Creating an anatomical wax-up in partially edentulous patients by means of a statistical shape model.

PURPOSE: Creating wax-ups of missing teeth for backward planning in implant surgery is a complex and time-consuming process. To facilitate implant-planning procedures, the automatic generation of a virtual wax-up would be useful. In the present study, the reconstruction of missing teeth in partially edentulous patients was performed automatically using newly developed software. The accuracy was investigated in order to test its clinical applicability. MATERIALS AND METHODS: This study presents a new method for creating an automatic virtual wax-up, which could serve as a basic tool in modern implant-planning procedures. First, a statistical shape model (SSM) based on 76 maxillary and mandibular arch scans from dentally healthy individuals was generated. Then, artificially generated tooth gaps were reconstructed. The accuracy of the workflow was evaluated on a separate testing sample of 10 individuals with artificially created tooth gaps given as a median deviation, in millimeters. Scans of three clinical cases with partial edentulism were equally reconstructed using the SSM and compared with the final prosthodontic work. RESULTS: The reconstruction of the artificial tooth gaps could be performed with the following median reconstruction accuracy: gap 21 with 0.15 mm; gap 27 with 0.20 mm; gap 34 with 0.22 mm: gap 36 with 0.22 mm; gaps 12 to 22 with 0.22 mm; gaps 34 to 36 with 0.22 mm. A scenario for an almost edentulous mandible with all teeth missing except teeth 33 and 43 could be reconstructed with a median reconstruction accuracy of 0.37 mm. The median tooth gap deviation of the SSM-based reconstruction in clinical cases differed from the final inserted prosthodontic teeth by 0.49 to 0.86 mm in median. CONCLUSION: A first feasibility of creating virtual wax-ups using an SSM could be shown. Artificially generated tooth gaps could be reconstructed close to the original with the proposed workflow. In the clinical cases, the SSM proposes an anatomical reconstruction, which does not yet consider prosthodontic aspects. To obtain clinical use, contact with antagonist teeth must be considered and more training data must be implemented. However, the presented method offers a fast and viable way for the approximate placement of missing crowns. This could be used in a digital planning workflow when implant position must be determined. (Int J Comput Dent 2022;25(4):349-0; doi: 10.3290/j.ijcd.b2599407).

Force-responsive Zyxin modulation in periodontal ligament cells is regulated by YAP rather than TAZ.

In the context of mechanically induced force transmission, the modification of the actin cytoskeleton through involvement of zyxin is an established concept. However, in cells of the periodontal ligament (PDL), which is physiologically subjected to intermittent mechanical forces, the force-responsive modulation of zyxin and the molecular key players, which orchestrate its cellular regulation, have not yet been elucidated. By employing indirect immunofluorescence and western blotting with different subcellular fractions, we show here in stretch force-exposed human PDL fibroblasts (hPDLFs) that (i) the zyxin protein is modulated, and (ii) its subcellular localization is altered. More importantly, using a pharmacological intervention approach, to inhibit the nuclear presence of the co-transcriptional activator yes-associated protein (YAP), we evidence for the first time that on the molecular level, the cellular abundance of zyxin, among the Thyrotrophic Embryonic Factor (TEF)-binding proteins, is regulated by YAP rather than TAZ. Our findings provide novel insights into the topic how cells of the periodontium and the periodontal ligament in particular respond and may adapt to mechanical forces, and first time identify YAP as the key player of the intracellular regulation of the mechano-sensor and mechano-transducer zyxin in hPDLFs. Moreover, the findings broaden the current knowledge on YAP, since so far, currently only very few YAP-regulated genes have been identified.

On the relationship of YAP and FAK in hMSCs and osteosarcoma cells: Discrimination of FAK modulation by nuclear YAP depletion or YAP silencing.

The HIPPO pathway effector YAP has been shown to be regulated by FAK-signaling. However, the existence of an inverse relationship between YAP and FAK is unknown. Here we demonstrate in hMSCs and in the human osteosarcoma derived cell line Saos that Verteporfin- or RNAi-dependent YAP depletion has opposing influence on FAK. While Verteporfin strikingly reduced cellular FAK protein and phosphorylation, RNAi led to an increase of both molecules and point on a generalizable aspect of the YAP/FAK interrelationship. YAP depletion also caused down-regulation of osteogenic genes in hMSCs, irrespective from the YAP intervention mode. Verteporfin induced topological changes in conjunction with reduced protein levels of ß1 integrin, paxillin, and zyxin of focal adhesions (FAs) in hMSCs, suggesting FAK-decrease-related alterations in FAs, which seems to be a FAK-dependent mechanism. On the cell behavioral level, YAP-FAK-interrelation involves proliferation and senescence, as indicated by proliferation inhibition and increase of ß-Galactosidase-activity in hMSCs. Our findings, derived from this dual strategy of YAP intervention, reveal a YAP-FAK relationship in conjunction with molecular and cell behavioral consequences. Moreover, they deepen the current scientific knowledge on YAP from a different scientific point of view, since this inverse YAP/FAK-relationship seems to be transferrable to other cell types, including cell entities with pathological background.

