In Vitro Investigation into the Effect of Cryopreservation on the Mechanical Characteristics of Dental Hard Tissues.

Previous research has reported on hidden damage within the dentin introduced by cryopreservation, but the effect on the mechanical properties of the hard tissues at tooth level remains unclear. The main objective of this study is to investigate the effect of cryopreservation on the mechanical properties of teeth. A matched sample of 234 premolars of 117 children (9 ≤ age ≤ 16 years), bilaterally extracted for orthodontic reasons, were included. For each child, one tooth was randomly allocated to the cryopreservation group and the contralateral tooth was assigned to the control group. Static compression tests were performed to determine load to failure, stiffness, and toughness. In a subgroup of 20 teeth, a cyclic preloading or chewing simulation was performed. Additionally, the fracture mode was determined, and the microstructure of the fractured surfaces was examined using a scanning electron microscope (SEM). Linear mixed model analyses could not detect a statistical difference in the mean load to failure (p = 0.549), mean toughness (p = 0.968), or mean stiffness (p = 0.150) between cryopreserved and non-cryopreserved teeth. No significant difference in load to failure after cyclic preloading was detected between groups (p = 0.734). SEM analysis revealed comparable fracture characteristics between groups. It is concluded that cryopreservation does not affect the mean load to failure, stiffness, or toughness of teeth, indicating that hidden damage in the dentin is not critical at tooth level.

Reliability of the novel cleft lip and palate smile esthetic index (CLP-SEI).

BACKGROUND/OBJECTIVES: The aim of this research was to determine the reliability of a novel index for the assessment of smile esthetics in patients with cleft lip and/or palate (CL ± P) at the end of their multidisciplinary treatment, for use in clinical and academic settings. MATERIALS AND METHODS: Five orthodontists, five periodontologists, five general practitioners, five dental students, and five laypeople rated the smiles of 10 patients with CL ± P twice at a 2 weeks interval. The rating scale consisted of four main categories: 1. nasolabial esthetics, 2. gingival esthetics, 3. dental esthetics, and 4. overall esthetics. A total of 15 parameters were rated. Intra- and inter-rater agreements were calculated using SPSS. RESULTS: The inter-rater agreement varied between good and excellent whereby the orthodontists, periodontists, general practitioners, dental students, and laypeople obtained agreement scores of 0.86, 0.92, 0.84, 0.90, and 0.89, respectively. The intra-rater agreement was good with agreement scores of 0.78, 0.84, 0.84, 0.80, and 0.79, respectively. LIMITATIONS: Smile esthetics were rated on static pictures, not in real life or by video recordings in a young adult population. CONCLUSIONS/IMPLICATIONS: The cleft lip and palate smile esthetic index is a reliable tool for the assessment of smile esthetics in patients with CL ± P.

Rapid maxillary expansion vs slow maxillary expansion in patients with cleft lip and/or palate: a systematic review and meta-analysis.

OBJECTIVES: To compare the dentoalveolar outcomes of slow maxillary expansion (SME) and rapid maxillary expansion (RME) used for maxillary expansion before secondary alveolar bone grafting in patients with cleft lip and/or palate (CL/P). Secondarily, the advantages and disadvantages of SME vs RME were reviewed. MATERIALS AND METHODS: A systematic search was conducted up to November 2021, including Medline (via PubMed), Embase (via Ovid), Web of Science, Cochrane Central, and Google Scholar. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. Risk-of-bias assessment was performed using the Risk of Bias (RoB 2.0) and Risk Of Bias In Non-randomized Studies of Interventions (ROBINS I) tool. Overall quality was assessed using the Grading of Recommendations Assessment, Development, and Evaluation tool. RESULTS: Of 4007 records, five studies met the inclusion criteria. The randomized control trial (RCT) had a low risk of bias, the non-RCTs presented with a moderate risk of bias. Arch width and perimeter increased significantly with both SME and RME treatments. No difference in the increase in palatal depth was found. The meta-analysis showed a greater anterior-to-posterior expansion ratio for the Quad Helix (QH) appliance. The results for dental tipping were not conclusive. CONCLUSIONS: SME and RME promote equal posterior expansion in cleft patients. The anterior differential expansion is greater with SME (QH appliance). No clear evidence exists concerning the amount of dental adverse effects of SME and RME in cleft patients.

