Chinese Journal of Dental Research, 01/2014

Casein phosphopeptides-amorphous calcium phosphate (CPP-ACP) is a bioactive agent with a base of milk products, which has been formulated from two parts: casein phosphopeptides (CPP) and amorphous calcium phosphate (ACP). CPP was produced from milk protein casein and has a remarkable ability to stabilize calcium phosphate in solution and to substantially increase the level of calcium phosphate in dental plaque. CPP-ACP buffers the free calcium and phosphate ion activities, thereby helping to maintain a state of supersaturation with respect to tooth enamel, reducing demineralisation and promoting remineralisation. The free calcium and phosphate ions move out of the CPP, enter the enamel rods and reform onto apatite crystals. Laboratory, animal and human studies have shown that CPP-ACP inhibits cariogenic activity. CPP-ACP is useful in the treatment of white spot lesions, hypomineralised enamel, mild fluorosis, tooth sensitivity and erosion, and prevents plaque accumulation around brackets and other orthodontic appliances. CPP-ACP also facilitates a normal post-eruptive maturation process and is ideal for protecting primary teeth at a time when oral care is difficult. CPP-ACP has commercial potential as an additive to foods, soft drinks and chewing gum, as well as additive to toothpastes and mouthwashes to control dental caries. Keywords: CPP-ACP, demineralisation, remineralisation, caries prevention

Objective: To present the results of our current research involving the dynamic implant valve approach (DIVA) in cases with human patients. Methods: The new kind of implant was designed with an internal sealing screw that might serve for drug delivery system and possible endoscopic direct observation via its channel. The DIVA was used in cases when the implant insertion should be combined with the maxillary sinus floor lifting and/or bone augmentation procedure. A total of 63 patients (female n = 31, male n = 32, age range 33-67 years old, mean age 49 years old) were treated with DIVA and 218 new type implants were inserted. Results: Out of 218 inserted implants, 146 implants were inserted in the maxilla with bone level 5 mm, and 72 implants were inserted in the maxilla with bone level > 5 mm. The number of implants per patients varied from one to eight. The failure consisted of seven implants (3.2%) in five patients. No correlation was found between failure cases and the bone density or quality. Follow up (4 to 18 months) showed that in 211 cases (96.8%), the implantation was totally successful both from objective clinical, imaging (cone beam computed tomography) and subjective patients' viewpoints. Conclusion: The new dynamic implant valve approach simplified dental implantation procedure and postoperative treatment. The implant with an inner sealing screw could be considered for use in cases when elevation of the maxillary sinus membrane is needed, as well as in cases when bone augmentation procedures or future treatment might be suspected. Keywords: dental implant, maxillary sinus floor lifting, bone augmentation

Objective: To create an in situ matrix environment conducive to stem cells from host bone marrow to promote bone regeneration. Methods: Three-dimensional porous, mineralised collagen (MC) scaffolds were prepared using a freeze-drying process. The microstructure of scaffolds was observed by field emission scanning electron microscopy. The Bose BioDynamic test system was applied to examine their mechanical properties in wet conditions. The effect of scaffolds loaded with stromal cellderived factor-1α (SDF-1α) on migration of stem cells was assessed using a 24-well transwell system. SDF-1α-loaded scaffolds were implanted in the critical size defect in rats and histological staining was used to evaluate the new bone formation. Results: Mechanical testing showed that the MC scaffold featured an increased Young's modulus compared with the pure collagen (Col) scaffold in wet conditions. In addition, the MC scaffold loaded with SDF-1α chemokine improved bone marrow stromal cells' migration. When implanted in mandibular bone defects with 5 mm diameter, the MC scaffolds containing SDF-1α significantly improved the formation of new bone and blood capillaries within the scaffolds, compared with the SDF-1α-loaded Col scaffolds and the control group. Conclusion: The mineralised collagen scaffolds loaded with SDF-1α, which creates a matrix environment conducive to stem cell migration, can be exploited to improve bone self-repair as an alternative to contemporary cell seeding approaches. Keywords: mineralised collagen, scaffold, stromal cell-derived factor-1, mandibular bone, regeneration

Objectives: To explore the method of manufacturing an implant surgery template with a computer-aided design/computer-aided manufacturing (CAD/CAM) technique and evaluate its precision in clinical cases. Methods: Patients referred to the 2nd Dental Center of Peking University who were partially edentulous, were enrolled and scanned with cone beam computed tomography (CBCT). Diagnostic casts were laser scanned to record the configuration of the patients' dentition and mucosae. CBCT and laser scanning data were subsequently loaded into Simplant software. Implant positions were planned in the software with a computer-aided design technique, and surgical templates were fabricated with a rapid prototyping technique. These templates were used to guide implant placement surgery. Results: The mean value of linear deviation was 1.00 mm (range 0 to 2.16 mm) for implant shoulder and 1.26 mm (range 0.51 to 2.86 mm) for the implant apex. The mean angular deviation was 4.74 degress (0.37 to 10.28 degrees). Deviations were higher in the posterior region than anterior. The tooth-supported template provided higher precision than did the tooth/ mucosa-supported template, but no statistically significant difference was found. Conclusion: Computer-guided implant surgery with the CAD/CAM technique provides dentists with a good platform for preoperative planning, precise implant insertion, and ideal rehabilitation. The protocol of this three-dimensional laser scanning technique can provide precision comparable to that of double-scanning. Keywords: tooth implant, computer-aided design, rapid prototyping, implant surgical template, laser scanning