Predictive values of resonance frequency analysis as a diagnostic tool in palatal implant loss.

OBJECTIVES: To determine the diagnostic value of resonance frequency analysis (RFA) in predicting palatal implant (PI) loss. MATERIALS AND METHODS: RFA values of 32 patients (study center at Mainz and Dresden) were evaluated in a prospective randomized controlled trial addressing clinical performance of two loading concepts on PI (Orthosystem, Straumann, Basel, Switzerland). Group 1: conventional loading after a 12-week healing period vs group 2: immediate loading within one week after insertion. Stability was assessed by RFA after surgical insertion (T1), one week (T2), and 12 weeks (T3) later. RESULTS: All 32 PI were clinically stable after surgical insertion; 14 PI were loaded conventionally and 18 immediately. One implant in group 1 was lost 6 weeks after insertion. One drop-out was registered in group 2. One false positive and three false negative implant stability quotients (ISQ) were observed. ISQ values of clinically stable PI in group 1 were 67.2 (SD ± 9.5) at T1, 62.3 (SD ± 11.7) at T2, and 68.2 (SD ± 5.5) at T3. Group 2 showed 67.1 (SD ± 11.7) at T1, 65.4 (SD ± 10.4) at T2, and 72.3 (SD ± 5.6) at T3. Differences between groups were not statistically significant for starting time (P = .88) and change from T1 to T2: 0.08 but were significant from T1 to T3: P = .04; (regression analysis). CONCLUSIONS: RFA had no sensitivity for prediction of stability. General decrease after primary stability and increase with secondary stability gives support for specificity. Within the limits of the study, only the diagnostic value of RFA identifying stable palatal implants could be confirmed.

Biomechanical strain-induced modulation of proliferation coincides with an ERK1/2-independent nuclear YAP localization.

Biomechanical strain induces activation of the transcriptional co-activator yes-associated protein (YAP) by nuclear re-distribution. Recent findings indicate that the mechanically responsive mitogen-activated protein kinase (MAPK) extracellular signal-regulated kinase (ERK) 1/2 is involved in the amount of nuclear YAP, reflecting its activation. In this context, we conducted experiments to detect how biomechanical strain acts on the subcellular localization of YAP in periodontal cells. To this end, cells were subjected to 2.5% static equiaxial strain for different time periods. Western blot and fluorescence imaging-based analyses revealed a clear modulation of nuclear YAP localization. This modulation fairly coincided with the altered course of the KI-67 protein amount in conjunction with the percentage of KI-67-positive and thus proliferating cells. The inhibition of the ERK1/2 activity via U0126 yielded an unchanged strain-related modulation of nuclear YAP localization, while YAP amount in whole cell extracts of strained cells was decreased. Administration of the YAP-inhibiting drug Verteporfin evoked a clear reduction of KI-67-positive and thus proliferating cells by approximately 65%, irrespective of strain. Our data reveal YAP as a regulator of strain-modulated proliferation which occurs in a MAPK-independent fashion.

Orthodontic strain affects the Hippo-pathway effector YAP concomitant with proliferation in human periodontal ligament fibroblasts.