A non-cephalometric three-dimensional appraisal of soft tissue changes by functional appliances in orthodontics: a systematic review and meta-analysis.

BACKGROUND: Patients with dental and skeletal Class II growth patterns present typical facial characteristics. Functional appliance (FA) therapy is one of the conventional orthodontic treatment modalities used to harmonize these facial imbalances. OBJECTIVES: The aim of this systematic review was to investigate and summarize the effects of FAs on the facial soft tissues captured in three dimensions. SEARCH METHODS: A systematic search was conducted up to December 2020. Databases Medline (via PubMed), Embase (via Ovid), Web of Science, and Cochrane Central were searched without language restrictions. SELECTION CRITERIA: Randomized clinical trial (RCT)'s investigating the influence of FA therapy on the facial soft tissues in a non-cephalometric and three-dimensional (3D) manner, were included. DATA COLLECTION AND ANALYSIS: Data extraction was independently undertaken by two authors. In case of conflict, a third author was consulted. RoB 2.0 tool was used to assess the risk of bias. A meta-analysis was performed for total facial height, upper lip length, lower lip length, commissural width, and facial depth. The single-step activation versus incremental approach was compared using a random effects model. RESULTS: Five studies were included in the qualitative synthesis of the systematic review. Facial height increased after FA therapy. Three studies met the criteria for the meta-analysis. The mean facial depth increased significantly (P < 0.003) with 1.39 mm (0.46 to 2.32). CONCLUSIONS: Current evidence suggests a positive influence of the FA therapy on the soft tissues in Class II patients. However, conclusions were drawn based on a two-dimensional analysis of 3D images, suggesting that more controlled studies using a comprehensive 3D analysis are necessary to confirm these results. REGISTRATION: PROSPERO registration (CRD 42021224016).

A non-cephalometric two-dimensional appraisal of soft tissue changes by functional therapy in Class II patients: a systematic review and meta-analysis.

BACKGROUND: Facial attractiveness has social, psychological, and economic repercussions. Class II malocclusions are associated with a retroposition of the mandible, facial convexity, protruded upper lip, retruded lower lip, and pronounced mentolabial fold. Functional appliances (FA) try to increase mandibular length and normalize lip position, thereby decreasing the facial profile convexity and aesthetics. OBJECTIVES: The aim of this review and meta-analysis is to investigate the effects of FA on the soft tissues in a non-cephalometric two-dimensional manner. SEARCH METHODS: Medline (via PubMed), Embase (via Ovid), Web of Science, and Cochrane Central were used to identify studies describing the soft tissue results of FA in a non-cephalometric way. The search was conducted up to July 2021. SELECTION CRITERIA: Prospective and retrospective studies investigating the effects of FA appliances on the soft tissues, with non-ionizing, two-dimensional imaging, including an attractiveness assessment based on Visual Analogue Scale or Likert scale, were considered eligible. DATA COLLECTION AND ANALYSIS: Data extraction was performed separately by two authors. Risk of bias was assessed using the ROBINS-I tool. RESULTS: From the eight eligible studies, four were included in the meta-analysis to investigate the influence of assessors on facial attractiveness scores. Age range of the included studies varied from 8 to 21 years old including 313 Caucasian patients whereof 64% females. Six out of eight studies used growing patients as treatment group and only two studies reported follow-up after the end of treatment. Overall facial attractiveness increased after treatment with FA, resulting from a decrease in facial convexity and a normalization of the lip relationship. Orthodontists score higher aesthetic improvements after FA treatment as compared to laypeople. CONCLUSIONS: Current evidence suggests the positive effects of FA on the facial attractiveness in growing and non-growing patients. FA normalize the lip relationship. Furthermore, they tend to decrease facial convexity and advance the chin point. More pleasing results can be expected in growing patients. Orthodontists are more generous when assessing treatment changes as compared to laypeople. REGISTRATION: PROSPERO registration (CRD42021254835).

The orthodontic bonding properties of human enamel after cryopreservation.

