures. Twenty patients (five male and 15 female; age, 45-87 years) received two single-standing titanium screw implants (Semados, Bego, Bremen, Germany). All implants were stabilized during healing time with cortical satellite implants (2.0-mm bone screws; Medartis, Basel, Switzerland) via individual connectors attached to the implant abutment subgingivally. Mandibular overdentures were incorporated immediately after surgery using ball attachments as retentive elements. The patients were under no restrictions concerning diet and loading. The satellite implants were removed after 3 months. All implants were osseointegrated after 10 months' mean observation time. The mean Periotest value was -4.9, and the mean marginal bone loss was 0.7 mm. No dropouts were observed, and 19 of 20 patients would recommend the treatment to a close friend. Preliminary follow-up data indicate that cortical stabilization of two anterior mandibular implants with satellite implants leads to osseointegration of the implants under immediate load conditions with an overdenture. This concept contributes to reduction of prosthetic treatment costs and permits immediate enhancement of masticatory function.

Autotransplantation of immature third molars into edentulous and atrophied jaw sections

The aim of the present study was to assess the results after transplantation of 85 immature third molars. Recipient site conditions varied and different surgical techniques were used. The long-term results after preparation of a new alveolus, splitting osteotomy of the alveolar process or use of free bone autografts were compared with the results after transplantation into a fresh extraction site (control group). Transplantations into prepared sockets showed equal results to the control group (94% respectively). Transplantations in connection with free bone autografts (84%) or after splitting osteotomy of the alveolar process (63%) showed poorer success rates, the differences between the latter and the control group being statistically significant. A possible correlation to revascularization disturbances of the pulp due to an insufficiency of the recipient site or to postoperative infection is suspected. The results show that transplantation of immature third molars is a safe, useful procedure when appropriate conditions of the recipient site are present. Where the alveolus is atrophic, a splitting osteotomy should be performed only in exceptional cases and preference should be given to alternative methods such as primary bone augmentation or bone-regenerative procedures.

In Vitro Evaluation of Horizontal Implant Micromovement in Bone Specimen With Contact Endoscopy

Primary stability of dental implants is mandatory for their osseointegration. A method is described that allows objective measurements of implant displacement in bone sites during lateral loading. Ten samples of bovine bone (2 cm x 2 cm) with bone type II, III, and IV according to Lekholm and Zarb were used for the experiment. Ten Semados dental implants of 15-mm length and 3.75-mm diameter were placed. All implants were loaded with lateral forces of 5, 10, 20, and 30 N through 8-mm abutments for 2 seconds each. Lateral displacement was observed by means of contact endoscopy. Micromovement was detected with the help of a transmitter strip attached to the abutment. Endoscopic images were processed digitally and microdisplacement was calculated relative to the reference body (microscrew) placed adjacent to the implant. Micromovement observed varied with the force applied. Lateral force of 5 N resulted in a mean displacement of 39 microm; for 30 N, the mean displacement was 157 microm. Bone type also influenced the amount of movement. Contact endoscopy represents a new method for direct observation of implant movement relative to the bone surface in vitro. In combination with support immersion technique, contact endoscopy could be used as an office procedure to evaluate intraoperatively implant stability during functional loading.

Subantroscopic laterobasal sinus floor augmentation (SALSA): an up-to-5-year clinical study

PURPOSE

The aim of the article was to introduce a new subantroscopic laterobasal sinus augmentation (SALSA) tecnique as a minimally invasive approach to maxillary peri-implant surgery.

MATERIALS AND METHODS

The SALSA technique consists of the following steps: (1) microsurgical opening of the subantral space (SAS) with detachment of the sinus membrane (SM) under supported videoendoscopy; (2) enlargement of the SAS by laterobasal tunnelling; (3) subantroscopic examination of the SAS with (4) optional reinforcement or repair of the SM; (5) implant site preparation with subantroscopic identification of the cavities; and (6) precise stepwise placement of graft material under endoscopic control.

RESULTS

Since 1996, 118 sinus augmentations have been performed on 83 patients using particulate alloplastic augmentation material (tricalcium phosphate) with various amounts of autogenous bone and blood. Mean augmentation height was 8.6 mm (range, 1 to 15 mm). Twenty-eight perforations of sinus mucosa were observed without further complication (1 case of sinusitis was treated and re-augmented endoscopically). Of 211 titanium screw-type implants placed, 11 failures were observed.

DISCUSSION

SALSA is a predictable surgical technique. With this minimally invasive method, adequate bone height can be achieved.

CONCLUSION

SALSA may offer advantages related to lower morbidity, conservation of bone volume and blood supply, optimized view of the surgical field, and high acceptance by patients.