Objectives: During orthodontic tooth movement (OTM), human periodontal ligament fibroblasts (hPDLFs) sense, and respond to mechanical forces. Since the molecular constituents involved in these processes are not fully elucidated, the objective of the present study was to identify further key molecules of the cellular strain response. Materials and Methods: Primary hPDLFs were strained with a static equiaxial strain of 2.5 per cent for 15 minutes, 1 hour, 6 hours, and 24 hours. Western blot (WB) and indirect immunofluorescence (IIF) analyses were performed to investigate the quantity and activation state of proteins involved in mechanotransduction, namely extracellular signal-regulated kinase (ERK) 1/2 and yes-associated protein (YAP). On the cell behavioural level, proliferation was assessed by the marker of proliferation KI-67. Results: In response to the applied strain, an early decline of phosphorylated and thus activated ERK1/2 was observed, followed by a mild recovery. Furthermore, both WB and IIF analyses revealed a modulation of nuclear YAP localisation. Concomitant with the modulation of YAP, the applied strain evoked an early increase in nuclear KI-67 amount, followed by a continuous decrease. Limitations: Consecutive studies will focus on scrutinising the suggested relationship between YAP and proliferation in response to static strain. Conclusions: Our findings provide evidence of ERK1/2 and YAP being biomechanically responsive molecular players in the context of OTM, among which YAP rather than ERK1/2 seems to be mechanistically interrelated with proliferation. Furthermore, the molecular and cell behavioural strain-induced early modulations may point to an involvement of the investigated molecules in the initial and the following lag phase of OTM.

What is the best position for palatal implants? A CBCT study on bone volume in the growing maxilla.

OBJECTIVE: The objectives of the present study are the following: (a) to investigate limitations (bone height, proximity to nasopalatine nerve and roots) in juvenile patients, (b) to review the recommended site for surgical insertion (level of the maxillary first premolars), and (c) to reassess the rationale behind the manufacturer's age limitation (12 years). PATIENTS AND METHODS: Cone beam CT images of 100 patients aged 10 to 20 years were analyzed. Vertical bone heights were measured in the median plane as well as 3- and 6-mm paramedian along the prospective axis of insertion, at the level of the first premolars (level 0), 3 mm anterior (level 1) and 3 mm posterior (level 2). The Mann-Whitney U test was used to compare bone heights between gender groups. RESULTS: The risk of damage to the nasopalatine nerve is highest in the median region on level 1 (46 %). The risk was lowest in the midsagittal region on level 0 (recommended insertion site; 3 %) and level 2 (0 %), as well as paramedian on levels 0 and 2. The risk of damaging roots was irrelevant for median insertion at all levels; the only critical region was 6-mm paramedian on level 1. CONCLUSIONS: The recommendation of surgical insertion at the level of the maxillary first premolars is still justified, but a slightly more posterior implant position might improve safety. We found no relevant growth-related changes in the vertical bone heights in the median palatal area. Thus, our data do not support the strict 12-year age restriction for palatal implants.

Intermediate rehabilitation with (non)-prep all-ceramic onlays in an adolescent patient with oligodontia--4-year follow-up.

BACKGROUND: Initial rehabilitation in juvenile patients with oligodontia is a major challenge for the dentist. Conventional permanent prosthetic and/or implantological treatment options alongside permanent natural teeth are contraindicated in growing patients, because their skeletal development is still in progress. CASE REPORT: A non-invasive temporary-fixed treatment option for an adolescent patient is presented by the use of adhesively cemented (non-prep) all-ceramic onlays of primary teeth. The outcome of treatment was monitored over a period of 4 years. CONCLUSION: Long-term preservation of persistent primary teeth may be a meaningful alternative to removable dentures in growing patients with oligodontia. Intermediate rehabilitation should cause no more than mild psychological stress for the patient and improve quality of life, especially when extensive orthodontic and/or implantological treatment is planned at the end of the patient's skeletal growth.

An interdisciplinary noninvasive all-ceramic treatment concept for nonsyndromic oligodontia in adolescence.

Oligodontia has a substantial oral functional and psychosocial impact on the quality of life of children. The treatment of oligodontia in adolescence is an interdisciplinary approach which can include extraction of the primary teeth with orthodontic space closure, or prosthodontic rehabilitation. This case report describes a conservative approach for the rehabilitation of a 12-year-old patient with 19 ageneses (excluding third molars) of permanent teeth, infraocclusion of the persisting primary teeth, deep overbite, and reduced mesiodistal dimension of the maxillary incisors with a central diastema. The treatment plan to restore esthetics and function included an initial noninvasive prosthetic rehabilitation for deep bite correction with additive leucite-reinforced glass-ceramic onlays/veneers until definitive orthodontic and implant therapy are reevaluated and determined in adulthood. Esthetics, functional occlusion, and crown-to-root ratio remained stable over a follow-up period of 3 years. No signs of fractures within the all-ceramic restorations or symptoms of a temporomandibular disorder were evident.

Sequence-specific labeling of nucleic acids and proteins with methyltransferases and cofactor analogues.