The aim was to investigate the effect of cryopreservation on the enamel bonding properties of orthodontic brackets. Sixty-six human premolars were randomly allocated to a control group or a cryopreserved group. Conventional stainless-steel orthodontic brackets were bonded with a light cure adhesive on the buccal side of the premolars. The shear bond strength (SBS) was determined at a crosshead speed of 1 mm/min. The SBS and adhesive remnant index (ARI) were evaluated respectively by an independent samples t test and Fisher's exact test (α≤0.05). The mean failure load was lower in the cryopreserved group. However, this difference in SBS was not significant (p=0.443). In both groups, the ARI mostly indicated a failure at the enamel-adhesive interface. The mean ARI scores for both groups were not significantly different (p=0.099). Within the limitations of this macro bond strength testing, it can be concluded that cryopreservation does not significantly affect the bonding properties of enamel.

The Effect of Autologous Alveolar Bone Grafting on Nasolabial Asymmetry in Unilateral Cleft Lip and Palate.

The objective of this study was to examine whether an autologous alveolar bone graft has an effect on the nasolabial asymmetry in unilateral cleft lip, alveolus, and palate. Fifteen children (mean age 7.5 ±â€Š2.4 years) with non-syndromic unilateral cleft lip and palate (CLP) were included. Non-ionizing three-dimensional images were acquired prior to and three months after the alveolar bone grafting procedure. A 2D and a landmark-independent 3D asymmetry assessment were used to detect changes of asymmetry in the nasolabial area. For the 2D assessment, a cleft and non-cleft side ratio for 4 linear nasal and 2 linear labial distances was expressed as a Coefficient of Asymmetry (CA). The 3D asymmetry assessment comprised a robust superimposition of the face with its mirror image, expressed as a root-mean-square-error (RSME) in mm. A significant decrease in the CA for the labial distance from the facial midline to the labial commissure was observed (P = 0.036). Also, the CA for the labial distance from the facial midline to the highest point of Cupid's bow increased significantly (P = 0.028). Non-significant changes were observed for the CA for the 2 nasal distances and the 2 other labial distances. No significant changes in 3D nasal asymmetry were detected (P = 0.820). Alveolar bone grafting completes the alveolar ridge but has only little to no clinical effect on the asymmetry of the secondary cleft lip nasal deformity.

The in vitro remineralizing effect of CPP-ACP and CPP-ACPF after 6 and 12 weeks on initial caries lesion.

OBJECTIVE: The aim of this in vitro study was to determine the effects of remineralization promoting agents containing casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP), or CPP-ACP in combination with fluoride (CPP-ACPF) on artificial white spot lesions (WSLs) after 6 and 12 weeks. METHODOLOGY: White spot lesions were created on 123 sectioned premolars (246 specimens) with a demineralization solution during a 96 hours pH-cycling regime. Two experimental groups were created: a CPP-ACP group (Tooth Mousse™), and a CPP-ACPF group (Mi Paste Plus™). Additionally, two control groups were created, one using only a conventional toothpaste (1450 ppm fluoride) and another one without any working agents. All teeth were also daily brushed with the conventional toothpaste except the second control group. Tooth Mousse™ and Mi Paste Plus™ were applied for 180 seconds every day. The volume of demineralization was measured with transverse microradiography. Six lesion characteristics regarding the lesion depth and mineral content of WSLs were also determined. RESULTS: The application of CPP-ACP and CPP-ACPF had a significant regenerative effect on the WSLs. Compared to Control group 1 and 2 the volume of demineralization after 6 weeks decreased significantly for CPP-ACP (respectively p<0.001 and p<0.001) and CPP-ACPF (respectively p=0.001 and p=0.003). The same trend was observed after 12 weeks. For the CPP-ACPF group, WSL dimensions decreased significantly between 6 and 12 weeks follow-up (p=0.012). The lesion depth reduced significantly after application of CPP-ACP and CPP-ACPF but increased significantly in the Control groups. Mineral content increased for CPP-ACP and CPP-ACPF after an application period of 12 weeks, but this was only significant for CPP-ACP. CONCLUSIONS: Long-term use of CPP-ACP and CPP-ACPF in combination with a conventional tooth paste shows beneficial effects in the recovery of in vitro subsurface caries lesions.

A retrospective intercenter comparison of two surgical protocols through the dental arch relationship of 5- to 6-year-old unilateral cleft patients.