Objective: To locate the centre of resistance of consolidated units of four and six anterior teeth during retraction. Methods: Twelve three-dimensional (3D) models were designed in SolidWorks of the anterior segment with four and six teeth and their supporting structure. A proper force system was applied in each model to retract the teeth bodily. The exact location of the centre of resistances (CRes) was determined. It was found that the path of CRes change in four-tooth and six-tooth units according to the anterior teeth torque. Results: A posterior shift of the CRes by increasing the inclination of teeth was shown. However, vertical position has a fluctuant behaviour. First it moves apically, then it moves incisally. Furthermore, results suggest that in en masse retraction, translation can be achieved with a smaller amount of moment-to-force ratio than in four-incisor retraction. In other words, for bodily retraction of anterior incisor segments, we should apply force in a more apical position. Conclusion: Different anterior torques between 7 and 35 degrees, cannot affect the CRes position dramatically. The area of CRes shifting is 0.92 mm (anterioposteriorly) x 0.74 mm (superior-inferiorly) in the six-tooth unit in the teeth model and 0.85 mm (anterioposteriorly) x 0.82 mm (superior-inferiorly) in the teeth and bone model. In the four-tooth model, the area of CRes shifting is 0.97 mm (anterioposteriorly) x 0.93 mm (superior-inferiorly) in tooth model and 0.77 mm (anterioposteriorly) x 0.87 mm (superior-inferiorly) in the teeth and bone model. Keywords: 3D finite element analysis, anterior teeth, centre of resistance, anterior teeth retraction, anterior tooth inclination

Objective: To evaluate the short-term efficacy of agents containing KNO3 or casein phosphopeptide- amorphous calcium phosphate (CPP-ACP) in the treatment of dentin hypersensitivity. Methods: UltraEZ, containing KNO3 and MI Paste, containing CPP-ACP were applied in this study. The dentin hypersensitivity of 102 subjects was established by a tactile stimulus with a Yeaple preasure probe, and the degree of hypersensitivity was measured using a visual analogue scale (VAS). The patients were divided into four groups: A, B, C and D, using a random number table. UltraEZ, a placebo of UltraEZ, MI Paste, and a placebo of MI Paste were applied to group A, B, C and D respectively for 2 weeks. Dentin hypersensitivity was measured using VAS before the treatment (baseline), on day 2, 7, and 14 during the treatment, and on day 30 and 60 posttreatment. Results: The efficacy of UltraEZ on dentin hypersensitivity was significantly better than that of the corresponding placebo group on day 7 during the treatment, whereas the efficacy of MI Paste exhibited better than that of the placebo group on day 14 during the treatment. However, there were no differences between the efficacy of the two agents on day 14 during the treatment, day 30 or day 60 posttreatment. Conclusion: Both UltraEZ and MI Paste had a significant effect on dentin hypersensitivity. UltraEZ showed quicker effects than MI Paste, but MI Paste had a greater sustained action after treatment than UltraEZ. Keywords: tooth sensitivity, amorphous calcium phosphate, potassium nitrate, fluoride, desensitising agents

Psoriatic arthritis (PsA) is an inflammatory joint disease associated with psoriasis. PsA is often confused with other diseases such as osteoarthritis and rheumatoid arthritis. PsA involving temporomandibular joints (TMJs) are uncommon: only 19 articles with 43 cases have been documented in the literature. TMJ ankylosis caused by PsA is rare, with only six cases having been reported. The authors present four cases of ankylosis of the TMJ secondary to PsA and review the literature. The findings of this study suggest that more attention should be paid to psoriasis patients with TMJ symptoms and proper treatment should be taken to prevent irreversible TMJ damage. Keywords: psoriatic arthritis, temporomandibular joint, ankylosis, radiographic

"Kissing" molars are impacted permanent molars that have occlusal surfaces contacting each other in a single follicular space, with roots pointing in opposite directions. It is deemed to be appropriate to medically investigate mucopolysaccharidosis (MPS) in patients presenting with kissing molars as kissing molars have been linked with MPS. The case of bilateral occurrence of kissing molars in an 18-year-old woman is described. Pathological analysis of the follicular tissue suggested hyperplastic dental follicles. Therefore, this case report analysed the association of impacted permanent teeth with hyperplastic dental follicles, following the review of seven documented reports describing such association. Keywords: kissing molars, impactions, mucopolysaccharidosis (MPS)