S-Adenosyl-l-methionine (AdoMet or SAM)-dependent methyltransferases (MTase) catalyze the transfer of the activated methyl group from AdoMet to specific positions in DNA, RNA, proteins and small biomolecules. This natural methylation reaction can be expanded to a wide variety of alkylation reactions using synthetic cofactor analogues. Replacement of the reactive sulfonium center of AdoMet with an aziridine ring leads to cofactors which can be coupled with DNA by various DNA MTases. These aziridine cofactors can be equipped with reporter groups at different positions of the adenine moiety and used for Sequence-specific Methyltransferase-Induced Labeling of DNA (SMILing DNA). As a typical example we give a protocol for biotinylation of pBR322 plasmid DNA at the 5'-ATCGAT-3' sequence with the DNA MTase M.BseCI and the aziridine cofactor 6BAz in one step. Extension of the activated methyl group with unsaturated alkyl groups results in another class of AdoMet analogues which are used for methyltransferase-directed Transfer of Activated Groups (mTAG). Since the extended side chains are activated by the sulfonium center and the unsaturated bond, these cofactors are called double-activated AdoMet analogues. These analogues not only function as cofactors for DNA MTases, like the aziridine cofactors, but also for RNA, protein and small molecule MTases. They are typically used for enzymatic modification of MTase substrates with unique functional groups which are labeled with reporter groups in a second chemical step. This is exemplified in a protocol for fluorescence labeling of histone H3 protein. A small propargyl group is transferred from the cofactor analogue SeAdoYn to the protein by the histone H3 lysine 4 (H3K4) MTase Set7/9 followed by click labeling of the alkynylated histone H3 with TAMRA azide. MTase-mediated labeling with cofactor analogues is an enabling technology for many exciting applications including identification and functional study of MTase substrates as well as DNA genotyping and methylation detection.

Treatment outcome and efficacy of an aligner technique--regarding incisor torque, premolar derotation and molar distalization.

BACKGROUND: The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy. METHODS: We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®. RESULTS: The overall mean efficacy was 59% (SD = 0.2). The mean accuracy for upper incisor torque was 42% (SD = 0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD = 0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD = 0.2). CONCLUSION: Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy.

Forces and moments generated by removable thermoplastic aligners: incisor torque, premolar derotation, and molar distalization.

INTRODUCTION: The exact force systems as well as their progressions generated by removable thermoplastic appliances have not been investigated. Thus, the purposes of this experimental study were to quantify the forces and moments delivered by a single aligner and a series of aligners (Invisalign; Align Technology, Santa Clara, Calif) and to investigate the influence of attachments and power ridges on the force transfer. METHODS: We studied 970 aligners of the Invisalign system (60 series of aligners). The aligners came from 30 consecutive patients, of which 3 tooth movements (incisor torque, premolar derotation, molar distalization) with 20 movements each were analyzed. The 3 movement groups were subdivided so that 10 movements were supported with an attachment and 10 were not. The patients' ClinCheck (Align Technology, Santa Clara, Calif) was planned so that the movements to be investigated were performed in isolation in the respective quadrant. Resin replicas of the patients' intraoral situation before the start of the investigated movement were taken and mounted in a biomechanical measurement system. An aligner was put on the model, the force systems were measured, and the calculated movements were experimentally performed until no further forces or moments were generated. Subsequently, the next aligners were installed, and the measurements were repeated. RESULTS: The initial mean moments were about 7.3 N·mm for maxillary incisor torque and about 1.0 N for distalization. Significant differences in the generated moments were measured in the premolar derotation group, whether they were supported with an attachment (8.8 N·mm) or not (1.2 N·mm). All measurements showed an exponential force change. CONCLUSIONS: Apart from a few maximal initial force systems, the forces and moments generated by aligners of the Invisalign system are within the range of orthodontic forces. The force change is exponential while a patient is wearing removable thermoplastic appliances.

Immediate nonfunctional loading of NobelPerfect implants in the anterior dental arch in private practice--5-year data.