OBJECTIVES: The objectives of this retrospective equivalence trial were to assess the dental arch relationship of 5- to 6-year-old patients with unilateral cleft lip and palate (UCLP) treated in two specialized cleft centers with a different surgical protocol using the 5-Year-Olds' Index and the modified Huddart/Bodenham scoring system, and to determine the correlation between these two scoring indices. MATERIALS AND METHODS: The dental arch relationship of seventy-three 5- to 6-year-old patients with complete UCLP was evaluated on plaster casts using the 5-Year-Olds' Index and the modified Huddart/Bodenham scoring system. The sagittal occlusion, overbite, and overjet were also recorded. Inter- and intra-examiner agreement was determined using Intraclass Correlation Coefficients. RESULTS: A good to very good inter- and intra-examiner agreement was found. No significant mean difference in outcome based on the 5-Year-Olds' Index, the modified Huddart/Bodenham scoring system, overjet, or overbite was detected. For mean difference in sagittal occlusion, the hypothesis that both centers are clinically equivalent was confirmed. A strong negative correlation (rs = - 0.832) between the 5-Year-Olds' Index and the modified Huddart/Bodenham scoring system was found. CONCLUSIONS: The dental arch relationship of 5- to 6-year-old unilateral cleft patients treated in two Belgian cleft centers is clinically equivalent based on sagittal occlusion, despite substantial differences in their treatment protocol. Clinical equivalence for other parameters was not confirmed. There is a strong correlation between the 5-Year-Olds' Index and the modified Huddart/Bodenham scoring system. CLINICAL RELEVANCE: A well-implemented treatment protocol for cleft patients is of the utmost importance, but case load and skill of the surgeon are also important factors for the quality of the results.

The in vitro remineralizing effect of CPP-ACP and CPP-ACPF after 6 and 12 weeks on initial caries lesion

Abstract Objective: The aim of this in vitro study was to determine the effects of remineralization promoting agents containing casein phosphopeptide-stabilized amorphous calcium phosphate (CPP-ACP), or CPP-ACP in combination with fluoride (CPP-ACPF) on artificial white spot lesions (WSLs) after 6 and 12 weeks. Methodology: White spot lesions were created on 123 sectioned premolars (246 specimens) with a demineralization solution during a 96 hours pH-cycling regime. Two experimental groups were created: a CPP-ACP group (Tooth Mousse™), and a CPP-ACPF group (Mi Paste Plus™). Additionally, two control groups were created, one using only a conventional toothpaste (1450 ppm fluoride) and another one without any working agents. All teeth were also daily brushed with the conventional toothpaste except the second control group. Tooth Mousse™ and Mi Paste Plus™ were applied for 180 seconds every day. The volume of demineralization was measured with transverse microradiography. Six lesion characteristics regarding the lesion depth and mineral content of WSLs were also determined. Results: The application of CPP-ACP and CPP-ACPF had a significant regenerative effect on the WSLs. Compared to Control group 1 and 2 the volume of demineralization after 6 weeks decreased significantly for CPP-ACP (respectively p<0.001 and p<0.001) and CPP-ACPF (respectively p=0.001 and p=0.003). The same trend was observed after 12 weeks. For the CPP-ACPF group, WSL dimensions decreased significantly between 6 and 12 weeks follow-up (p=0.012). The lesion depth reduced significantly after application of CPP-ACP and CPP-ACPF but increased significantly in the Control groups. Mineral content increased for CPP-ACP and CPP-ACPF after an application period of 12 weeks, but this was only significant for CPP-ACP. Conclusions: Long-term use of CPP-ACP and CPP-ACPF in combination with a conventional tooth paste shows beneficial effects in the recovery of in vitro subsurface caries lesions.

The evaluation of the transport medium for extracted premolars prior to cryopreservation: an in vitro study.