Real-time endoarticular ultrasound imaging of the TMJ--a new diagnostic possibility? A cadaver study

Recent advances in ultrasound imaging suggested endoarticular ultrasound imaging of the temporomandibular joint (TMJ) in combination with TMJ-arthroscopy as a new diagnostic method. Our investigations were performed on human cadavers, in combination with traditional TMJ-arthroscopy. During our investigations, the main articular structures were identified: the glenoid fossa of the temporal bone, articular disc, condyle of the mandible, and retrodiscal tissue. The combination of arthroscopy and ultrasound imaging provides more information on position, movement, and pathological changes in joint structures. Although all of the advantages, disadvantages, indications, and complications of this new diagnostic procedure are not yet clear, the authors consider this new method a useful diagnostic procedure for TMJ imaging.

[Evaluation of B-scan ultrasound, 3-D ultrasound, roentgen diagnosis and sinus endoscopy in follow-up assessment of the maxillary sinus after sinus floor elevation]

PROBLEM

The aim of this study was to determine which technique--B-scan sonography, 3D sonography, X-ray, or endoscopy--is the most effective for diagnosis in changes of the maxillary sinus after sinus lift and simultaneous augmentation.

MATERIAL AND METHODS

In 33 patients the maxillary sinus was examined before sinus lift, 1 week and 6 months postoperatively with a 7.5-MHz linear scanner and 3D sonography. At the same time, the sonographic results were compared with the X-ray as well as the endoscopic results. Endoscopy of the maxillary sinus was only applied during the sinus lift operation and the abutment operation after 6 months.

RESULTS

A total of 56 operations of sinus lift and simultaneous augmentation with autogenous bone were carried out. Preoperatively, there where no pathological findings detectable in the maxillary sinus. One week postoperatively, the X-rays as well as the sonographic images revealed thickening of the mucosa in 40 maxillary sinuses. After the healing period of 6 months, polyposa was still detected in three cases sonographically, in the radiographic follow-up as well as endoscopically. The sonographic 3D imaging of the maxillary sinus improved the spatial visualization of postoperative changes in the maxillary sinus and the reliability of the diagnosis.

CONCLUSION

Due to the lack of radiation, the cost effectiveness, and its reproducibility, sonography is suitable as a primary screening technique in recall. In cases of normal sonographic findings but clinical symptoms, CT, MRT, and endoscopy should be performed to exclude pathological processes of the posterior maxillary sinus.

Enhancement of primary stability of dental implants using cortical satellite implants

PURPOSE

This study aims to assess the effect of satellite implants on the primary stability of dental implants placed in fresh extraction sites in vitro.

METHOD

34 titanium screw implants (3.75 mm x 10 mm; Bego, Bremen, Germany) were inserted in premolar- and molar-fresh extraction sites in domestic pig mandibles. Periotest (PT) values were assessed before and after insertion of one vestibular and one lingual 1.7-mm bone screw (Mondeal, Tuttlingen, Germany) as a satellite implant was connected to the implants with a 0.6-mm microplate welded to the implant abutment.

RESULTS

The average PT values were 2.9 without satellite implants, -1.0 with one satellite implant, and -2.5 with two satellite implants during horizontal testing, and 3.0, 1.4, and 0.4, respectively, for vertical testing.

CONCLUSION

Satellite implants increase the horizontal stability of implants in fresh extraction sites. Differences for horizontal PT assessment were significant on a 0.01 level of confidence. Implants in extraction sites may be loaded immediately, if vertical stabilization is provided by cortical bone and if horizontal PT values show sufficient stability after satellite implant insertion.

Endoscopic and ultrasonographic evaluation of the maxillary sinus after combined sinus floor augmentation and implant insertion

OBJECTIVE

The aim of our study was a radiographic, endoscopic, and ultrasound follow-up of the maxillary sinus comparing 2 techniques of sinus floor augmentation.

STUDY DESIGN

Sonograms, radiographs (Waters' view) of the sinuses, and endoscopy served before and during surgery to evaluate the maxillary sinus. One week after the operation, ultrasound and radiograph follow-up (Waters' view) were carried out. Six months after the operation, we performed an ultrasound follow-up along with uncovering the implants. If any pathologic condition was found, we took another x-ray film of the sinuses, performed another endoscopic examination, or both.

RESULTS

In 23 of 63 patients, healing was uneventful. Waters' view revealed opacification of the maxillary sinus 1 week after surgery in 40 cases when the "window technique" was used. Sinusitis occurred 3 times, as a result of migration of bone chips in 2 patients. We lost 11 of 132 inserted implants during the healing and loading periods.

CONCLUSION

Endoscope-controlled sinus floor augmentation may lower the complication rate in a remaining height of the jaws between 4 and 8 mm. In our group of patients, we proved by endoscopic examination that migration of cancellous bone sequestra was the reason for sinusitis. In case of infected bone grafts with antral symptoms, sinoscopy allowed debridement and removal of a sequestrum.