BACKGROUND: The concept of scalloped implants to maintain the natural contour of the alveolar ridge has been a source of controversy for many years. PURPOSE: This study examined the long-term clinical performance of the scalloped NobelPerfect implant in a one-stage procedure (immediate loading in the esthetic zone). MATERIALS AND METHODS: In 20 patients, immediate prosthetic restorations were placed on 31 NobelPerfect implants in a private practice and followed for up to 78 months. Twenty-one implants were placed immediately after extraction, seven implants were placed after osseous consolidation of the extraction sockets, and three implants were placed secondary to extended alveolar ridge augmentation procedures. All implants were provisionalized on the day of implant placement and adjusted to clear all contacts in centric occlusion and during eccentric movements. Outcome variables were success rates, marginal bone levels, and pink esthetic score (PES) assessed per implant. RESULTS: One implant failed after 1.4 months. Five patients with six implants in total were scored in the 5-year follow-up as dropouts. Mean follow-up period of remaining 24 implants was 65 months (range, 55-78 months). Cumulative success rates according to the criteria specified by Smith and Zarb were 96.8%. Marginal bone levels averaged 1.1 mm above the first thread. Mean PES ratings were 10.5 (range, 3-13). CONCLUSIONS: Survival rates, marginal bone levels, and esthetic results suggest proof of principle for the preservation of the interproximal bony lamella with a scalloped implant design in long-term data.

Invisalign® treatment in the anterior region: were the predicted tooth movements achieved?

OBJECTIVE: Based on our previous pilot study, the objective of this extended study was to compare (a) casts to their corresponding digital ClinCheck® models at baseline and (b) the tooth movement achieved at the end of aligner therapy (Invisalign®) to the predicted movement in the anterior region. MATERIALS AND METHODS: Pre- and post-treatment casts as well as initial and final ClinChecks® models of 50 patients (15-63 years of age) were analyzed. All patients were treated with Invisalign® (Align Technology, Santa Clara, CA, USA). Evaluated parameters were: upper/lower anterior arch length and intercanine distance, overjet, overbite, dental midline shift, and the irregularity index according to Little. The comparison achieved/predicted tooth movement was tested for equivalence [adjusted 98.57% confidence interval (- 1.00; + 1.00)]. RESULTS: Before treatment the anterior crowding, according to Little, was on average 5.39 mm (minimum 1.50 mm, maximum 14.50 mm) in the upper dentition and 5.96 mm (minimum 2.00 mm, maximum 11.50 mm) in the lower dentition. After treatment the values were reduced to 1.57 mm (minimum 0 mm, maximum 4.5 mm) in the maxilla and 0.82 mm (minimum 0 mm, maximum 2.50 mm) in the mandible. We found slight deviations between pretreatment casts and initialClinCheck® ranging on average from -0.08 mm (SD ± 0.29) for the overjet and up to -0.28 mm (SD ± 0.46) for the upper anterior arch length. The difference between achieved/predicted tooth movements ranged on average from 0.01 mm (SD ± 0.48) for the lower anterior arch length, up to 0.7 mm (SD ± 0.87) for the overbite. All parameters were significantly equivalent except for the overbite (-1.02; -0.39). CONCLUSION: Performed with aligners (Invisalign®), the resolvement of the partly severe anterior crowding was successfully accomplished. Resolving lower anterior crowding by protrusion of the anterior teeth (i.e., enlargement of the anterior arch length) seems well predictable. The initial ClinCheck® models provided high accuracy compared to the initial casts. The achieved tooth movement was in concordance with the predicted movement for all parameters, except for the overbite.

Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients.

OBJECTIVE: To evaluate the demographic, radiological and therapeutic parameters that influence the overall clinical performance of palatal implants subjected to orthodontic loading. PATIENTS AND METHODS: The data of all patients who had received an orthodontic palatal implant for skeletal anchorage between January 1998 and December 2007 were reviewed retrospectively. The primary endpoint was the implant loss. The following parameters were assessed by univariate (log-rank test) and multivariate (Cox's regression) analysis: (a) age and gender, (b) vertical bone height along the prospective implant axis, (c) surgeon's experience and (d) implant type. RESULTS: Two-hundred and thirty-nine palatal implants were inserted in patients aged between 10 and 65 years. In all, 11/239 (4.6%) implants were lost: nine during the healing phase and two under functional loading. On univariate analysis, "surgeon's experience" was associated with a better implant survival and vice versa (P=0.0005; log-rank test). The significance of "surgeon's experience" was confirmed by Cox's regression analysis (P=0.001; Wald test). All other parameters had no impact on implant loss. CONCLUSIONS: The survival probability of palatal implants is not related to demographic and radiological parameters. Implant losses mainly occurred early in the healing phase of the palatal implant. According to our data, "surgeon's experience" is the cornerstone of palatal implant success.

Preoperative diagnostic for palatal implants: Is CT or CBCT necessary?