Autotransplantation is a versatile technique for the replacement of a missing tooth and cryopreservation can expand its scope. The aim of this in vitro study is to compare the antimicrobial effect of different transport protocols on procured teeth prior to cryopreservation. Streptococcus oralis biofilms were grown on ten sterile premolars, incubated for 48 h and subjected to the following transport procedures: an untreated (contaminated) control group, a group rinsed with phosphate buffered saline (PBS), a group transported in PBS, a group transported in Dulbecco's Modified Eagle's medium (DMEM) supplemented with fetal calf serum (FCS), and a group transported in DMEM supplemented with FCS and antibiotics (AB). The effect of cryopreservation as such, as well as the combination with a transport medium (DMEM + FCS + AB) on the contamination was also tested. The surviving bacteria were harvested, and determined by plate counting. There was no significant reduction in contamination after rinsing the tooth, after transport in PBS or after transport in DMEM with FCS. Significant reductions were observed for transport in DMEM with AB when compared to the control group (p = 0.003). Cryopreservation as such reduced the biofilm significantly (p < 0.001). No cumulative effect could be found when transport in DMEM + FCS + AB was followed by cryopreservation. Within the limitations of this laboratory set-up, DMEM + FCS + AB was the most effective transport medium in S. oralis biofilm elimination. It could not be concluded that rinsing of the tooth gives an additional reduction. Cryopreservation as such decontaminated the teeth more effectively than any tested transport procedure.

The evaluation of the transport medium for extracted premolars prior to cryopreservation: a systematic literature review.

Prior to cryopreservation, a tooth is transported from a contaminated oral environment to the tooth bank. Our objective was to identify all studies reporting or investigating a transport protocol prior to the cryopreservation of teeth, in terms of decontamination of the subjects. The systematic literature search (1970-2017) was based on MEDLINE via PubMed, Web of Science and the Cochrane Library. The reference lists of the included studies and the Science Citation Index were used for hand searching (snowballing). Only studies reporting the transport conditions of the transplant were included. Language restrictions for English, Dutch or French were applied. The search led to 14 eligible studies. Almost all studies were laboratory studies, so the methodological quality of evidence was low. The majority of the included studies was performed by only five different research groups and the number of subjects varied between 1 and 120 teeth. In general, the teeth were stored in a tissue culture medium supplemented with fetal calf serum and/or different combinations of antibiotics and/or antimycotics. The teeth were transported cooled (4 °C) or at room temperature, for a period of time not exceeding 24 h. Only three studies reported the irrigation of the teeth with phosphate buffered saline prior to the transport. The optimisation of the decontamination during transport was investigated in three studies (from 1971, 1980 and 1982). It was concluded that the literature on this topic is scarce, and the decontamination protocol for teeth, prior to cryopreservation has not been validated recently.

An esthetic evaluation of unilateral canine substitution for a missing maxillary lateral incisor.

OBJECTIVES: The aim of this study is to determine whether variation in size, morphology, and color of a unilateral substituted maxillary canine has influence on the dentogingival attractiveness perceived by dental professionals and laypeople. MATERIALS AND METHODS: A frontal clinical photograph of a patient with unilateral canine substitution was used as standard picture. Five different series were created by modification of following parameters with a raster graphics editor (Photoshop CS 6): (1) width, (2) color, (3) gingival margin height, and (4) crown tip morphology of the substituted canine and (5) the gingival margin height of the neighboring first premolar. For each parameter, the photograph deviating the most from the standard photograph, was combined into a final series. Four groups of examiners (orthodontists, periodontists, dentists, and laypeople) were asked to rank the photographs from most to least attractive. RESULTS: One hundred seventy-four examiners ranked the photographs in order of attractiveness. Overall, a darker canine color (mean rank 4.36 ± 1.03) and a more pronounced canine tip morphology (mean rank 3.47 ± 1.11) were significantly ranked as most unattractive (P < .05). The gingival height of the neighboring premolar was ranked as least unattractive by all groups of examiners (mean rank 1.30 ± 0.74). CONCLUSIONS: Darker canine color and a pronounced tip morphology of a substituted canine are rated as the most unattractive by dental professionals and laypeople. CLINICAL SIGNIFICANCE: The present study showed that the canine color and crown tip morphology are important parameters when considering unilateral canine substitution, both for professionals and laypeople. There is a general preference in favor of canines with a light color and a reduced incisal tip.

An experimental study on periodontal regeneration after subcutaneous transplantation of rat molar with and without cryopreservation: an in vivo study.