OBJECTIVE: To evaluate (a) the diagnostic value of lateral radiographs and (b) whether computed tomography (CT) or cone beam computed tomography (CBCT) is necessary in preoperative diagnostics for orthodontic anchorage implants. PATIENTS AND METHODS: We reviewed all patients who had presented for insertion of a palatal implant between January 2003 and December 2007 at the University Hospital Mainz. On the basis of lateral radiographs, the palatal bone was assessed as follows: (a) sufficient (bone height > 4 mm in the implant axis), (b) ambiguous, or (c) insufficient (bone height < 4 mm in the implant axis). In group A the surgical insertion procedure was performed without further radiological investigation. Group C required other types of anchorage. In cases of an ambiguous bone situation (group B), further diagnostic procedures (CT/CBCT) were performed. RESULTS: During the observation period, 105 patients were screened. Fourteen patients opted for alternative treatment leaving 91 patients for final evaluation. In 89 patients (97.8%), the lateral radiographs showed sufficient bone in the vertical dimension. In all of these cases, the availability of sufficient bone was confirmed intraoperatively. Further investigations were performed in two patients (2.2%) of group B (one CT, one CBCT). Finally, one patient had insufficient bone whereas the second had sufficient bone. CONCLUSIONS: Nearly 98% of the patients included in this study had sufficient bone for palatal implant insertion. Lateral radiographs permit correct and reliable evaluation of the quantity of bone in preoperative diagnosis of palatal implants. Additional imaging (CT or CBCT) is only required in rare cases of borderline dimensions.

Does thread design influence relative bone-to-implant contact rate of palatal implants?

AIM: To determine histologically whether (a) changing the thread design between first- and second-generation palatal implants (Straumann, Basel, Switzerland) influences the bone-to-implant contact (BIC) rate of palatal implants subjected to conventional loading, and (b) whether histological evidence of peri-implantitis appears in this setting. PATIENTS AND METHODS: Patients who had received an orthodontic palatal implant for skeletal anchorage between January 1998 and December 2007 were examined. First-generation palatal implants (Straumann, Basel, Switzerland) 3.3 mm in diameter and 6 mm or 4 mm long were used, as were second-generation implants 4.1 mm in diameter and 4.2 mm long. After completion of active orthodontic treatment, the implants were removed and prepared for histological investigation. This study was designed as a comparative analysis of a series of two cases: 28 explanted first-generation (n = 14) and second-generation (n = 14) palatal implants were analyzed. RESULTS: Bone healing was achieved with all implants. Both types of implants revealed a mean bone-to-implant contact (BIC) rate that was nearly equal: 80.7% (SD 10.7%) for the first-generation and 81% (SD 13.1%) for the second-generation implants. Bone resorption was only observed in 5 palatal implants (3/14 of the first, and 2/14 of the second generation). CONCLUSION: Despite differing thread designs, second-generation palatal implants revealed similar bone-to-implant contact rates as did those of the first generation. Few patients presented bone resorption in the peri-implant bone.

Accuracy of Invisalign® treatments in the anterior tooth region. First results.

AIM: To analyse (a) to what extent the pretreatment model at the beginning of the treatment corresponds to the initial position in the ClinCheck® and (b) to what extent the predicted treatment result corresponds to the actual result of the therapy at the end of the treatment. MATERIAL AND METHODS: Pre- and posttreatment models as well as the initial and final position of the ClinCheck with a total of 35 patients aged between 15 and 59 were measured; all of whom were treated by using the Invisalign® technology (Invisalign®, Align Technology, S.C., Calif., USA). The measurement of the initial and final models was conducted by using an electronic digital calliper rule, i.e. that of ClinCheck® using the measurement tool ToothMeasure® of Invisalign® Software. The following parameters in the anterior region were measured: Overjet, Overbite, dental midline shift. RESULTS: Pretreament models and the initial ClinChecks® revealed slight deviations in the parameters overjet 0.08 mm (standard deviation (SD) 0.3), overbite 0.3 mm (SD 0.4) and dental midline deviation 0.1mm (SD 0.4). The final model and the final ClinCheck® revealed larger deviations: the differences for the Overjet were on average 0.4 mm (SD 0.7), Overbite 0.9 mm (SD 0.9) and dental midline shift 0.4 mm (SD 0.5). CONCLUSIONS: The IT-based transmission of mal-aligned teeth into the ClinCheck® presentation provides sufficiently good accuracy. Tooth corrections in the vertical plane were more difficult to realize. A vertical overcorrection in the final ClinCheck®, a case refinement at the end of the treatment or additional measures (e.g. horizontal beveled attachments or vertical elastics) seems useful to achieve the individually intended therapeutic goal.