This study analysed the effects of cryopreservation on periodontal regeneration of autotransplanted rat molars. First and second maxillary molars (n=92) of 24 four-week-old Wistar rats were gently extracted and autotransplanted into the abdominal tissue immediately (control group n=44) or after cryopreservation in liquid nitrogen for 7 days (experimental group n=48). At 1, 2, 4 and 10 weeks after transplantation, the transplanted molars were excised and regeneration of the periodontal tissues was analysed on histological sections stained with routine H&E and Goldner method. Different tissue responses were scored on a tooth basis: inflammation, regeneration of the periodontal ligament, resorption/apposition of cementum, and alveolar bone formation. Sixty-two teeth were available for histological evaluation, including 30 experimental and 32 control samples. One week after transplantation, both control and test teeth were surrounded by granulation tissue and some areas of root resorption could be seen. After 2 weeks, signs of regeneration of the periodontal ligament, cementum apposition, and new bone formation roughly coincided in both groups, however markedly retarded in the experimental group. After 4 weeks, regeneration progressed equally in both groups, presenting fewer areas of cementum apposition in experimental samples. Finally, 10 weeks after baseline transplantation, no significant differences between both groups could be observed. Cryopreservation followed by autotransplantation of extracted teeth in rats appears to have minimal detrimental effects on regeneration of periodontal tissues after integration periods of 1-10 weeks. However, the present findings indicated that the regeneration process in general is retarded for cryopreserved teeth, as compared to their immediately transplanted homologues.

Influence of cryopreservation on the pulpal tissue of immature third molars in vitro.

The purpose of this study was to evaluate in vitro the viability of isolated and non-isolated pulpal tissue of immature third molars after cryopreservation. This study was divided in three different experiments. Experiment 1: Pulpal tissue isolated from 19 third molars was divided in horizontal segments. Each segment was cultured separately in order to evaluate whether differences in growth capacity within the tissue could be found. Experiment 2: Pulpal tissue isolated from 27 third molars was divided in a mesial and a distal part. One part was cryopreserved before culturing, the other part was cultured immediately. Growth capacity of cryopreserved and non-cryopreserved tissue was evaluated and compared. Experiment 3: 43 third molars were cryopreserved. After thawing, the dimension of the apical foramen was measured and the pulp was isolated and segmented horizontally. The different parts were cultured and growth capacity was evaluated and compared. Results of experiment 1 and 2 showed no significant difference in growth capacity between fibroblasts originating from different pulpal segments of the same tooth without cryopreservation and between fibroblasts originating from cryopreserved and non-cryopreserved isolated pulpal tissue. In experiment 3 it was demonstrated that the dimension of the apical foramen and pulpal viability after cryopreservation are positively correlated. A minimum dimension of 9.42 mm(2) enables the cryoprotective agent to penetrate sufficiently and to protect the pulpal tissue from apex to crown. This study proved that cryopreservation of human pulpal tissue is possible if the cryoprotective agent can reach the entire pulp.

Influence of cryopreservation on human periodontal ligament cells in vitro.

Cryopreservation of teeth before autotransplantation may create new possibilities in dentistry. The purpose of this study was to examine the effect of a standardised cryopreservation procedure on human periodontal ligament (PDL) cell cultures. Human PDL fibroblasts obtained from immature third molars of 11 patients were cultured and divided into two groups. The experimental group was cryopreserved and cultured after thawing. The control group was cultured without cryopreservation. A comparison was made between cryopreserved and control cells. To evaluate possible differences in the characteristics of the fibroblasts, the cells in both groups were tested for viability (membrane integrity), growth capacity and alkaline phosphatase (ALP) expression. The Wilcoxon test for paired comparison between cryopreserved and non-cryopreserved cells was performed for each characteristic. The results showed that membrane integrity of cells was not influenced by cryopreservation. There was no statistically significant difference in growth capacity between cryopreserved and control cells. Non-cryopreserved cells were slightly stronger positive for ALP, but the difference was not statistically significant. From these experiments it can be concluded that the observed parameters are not influenced by cryopreservation.

Tooth transplantation and cryopreservation: state of the art.

Autotransplantation of teeth is useful and has many indications in dentistry. Cryopreservation of teeth creates new possibilities--eg, when autotransplantation is needed, but the recipient site is too small and orthodontic treatment is needed to gain space for the transplant. This review article examines the reactions of various dental tissues after autotransplantation vs after autotransplantation with cryopreservation. Various subjects will be discussed, including periodontal healing, pulp reactions, and root development after autotransplantation with and without cryopreservation.